Reduction of Sodium and Fat Levels in Natural and Processed Cheeses: Scientific and Technological Aspects


  • Mark E. Johnson,

    1. Author Johnson is with Center for Dairy Research, Univ. of Wisconsin-Madison, Madison, WI 53706, U.S.A. Author Kapoor is with Kerry Ingredients and Flavours, Beloit, WI 53511, U.S.A. Author McMahon is with Western Dairy Center, Utah State Univ., Logan, UT 87322, U.S.A. Author McCoy is with Dairy Management Inc., 10255 West Higgins Rd, Suite 900, Rosemont, IL 60018, U.S.A. Author Narasimmon is with Dairy Management Inc., 10255 West Higgins Rd, Suite 900, Rosemont, IL 60018, U.S.A. Direct inquiries to author McCoy (E-mail:
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  • Rohit Kapoor,

    1. Author Johnson is with Center for Dairy Research, Univ. of Wisconsin-Madison, Madison, WI 53706, U.S.A. Author Kapoor is with Kerry Ingredients and Flavours, Beloit, WI 53511, U.S.A. Author McMahon is with Western Dairy Center, Utah State Univ., Logan, UT 87322, U.S.A. Author McCoy is with Dairy Management Inc., 10255 West Higgins Rd, Suite 900, Rosemont, IL 60018, U.S.A. Author Narasimmon is with Dairy Management Inc., 10255 West Higgins Rd, Suite 900, Rosemont, IL 60018, U.S.A. Direct inquiries to author McCoy (E-mail:
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  • Donald J. McMahon,

    1. Author Johnson is with Center for Dairy Research, Univ. of Wisconsin-Madison, Madison, WI 53706, U.S.A. Author Kapoor is with Kerry Ingredients and Flavours, Beloit, WI 53511, U.S.A. Author McMahon is with Western Dairy Center, Utah State Univ., Logan, UT 87322, U.S.A. Author McCoy is with Dairy Management Inc., 10255 West Higgins Rd, Suite 900, Rosemont, IL 60018, U.S.A. Author Narasimmon is with Dairy Management Inc., 10255 West Higgins Rd, Suite 900, Rosemont, IL 60018, U.S.A. Direct inquiries to author McCoy (E-mail:
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  • David R. McCoy,

    1. Author Johnson is with Center for Dairy Research, Univ. of Wisconsin-Madison, Madison, WI 53706, U.S.A. Author Kapoor is with Kerry Ingredients and Flavours, Beloit, WI 53511, U.S.A. Author McMahon is with Western Dairy Center, Utah State Univ., Logan, UT 87322, U.S.A. Author McCoy is with Dairy Management Inc., 10255 West Higgins Rd, Suite 900, Rosemont, IL 60018, U.S.A. Author Narasimmon is with Dairy Management Inc., 10255 West Higgins Rd, Suite 900, Rosemont, IL 60018, U.S.A. Direct inquiries to author McCoy (E-mail:
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  • Raj G. Narasimmon

    1. Author Johnson is with Center for Dairy Research, Univ. of Wisconsin-Madison, Madison, WI 53706, U.S.A. Author Kapoor is with Kerry Ingredients and Flavours, Beloit, WI 53511, U.S.A. Author McMahon is with Western Dairy Center, Utah State Univ., Logan, UT 87322, U.S.A. Author McCoy is with Dairy Management Inc., 10255 West Higgins Rd, Suite 900, Rosemont, IL 60018, U.S.A. Author Narasimmon is with Dairy Management Inc., 10255 West Higgins Rd, Suite 900, Rosemont, IL 60018, U.S.A. Direct inquiries to author McCoy (E-mail:
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ABSTRACT:  The various types of cheese are nutrient-dense foods that are good sources of calcium, phosphorus, and protein. They are also important ingredients in many highly consumed foods such as pizza, cheeseburgers, and sauces. However, they are also perceived as being high in fat and sodium. Consumers have indicated that they would like to continue utilizing cheese in their diet but would prefer to have lower-fat and lower-sodium products. Fat and salt are important elements in the flavor, texture, food safety, and overall acceptability of cheese. Alternatives to fat and salt are being investigated but have not been found to be acceptable, especially in those products that meet the FDA's definition of low-fat and/or low-sodium. This review is primarily a report on the current status of research to develop desirable cheeses with low-fat and/or low-sodium, their regulatory and labeling status, consumer acceptability, and challenges for further efforts.


Cheese is a nutrient-dense food that contributes 9% of the protein, 11% of the phosphorus, and 27% of the calcium in the U.S. food supply. Furthermore, some manufacturers are now supplementing their products with more additions including vitamin D, omega-3 fatty acids, antioxidants, prebiotics, and probiotics. The 2005 Dietary Guidelines for America recognizes that people who consume dairy foods have better overall diets, consume more nutrients, and have improved bone health, compared to nondairy consumers. However, cheese is also perceived as being high in fat and sodium. This discourages some, especially older, consumers from including cheese in their diets. This group needs higher protein and calcium consumption in order to reduce muscle and bone loss and cheese would provide those nutrients. Unfortunately, cheese has often been reduced in the meals of children in school systems because of fat and sodium concerns. For those who want cheese options, there are a few reduced-fat products, but there are very few fat-free products that have desirable functionality and flavor. This creates a limit in the choices of high-calcium foods that may be served. If methods are developed to reduce sodium and fat content in cheese, products with high nutritional value would be available to consumers without concerns regarding fat and sodium contents.

The 2005 Dietary Guidelines for America recommend that adults limit consumption of sodium to 2300 mg/d. In November 2007, FDA conducted a public hearing on sodium asking for comments on the reduction of daily values of sodium from 2400 mg/d to 1500 mg/d (Nachay 2008). In addition, dietary guidelines, in the United States and most of the industrialized countries, have recommended a reduction in total dietary fat to 30% of total energy (McDonald 2000).

The objective of this article is to review the scientific and technological aspects of sodium and fat reduction in natural and processed cheeses, highlight progress made so far, and to identify opportunities and challenges ahead.

Sources of Sodium and Fat in Cheese

Natural cheese

There are hundreds of varieties of natural cheese. They vary by the milk used to make the cheese, final composition, culture(s), enzymes, and curing or ripening. In many modern factories, the 1st step in cheese making is to standardize the milk casein-to-fat ratio. The exact ratio will depend on the desired fat content of the final cheese. Standardization is accomplished by a number of methods including centrifugal separation of the milk fat creating skim portion and cream portion, then recombining the portions, or by adding cream or nonfat solids, as appropriate, to incoming milk. This step controls the final fat content of the cheese. It is required to produce lower-fat cheese products since the only source of fat in cheese is that naturally occurring in the cream portion of milk.

Consequently, to make a reduced-fat cheese the cheese maker must increase the ratio of protein-to-fat in the milk. To accomplish this, the cheese maker can remove cream (of about 40% fat) from the milk by centrifugal separation or by adding extra protein to the milk. The source of this protein is condensed skim milk or nonfat dry milk. However, for the manufacture of skim milk or low-fat cheeses, the only option is to remove cream. It is not feasible to add sufficient protein to increase the casein-to-fat ratio in order to produce the desired low-fat cheese composition.

After adjusting the casein-to-fat ratio of the milk, coagulant and starter bacteria are added. The starter bacteria are used to ferment the lactose to lactic acid. The rate and extent of acid development is controlled by the cheese maker to produce the final desired body, texture, and flavor characteristics of the cheese. The coagulant enzyme cleaves part of the kappa-casein from the casein micelle resulting in the gelling of the milk. Secondarily, it starts the hydrolysis of the alpha and beta-caseins, which is the 1st step in the protein hydrolysis sequence that develops many of the characteristic cheese flavors.

One of the final steps in the cheese-making process is the addition of salt. Salt addition is the major source of sodium in natural cheese. If cheddar-type cheese were made without added salt, the sodium content would be about 12 mg/50 g of cheese. This is in comparison to the typical sodium content of 310 mg sodium/50 g. In dry salted cheeses like cheddar, the salt is added directly to the curds just before hooping and pressing. In other types of cheese, the salt is added by submersing the cheese in brine for an appropriate period of time. Finally, some cheeses have salt rubbed on the outer side of the cheese. No matter when or how the salt is added to the cheese, it is used for at least 6 purposes in the manufacture and aging of good-quality cheese. They are: (1) encourage syneresis and control final moisture of the cheese, (2) control the metabolism and survival of the starter bacteria, (3) influence the types of secondary organisms that may grow and create flavors during the ripening period, (4) control enzyme activity in the final cheese, (5) control texture of the final cheese as the sodium replaces calcium in the cheese microstructure, and (6) be a component of the expected taste of the cheese. These aspects of salt in cheese have been recently reviewed by Guinee and Fox (2004) and Guinee and O'Kennedy (2007) among others.

In addition, salt plays an important role in the food safety of cheese, especially processed cheese. Bishop and Smukowski (2006) reviewed the literature on food safety of cheeses, especially as related to the storage and distribution temperature of the product. cheddar-type cheeses may be cured or ripened at up to 15 °C for a period of several months and Swiss-type cheeses are cured at 22 to 23 °C. They recommended that pasteurized milk cheeses with < 50% moisture, produced under good manufacturing procedures, with traditional levels of salt, starter culture, pH, and fat be allowed to be distributed at a temperature not exceeding 30 °C. Salt, in addition to pH, Aw, and lactic acid content, is one of the hurdles inherent in maintaining the food safety of these traditional cheeses. Low-fat cheeses have a higher moisture content resulting in a lower salt-in-moisture (S/M) ratio at the same absolute salt content. The amount of salt in the moisture phase of the cheese controls the growth of microorganisms, not the total amount of salt in the food. Lowering the S/M hurdle is a safety and shelf-life concern especially in the distribution and serving of cheeses.

Processed cheese

Processed cheese, in the most generic terms, is a blend of one or more natural cheeses of different ages, emulsifying salts, water, and other dairy and nondairy ingredients. The mixture undergoes heating and continuous agitation to produce a pasteurized product that is homogeneous and has an extended shelf life (Meyer 1973; Thomas 1973; Kapoor and Metzger 2008). The U.S. Code of Federal Regulations (CFR) legally defines processed cheese as belonging to 3 major categories based on the requirements for maximum moisture content, minimum fat content, and the amount and number of allowed optional ingredients (21CFR 133.169 to 133.180) (FDA 2008a). The 3 categories are pasteurized processed cheese (PC), pasteurized processed cheese food (PCF), and pasteurized processed cheese spread (PCS). Pasteurized cheese products are also available that do not have a standard of identity.

The microstructure of processed cheese can be described as a stable oil-in-water emulsion that is supported by a gel network of hydrated and emulsified casein proteins (Palmer and Sly 1943; Shimp 1985; Kapoor and Metzger 2008). During the manufacturing of processed cheese, the addition of emulsifying salts, such as sodium salts of phosphates and citrates, improves the emulsification properties of caseins in natural cheese by disrupting the calcium–phosphate protein network (Gupta and others 1984; Caric and others 1985; Berger and others 1998). The disruption of the natural cheese casein-protein network results in the exposure of hydrophilic and hydrophobic sections of the individual caseins. Subsequently, when shear and heat are applied, the disrupted caseins become hydrated due to hydrophilic interactions with the aqueous phase, which also allow them to interact with the fat phase via hydrophobic interactions (Marchesseau and Cuq 1995; Ennis and others 1998; Lee and others 2003). Emulsifying salts and other ingredients used while formulating a processed cheese, in combination with the processing conditions (cook temperature, cook time, rate of agitation during cooking, and the rate of cooling after manufacture), are the key factors that provide the final processed cheese with its unique microstructure (Kapoor and Metzger 2008). This unique microstructure renders processed cheese with a variety of functional properties (unmelted and melted texture) that can be controlled in specific ways to achieve a variety of end-use functionalities. Moreover, processed cheese is sold in numerous forms such as blocks, slices (slice-on-slice and individually wrapped slices), shreds, and sauces/dips in the United States (Sørensen 2001).

Current U.S. Regulations on Sodium and Fat

According to the U.S. FDA (2008b,c), to make label claims of “reduced sodium” or “reduced-fat,” most foods need to have at least a 25% reduction of sodium or fat levels, respectively, when compared to its conventional counterpart. For a cheese like cheddar, this would mean a reduction in sodium from 310 mg per 50 g to 232 mg per 50 g. For reduced-fat cheddar cheese, it would mean a reduction of fat from 16.6 g per 50 g to 12.5 g per 50 g. Product meeting these definitions have been introduced to the market with some reasonable sales.

For a food to be called “low-fat,” it is required to have a maximum of 3 g fat per reference amount, provided the reference amount is not less than 50 g. Products that have a reference amount of less than 50 g, such as cheese, must meet the fat requirement of 3 g fat in 50 g (FDA 2008e). For a cheese like cheddar, this implies about an 82% fat reduction in total fat. If cheese could be labeled as “low-fat” when it contained 3 g fat per reference amount, it would only require a 68% reduction. This would still be significant but more accurately reflect consumer fat intake. To be labeled as low-sodium, the product cannot contain more than 140 mg sodium per 50 g (FDA 2008d), which would be the equivalent of 0.7% salt. In this review, fat and sodium contents are often reported as “amount per 50 g” to simplify comparison with the regulatory standards. The fat and salt contents of some common cheeses are shown in Table 1 for comparison purposes.

Table 1—.  Sodium and fat content of selected common cheeses.
CheeseServing size (g)Sodium contentaFat contenta
%watermg Na/servingmg Na/50 g% reduction to meet 50-gram rule% salt inmoistureg fat/50 g% reduction to meet 50-gram rule
  1. aData from USDA or by calculation from USDA data.

  2. bLabel information from manufacturer.

Process cheese food (PCF)28.3543359633787.412.676
Process cheese spread (PCS)28.3548381672797.110.672
Processed cheese (PC)28.3539422744819.615.681
Blue cheese28.3542395697808.314.479
Camembert cheese28.0070320571764.112.175
Cheddar cheese28.3537176310554.316.682
Feta cheese28.3555316557755.110.672
Mozzarella cheese, whole milk, freshb28.3560 80141 11.210.070
Mozzarella cheese, low moisture, part skim28.3546150265472.911.273
Mozzarella cheese, whole milk28.3550178314553.214.379
Provolone cheese28.3541248437685.413.377
Swiss cheese28.3537 54 95 01.314.079

Typical sodium contents of processed cheeses (PC, PCF, and PCS) range from 325 to 798 mg/50 g cheese (USDA 2008). Gupta and others (1984) analyzed approximately 21 commercial processed cheese samples for total sodium content. They found that the sodium content of processed cheese ranged from 590 to 815 mg/50 g for PC, 440 to 732 mg/50 g for PCF, and 595 to 770 mg/50 g for PCS, respectively. A study performed by the Center for Science in the Public Interest showed that the sodium content of selected commercial samples of processed cheese ranged from 370 to 785 mg/50 g (Cheese Market News 2005). Therefore, a reduced-sodium processed cheese will have approximately a maximum of 244 to 600 mg/50 g of sodium and a low-sodium processed cheese will have ≤ 140 mg/50 g of sodium (FDA 2008d).

The minimum allowed fat contents in PC, PCF, and PCS according to the CFR are 30%, 23%, and 20%, respectively (FDA 2008a). Therefore, the maximum fat content for a reduced-fat PC will be 22.5%. Similarly, the maximum fat content for reduced-fat PCF will be 17.25% and for reduced-fat PCS will be 15% (FDA 2008e). According to the CFR, a low-fat processed cheese and a fat-free processed cheese (regardless of the type) will need to have a maximum fat content of 6% and 1%, respectively.

The FDA standard 21 CFR 130.10 allows for the production of nutritionally modified versions of standardized foods when making a nutrient content claim. This standard permits the addition of “safe and suitable ingredients to improve texture, add flavor, prevent syneresis, extend shelf life, improve appearance, or add sweetness so that the product is not inferior in performance characteristics to the standardized food defined in 21 CFR 131 through 169.” Since cheeses fall in section 133, this standard is applicable for the production of nutritionally modified versions of standardized cheeses. The use of enzyme-modified cheese to modify flavor is common in the processed cheese industry, but it is not typically used in the natural cheese industry. 21CFR130.10 may allow for the use of modified dairy products to improve the flavor and/or functionality of low-fat natural cheeses. It could also allow the use of fat mimetics, starches, emulsifiers, or other ingredients to improve texture, mouthfeel, or melt in low-fat cheese products.

Manufacture of Lower-Fat Natural Cheese

When interpreting the literature on low-fat or reduced-fat cheese, it is important to note the fat and moisture levels in the cheeses being described as well as the manufacturing procedure used. For the purpose of this review, the U.S. standard will be followed meaning that “low-fat cheese” refers to a cheese containing no more than 6% fat, and “reduced-fat cheese” refers to a cheese with a 25% fat reduction from its full-fat counterpart. The term “lower-fat” will be used as a general term to describe a reduction of fat content without designating a specific fat level in the cheese.

Challenges in manufacturing natural lower-fat cheese

Removing all or a part of the fat from cheese can adversely affect its taste and texture and its functionality (Banks and others 1989; Drake and Swanson 1995; McMahon and others 1996; Banks 2004). Many lower-fat cheeses tend to have a flat and noncharacteristic taste, more translucency, poorer melting and baking properties, and more rubbery and gummy texture and mouthfeel. Lower-fat cheeses also show less change in viscoelastic properties during aging, especially a lack of change in viscous behavior (Ustunol and others 1995). Drake and Swanson (1995) concluded that the manufacture of acceptable cheeses with a fat reduction of up to 33% and good taste and texture is commercially feasible and could be achieved without the need for fat substitutes.

Drake (2008) evaluated the consumer acceptance of lower-fat cheeses through focus groups. The study involved 3 focus groups with full-fat cheese consumers (nonusers) and 3 focus groups with lower-fat cheese consumers (users). Both users and nonusers identified various negatives in lower-fat cheeses such as lacking in flavor, rubbery, sticky, lower meltability, and perceived as not natural and nonappealing compared to full-fat cheeses. All the focus groups identified flavor, texture, and price as the 3 most important attributes when selecting a cheese. The study also found that the users, in spite of regularly consuming reduced-fat cheeses, were still skeptical about selecting lower-fat cheeses.

Childs and Drake (unpublished data) found that consumer acceptance of cheddar and mozzarella drops dramatically when fat content was reduced by more than 50% with the biggest challenge being flavor and texture of the cheeses. Sensory characteristics of low-fat cheese must be improved and comparable to those of full-fat cheese to gain widespread consumer acceptance (Mistry 2001; Ryhanen and others 2001). While the industry has made significant strides in improving the quality of lower-fat cheeses, consumers still do not accept the trade-off in quality versus low-fat content.

Consumer acceptability

There was an increase in market share for lower-fat cheese in the 1990s during their initial stage as consumers became aware of potential health benefits of low-fat cheese, but demand diminished as consumer dissatisfaction with these products developed (Banks 2004). The market for lower-fat cheese at that time was largest in the United States and relatively small in Europe except for the United Kingdom (Hilliam 1996) where sales of low-fat and reduced-fat cheeses grew at a faster rate than the mainstream full-fat cheese market but only represented 8% of total cheese consumption (Guinee and others 1998). Observations of the current retail market suggest this is similar today with the largest number of lower-fat products being in the 25% reduced-fat category, with only a few 50% and 75% reduced-fat cheeses in the retail market (Figure 1; IRI data, as of Dec. 4, 2008). Currently, 15% of adult Americans restrict their consumption of cheese (Narasimmon 2008), and 29% of these “restrictors” would resume normal cheese consumption if the product's taste, texture, and flavor were comparable to the full-fat product. There has been has been a slow increase in the number of new products developed for the low-fat market, however (Figure 2; Mintel data, Jan 5, 2009) to meet this demand.

Figure 1—.

IRI data, as of December 4, 2008.

Figure 2—.

Mintel data, January 5, 2009.

A satisfactory lower-fat mozzarella cheese (containing 10% fat) was developed by Tunick and others (1995) for the U.S. school lunch program with only minor manufacturing variations (lower cook temperature and longer storage). Low-fat and nonfat cheeses are being made for the industrial market but typically only where its use is to provide a cheese component in which texture is not an issue and when flavor can be supplemented in other ways, such as in cheese powders and crackers.


In general, lower-fat cheeses are perceived to be waxier, fracturable, chewy, hard and springy, and less sticky and cohesive, less meltable, and less smooth than full-fat cheese (Bhaskaracharya and Shah 2001; Gwartney and others 2002). This can be readily understood when cheese is considered as a material that consists of a hydrated protein matrix with interspersed fat particles. The greater the amount of fat in relation to protein, the more interruptions there are in the protein matrix and increased interference of long-range interactions between the proteins. Likewise, an absence of fat allows protein interactions to be very extensive resulting in a rubbery texture. Texture of cheese changes during storage, with parameters such as firmness, fracture stress, and strain decreasing with age, but these changes (along with changes related to melting) occur more slowly in lower-fat cheese than they do in full-fat cheese (Guinee and others 2000).

Flavor Another problem or issue with low-fat cheese is lack of characteristic flavor. While the aqueous phase of cheese has been shown to carry the cheese flavor (Barbano 2004), there is a contribution to flavor from fat-derived flavor compounds that produce fatty, diacetyl/buttery, rancid, and lactone flavor notes. Flavor notes of cheddar cheese (such buttery, creamy, caramel) decrease as fat content of cheese is lowered (Fenelon and others 2000). Fat is also responsible for richness and mouthfeel of cheese, and low-fat cheese lacks sensory attributes (Drake and Swanson 1995) and needs some modifications in its making procedure to improve them.

Flavor development in cheese results from a combination of microbial and biochemical activities that lead to the formation of a heterogeneous mixture of volatile and nonvolatile flavor compounds (Fox and Wallace 1997). Alteration of the balance in fat, protein, moisture, and salt in the production of low-fat cheese will result in deficiencies not only in milk fat-derived flavor compounds but also in compounds generated from the interaction of degradation products of lipolysis and proteolysis. The rate of development of uncharacteristic flavors increases with decreases in fat content of cheese (Fenelon and others 2000). Sensory perception of aroma and flavor compounds will also be dependent on the rate of release of flavor compounds during mastication. This will be influenced by the fat content of the cheese and the texture of the cheese (Delahunty and others 1996). Low-fat cheese may develop a brothy flavor defect after long ripening, which has been described as meaty-brothy or burnt-brothy by Milo and Reineccius (1997), who proposed that this is caused by low-fat cheese containing higher amounts of 4-hydroxy-2,5-dimethyl-3(2H)-furanone (furaneol), homofuraneol, and methional.

Melting Low-fat cheese lacks melting and stretching characteristics as fat contributes to pliability and helps in flowability as well. Low-fat mozzarella does not melt or fuse together well during baking, and this only becomes worse when nonfat cheeses are made. They also brown and scorch excessively when such cheese is heated using hot air convection (such as in many modern pizza ovens), which is hardly appetizing for pizza lovers. This occurs because low-fat cheeses dehydrate quickly, losing water from the surface of the shredded cheese, and forming a dry layer that reduces melting and promotes browning or burning. Applying an oil coating to the cheese prior to baking can reduce excessive surface dehydration and subsequent scorching of the cheese (Rudan and Barbano 1997, 1998; Zaikos and others 1999).

Color Appearance and color of the cheese is also important in consumer acceptability. As fat is removed from cheese, the number of light-scattering centers is reduced and low-fat cheeses become less opaque. This becomes apparent especially when the fat level is reduced more than 50%, and is apparent in both cheddar and mozzarella cheeses. As well as the loss of fat, other changes to composition such as lowering the calcium-to-protein ratio of the cheese to make it softer and hold more moisture also contribute to loss of opacity. Nonfat mozzarella cheese curd, made using direct acidification to reduce the calcium level, becomes translucent when only a small amount of salt is added and the solubility of the casein matrix increases (Paulson and others 1998). After cooling to refrigeration temperature, the translucency of the cheese increases as the hydrophobic interactions between the proteins decreases. This change in opacity of cheese can be considered a function of the extent of internal protein aggregation that exists within the cheese matrix. When the proteins are more hydrated, they lack the scattering centers necessary for light scattering (Pastorino and others 2002).

As cheese is heated it regains its opacity and becomes white, but reverts back to being translucent upon cooling (Dave and others 2001). This is a problem when using low-fat cheese for baking on a pizza as it turns almost clear after the baked pizza is cooled, giving leftover low-fat pizza an unappetizing appearance (Metzger and others 2000a). Rudan and others (1998b) saw improved color when a fat replacer was added to reduced-fat mozzarella cheese, but they attributed this to the homogenization of the milk (Rudan and others 1998a) and recommended that only the cream portion be homogenized.

Low-fat cheddar cheese has a similar problem with opacity. Lower-fat cheeses that have been colored with annatto develop a darker orange color after cooling and overnight storage.

Limitations of standard manufacturing procedures

In reduced-fat cheeses, there is more protein matrix (compared to volume of fat) that must be cut or deformed in sensory or texture assessment and so Emmons and others (1980) proposed that the moisture level in the fat-free substance (MFFS) content of such cheeses be made higher than in full-fat cheeses. Irvine and others (1957) recommended slow cooking of curd and washing the curd to improve the flavor of low-fat cheese. Banks and others (1993) suggested using decreased cook temperature and decreased stir-out time. Other possible modifications include higher heat treatment of milk to retain denatured whey proteins in the curd that interfere with curd syneresis and partial acidification of milk prior to renneting (Merrill and others 1994). Use of adjunct culture, preacidification of cheese milk prior to renneting, addition of various fat replacers (both protein and carbohydrate based), variations in time, temperature, pH, and whey drainage have been utilized to acquire the desired properties of low-fat cheese (Drake and Swanson 1995; Fife and others 1996; McMahon and others 1996; Haque and others 1997).

Increasing cheese moisture

In the manufacture of low-fat cheese, the fat is largely replaced with moisture and protein. Since fat plays an important role during cheese making by physically blocking fusion of protein strands, having less fat in the curd will tend to produce cheeses with lower MFFS even though the gross moisture content increases, unless some intervention is made to retain more moisture in the cheese.

The common strategies for increasing moisture content of cheese include cutting the curd into larger size pieces, lower cook temperatures and times, shorter make times, and cold water washing of the curd after draining. These can be used in combination to maintain the MFFS of low-fat cheese at similar levels to full-fat cheese. Allowing the curd to become firmer before cutting has also been shown to reduce whey syneresis and hence increase curd moisture (Molina and others 2000; Johnson and others 2001). Using a highly concentrated milk would have a similar effect; and it is more difficult to expel moisture from curd made from milk concentrated 4 to 5× by ultrafiltration. Washing cheese curd with cold water (22 °C) also helps retain moisture, remove excess lactose, and solubilize calcium (Chen and Johnson 1996).

Increased agitation of curd promotes whey syneresis but it can be essential for lower-fat cheese manufacture. As fat is removed, the curd becomes denser and requires more agitation to prevent its accumulation and matting on the bottom of the vat. This can be a problem especially in enclosed vats.

Drake and Swanson (1995) suggested that modification in cheese making is the cheapest way to improve the quality of reduced-fat or low-fat cheese. They described that increasing moisture content in low-fat cheese could provide lubricity and creamy mouthfeel. Additional moisture would increase yield of low-fat cheese as well.

Control of cheese acidity and solubilization of calcium

Lower-fat cheeses are generally produced using lower cook temperatures in order to retain moisture. The most effective ways to prevent over-acidification are: higher draining pH, dilution of whey with water, or washing curd with water to remove lactose. Use of slow acid-producing cultures can also help, but the lower salt-in-water content of lower-fat cheese and the selection of modern starter cultures for fast acid production have meant that acidification cannot be controlled by salting the curd. Typically, lower-fat cheese is salted at a higher pH (pH 5.7 to 5.9) than is traditionally done for cheddar cheese (pH 5.3 to 5.4).

Higher draining pH often means that more calcium is retained in the curd. Calcium is important for controlling interactions of proteins in the cheese matrix and reducing calcium increases the hydration of the protein so there are fewer interactions between protein molecules. Thus, less energy is needed to disrupt them when heated, resulting in better melt (Paulson and others 1998). Below pH 5.0, cheese melt and stretch properties decrease apparently because of decrease in solubility of casein that overrides the effect of calcium (Ge and others 2002; Pastorino and others 2003c).

Reducing the amount of calcium bound to the casein in cheese is important for improving the properties of lower-fat cheese that are often too hard. A cheese with reduced calcium levels will be softer, have lower elastic and viscous moduli, increased meltability, and increased stretchability (Pastorino and others 2003a; Joshi and others 2004a, 2004b). Calcium content accounts for 50% or more of the variation in melting and flow properties of mozzarella cheese (Joshi and others 2004c). Low calcium in the serum phase of fresh pizza cheese, along with salt, has been reported to create an environment that favors solvation, swelling, and partial solubilization of casein fibers that weaken the curd matrix and define the cheese microstructure (Guo and Kindstedt 1995).

The most effective way to lower the calcium content of cheese is by acidifying the milk prior to renneting. This can improve the body and melting properties of lower-fat cheeses (Merrill and others 1994; Keceli and others 2006; Zisu and Shah 2007). Use of a calcium-chelating acid such as citric acid results in lower calcium content than acidifying with a noncalcium-chelating acid such as acetic acid or lactic acid but tends to give lower protein recovery in the cheese (Metzger and others 2000b). Abou El-Nour and others (2004) also saw an improvement in body and texture of lower-fat Ras cheese when citrate was added but not phosphate was added.

Improving lower-fat cheese texture

Fat globules are dispersed between protein strands that provide a solid structure to the cheese (Ustunol and others 1995). When fat decreases, the protein matrix becomes denser with less fat-globule dispersion, leading to a more compact structure. This results in lower moisture content of the cheese unless some other intervention is made, such as homogenization, adding a fat replacer (McMahon and others 1996) or incorporating denatured whey proteins into the cheese (Merrill and others 1994). Hardness, gumminess, and chewiness increase linearly, and cohesiveness and springiness decrease nonlinearly as fat content is lowered in cheddar cheese (Beal and Mittal 2000).

Homogenizing cream has been shown to improve body and texture of reduced-fat cheddar cheese (Nair and others 2000) by making the cheese less hard, rubbery, and curdy (Metzger and Mistry 1994). Such cheeses contain a larger number of small, evenly dispersed fat globules and produce a cheese with less free oil (Metzger and Mistry 1995). Lower-fat white Iranian cheese had improved texture with less elasticity and fracture stress when the cream used in its manufacture had been homogenized (Madadlou and others 2007). Homogenization of the entire volume of milk results in poor melting properties (Hekken and others 2007) and has only a small impact on increasing the MFFS content of lower-fat cheeses (Emmons and others 1980). As the fat content of cheese is reduced (especially at the low-fat cheese level) the fat globules cease to play a significant role in cheese texture.

Various additives have been investigated as fat replacers, or fat mimetics, in low-fat and reduced-fat cheeses. These include protein microparticles in cheddar cheese (Lucey and Gorry 1993; Desai and Nolting 1995; Drake and others 1996a, 1996b; Fenelon and Guinee 1997; Aryana and Haque 2001; Haque and others 2007) and mozzarella cheese (McMahon 1995; McMahon and others 1996; McMahon and Oberg 2000) and polysaccharide particles derived from starch and cellulose (Bullens and others 1994; Drake and others 1996a, 1996b; McMahon and others 1996; Aryana and Haque 2001; Haque and others 2007). Fat replacers have also been used in making lower-fat versions of kashar cheese (Koca and Metin 2004; Sahan and others 2008), white-brined cheese (Romeih and others 2002; Kavas and others 2004), feta cheese (Sipahioglu and others 1999), and Domiati cheese (El-Sheikh and others 2001; Kebary and others 2006). In fluid or semifluid food systems, such fat mimetics can impart a sense of lubricity and creaminess when the food is consumed (Romeih and others 2002), although their application in a solid food such as cheese tends to interrupt the extensive protein network that is formed when fat is absent (McMahon and others 1996; Konuklar and others 2004). Use of fat mimetics in lower-fat cheese produces a smoother protein matrix; a more finely dispersed fat network, and a less rubbery cheese (Drake and others 1996b).

Use of microparticulated whey protein in low-fat cheddar cheese was reported to improve texture in terms of elasticity, crumbliness, mouthfeel, and mouthcoating (Degouy 1993). Drake and others (1996b) observed improvement in appearance of a 60% reduced-fat cheddar cheese using a cellulose fat mimetic. Lobato-Calleros and others (2001) reported that adding low-methoxy pectin or whey protein concentrate to a reduced-fat Manchego cheese eliminated the compact and dense protein matrix characteristic of reduced-fat cheese giving a cheese with less hardness, springiness, cohesiveness, and chewiness.

Instead of using a protein or carbohydrate microparticle as the fat mimetic in cheese, it is also possible to use a water-in-oil-in-water emulsion to modify the textural properties of cheese (Lobato-Calleros and others 2008). They found that using gum Arabic or low-methoxy pectin to make the emulsion produced a reduced-fat fresh white cheese with a texture most similar to full-fat cheese.

Another alternative for mimicking the space normally occupied by fat in cheese is to use cultures that generate large amounts of polysaccharides as a capsule around the bacteria cell. Such cultures are known to reduce the amount of whey syneresis from the curd during cheese making and can increase moisture content by up to 3% (Perry and others 1997; Low and others 1998) and have been used for making low-fat mozzarella cheese (Perry and others 1998; Zisu and Shah 2007) and reduced-fat cheddar cheese (Awad and others 2005; Dabour and others 2006). They appear to function by physically blocking some of the protein strand fusion that brings about shrinkage of the curd particles during cheesemaking (Perry and others 1997; Hassan and Awad 2005). Thus, there is a less compact protein matrix structure with larger serum pockets dispersed throughout (Dabour and others 2006). Loss of polysaccharide into the whey is a concern, but very little is lost into the whey when the polysaccharides are retained as a capsule (Petersen and others 2000). Using an exopolysaccharide-producing culture has been reported to reduce springiness, increase melting and shred fusion, and reduce surface scorching during baking (Zisu and Shah 2007).

As fat plays a vital role in the overall composition of cheese, it influences salt-to-moisture ratio, texture (Lawrence and others 1987), functionality, and microstructure of cheeses (McMahon 1995). Absence of fat imparts a reduction in these qualities and the volume of water that can be retained in the cheese curd during its manufacture. Various approaches to counteracting this include manipulation of processing parameters to enhance moisture levels, control of lactose levels, increasing the surface area of the fat globules by homogenization, selection of starter cultures, use of adjunct cultures or enzymes for flavor and texture manipulation, as well as using fat mimetics to improve texture (Banks 2004). Controlling moisture and acid content of cheese are 2 critical parameters when making a low-fat cheese (Drake and Swanson 1995).

Addition of nonparticulates

Various macromolecules have been tested as fat replacers. Carrageenan was used by Gamay (1992). Pectin has also been suggested as a way to improve the properties of low-fat cheese (Liu and others 2008). Gelatin has been proposed as a fat replacer because it has the advantage of producing a thermoreversible gel at 30 °C (mouth temperature) and could improve the chewdown characteristics of low-fat cheese (Anonymous 1996). Crites and others (1997) replaced milk fat (up to 75%) with sucrose polyesters as a nonpolar fat substitute and produced cheeses that had similar pH and moisture. Replacing butter oil with sucrose polyesters produced a cheese with smaller fat droplets and a microstructure that more resembled processed cheese. Adamany and others (1999) proposed adding a polyanionic gum to media for making bulk starter culture and using this for manufacture of low-fat cheese. Sipahioglu and others (1999) obtained similar sensory scores for lower-fat feta cheese made with added tapioca starch and lecithin.

Use of barley β-glucan (Vithanage and others 2008) has been used to improve melting and stretch properties of low-fat mozzarella cheese, but was found to adversely affect the aroma and flavor of white-brined cheese (Volikakis and others 2004). Carrageenans have been used in low-fat Oaxaca cheese (Totosaus and Guemes-Vera 2008) and reduced-fat cheese (Bullens and others 1994). Microcrystalline cellulose, β-glucan, and microparticulated whey protein have been used in low-fat Kashar cheese (Sahan and others 2008). Gum tragacanth has been used in low-fat Iranian white cheese (Rahimi and others 2007). Chitosan has been used in low-fat cheddar cheese (Aryana and Beck 2007). Adding inulin to low-fat mozzarella cheese was effective in increasing softness and moisture (Pagliarini and Beatrice 1994).

In the production of mozzarella and other pasta filata cheeses, there is also the possibility of adding ingredients either to the curd prior to cooking and stretching or to the hot cheese mass afterwards, rather than adding it to the milk prior to renneting. Nelles (1999) proposed addition of a rice-based fat substitute through a kneading and spraying process that would preserve the integrity of the cheese's fiber structure to produce a low-fat pasta filata cheese.

Addition of amphiphiles

Various materials have been tested for their effect on modifying the protein matrix to improve the texture and help retain moisture in the cheese. Addition of lecithin prior to renneting produces a more open structure of the resultant lower-fat cheese and improves its texture (Drake and others 1996). Such amphiphilic materials function by masking hydrophobic sites on the para-casein strands in the cheese curd, and thus reduce the major driving force for matrix shrinkage and subsequent whey expulsion from the curd. Addition of lecithin increased the moisture content of reduced-fat cheese and increased its whiteness (Drake and others 1998). While it improved the texture of the cheese it also had a negative impact on flavor quality. Sipahioglu and others (1999) used lecithin combined with tapioca starch for making low-fat feta cheese and produced a flavor similar to full-fat cheese. Dabour and others (2006), however, did not see any improvement in texture or a difference in cheese microstructure when lecithin was used for making reduced-fat cheeses.

Buttermilk has been suggested as a potential additive that could improve texture and flavor of low-fat cheese because of the milk fat globule membrane material it contains. Mayes and others (1994) observed a slight improvement when buttermilk was added by homogenizing with cream, but did not think the effect was large enough to have commercial value. Poduval and Mistry (1999) reported improved body and texture for reduced-fat mozzarella cheese and an increase in free oil during storage. Mistry and others (1996) also saw improved body and texture of reduced-fat cheddar cheese made with ultrafiltered buttermilk (UBM) compared to a control with the same moisture content. When UBM is added to milk prior to renneting, about half of the added phospholipids in the buttermilk are retained in the cheese curd that increases the moisture content of the resultant cheese (Turcot and others 2001).


Since low-fat cheeses have a more continuous protein network with few interruptions from fat, the extent of proteolysis becomes important for developing the desired cheese texture during storage. Doubling the rennet level used in making low-fat Iranian white cheese made the cheese softer, more meltable, and improved the sensory impression of texture (Madadlou and others 2005). Using a more proteolytic coagulant increased primary proteolysis during storage in reduced-fat mozzarella cheese, but no improvement was observed in firmness or melting properties (Sheehan and others 2004). In contrast, storage at a higher temperature increased the rate of proteolysis and reduced firmness and increased heat-induced flowability.

It has generally been observed that lower flavor scores are obtained with virtually all varieties of cheese when fat content is lowered more than 50%. For example, fat content in the Greek sheep's milk cheese Kefalograviera could be reduced by half with no significant change in flavor scores, but a 75% reduction produced a cheese with lower flavor scores (Katsiari and Voutsinas 1994).

Adding enzymes to hydrolyze proteins or lipids will increase the formation of amino acids and fatty acids, although this will not necessarily produce improved flavor. El-Sonbaty and others (2002) observed that adding freeze-shocked lactobacilli was better at improving the flavor of low-fat Edam cheese than adding a protease/lipase mixture.


Salt is an important contributor to cheese flavor and when the salt content of a 50% reduced-fat cheese was increased from 1.2% to 1.8% there was increased cheddary flavor intensity and reduced bitterness; and an increased crumbly texture (Banks and others 1993). This may be a function of salt on the perception of cheese flavor or its influence on culture activity during storage, when S/M increased from about 2.5% to 3.8%. However, no differences in flavor of reduced-fat cheddar cheese were observed when cheeses with S/M of 2.7% and 4.5% were compared (Mistry and Kasperson 1998). The cheeses with the higher salt content had less proteolysis during aging and increased hardness and fracturability.


Because low-fat cheeses need to have a high moisture content and there is a limit to the amount of salt that can be added, salt content in the moisture phase of cheese is lower than the typical 4.5 to 5.5% of full-fat cheddar cheese. This change in the microenvironment is largely responsible for the shifts in the functional and sensory characteristics of the cheese (Banks and others 1993; Bryant and Ustunol 1995) as well as in its microbiology and biochemistry (Nauth and Ruffie 1995). The greater the reduction in fat the more severe these shifts are, so a 25% reduced-fat cheese will in many cases function like its full-fat counterpart, but a low-fat cheese will be quite different and reflect having a salt-in-water content of only 3.0 to 4.0%.

Many researchers have investigated the use of adjunct cultures for improving cheese flavor and, while some improvements were observed with reduced-fat cheeses, there has been no consistent beneficial effect observed in low-fat cheeses. These are usually added to provide increased secondary proteolysis and prevent bitterness that can be a problem whenever long storage of high-moisture cheeses is performed. It is a common practice in the cheddar cheese industry to lower the moisture content to 34 to 37% if the cheese is going to be aged for a long time, and to use higher moisture levels (38% to 39%) for short-hold cheese. This becomes a challenge for low-fat cheeses that need to have high moisture (52 to 55%) to have comparable hardness to full-fat cheese, but for which an aged cheese flavor is desired. Adding an adjunct culture improved the acceptability of low-fat Chanco cheese (Brito and others 2006). Katsiari and others (2002) and Michaelidou and others (2003) found improvements in lower-fat Kefalograviera cheese when adjunct cultures were added, however Gursel and others (2003) reported no improvement in flavor in low-fat pickled white cheese. Lee and others (1992) added a Micrococcus adjunct culture to reduced-fat cheddar cheese and produced a more intense cheddar flavor, less bitterness and other off flavors, and a smoother body. This may have been related to increased proteolysis when live cells of Micrococcus were added rather than a cell-free extract.

Nonstarter lactic acid bacteria

Various researchers have investigated differences between microbial populations and extent of proteolysis that occurs during ripening of full-fat and lower-fat cheeses. Data can be difficult to interpret because of the influence of moisture (especially MFFS) and salt contents of the cheeses. In general, it could be expected that as S/M content decreases, the growth of bacteria increases. Fenelon and others (2000) reported that the nonstarter lactic acid bacteria (NSLAB) populations decreased as the fat content of cheese was lowered, and proteolysis decreased during ripening. Although for their cheeses, the MFFS was lower in the lower-fat cheeses.

The extent of hydrolysis of casein during ripening cannot predict cheese flavor development. Catabolism of amino acids and production of volatile flavor compounds by the microflora (starters and NSLAB) are also important. Enhancement of flavor compounds has been shown by addition of alpha-ketoglutarate as a transaminase acceptor (Banks and others 2001). Shakeel-Ur-Rehman and others (2003) added yeast extract to promote early growth of NSLAB in reduced-fat cheddar cheese. While this did not alter the primary hydrolysis of the caseins during aging, there was an increase in free amino acids suggesting increased secondary proteolysis. There were also higher levels of NSLAB during the first 30 d of storage, and the cheeses with the added yeast extract were considered to be more mature and had higher intensities of whey, fruity, sulfur, nutty, sweet, and sour flavors, but had lower intensities of brothy flavors.

Fat-derived flavors

Emulsifying butter oil with lecithin and then manufacturing low-fat cheese can produce an increase in free fatty acids (>12 carbons) in the cheese presumably being derived from the lipolysis of the lecithin (Gonzalez and Richter 1995).

Pasteurization temperature

Using high heat treatment of milk during pasteurization to incorporate denatured whey proteins into the cheese curd for making reduced-fat Havarti cheese resulted in decreased bitterness (Lo and Bastian 1998). Guinee and others (1998), however, found little influence of pasteurization temperature on proteolysis or grading score for reduced-fat cheddar cheese.

Innovative technologies

Silver (1991) proposed plasticizing a mixture of butterfat, dairy protein, and 50% to 70% water, using high-speed cutting or ultrasonic treatment to rupture the fat globules. This would form a stable self-emulsified product based upon protein–fat interactions without addition of emulsifying agents. Miller and others (1996) proposed adding a gel-forming substance to skim milk, making cheese, and then, after aging, finely comminuting the cheese and heating to 60 °C to form a homogeneous cheese mass without the addition of emulsifying agents. Inniss and others (2006) suggested mixing cheese curd with starch as a fat substitute, and then heating it in a cooker stretcher to make a low-fat mozzarella-type cheese.

Yee and others (1998) proposed using an ultrafiltered milk concentrate containing most of the whey proteins in milk and heating it to 52 to 74 °C with low levels of shear, and rapidly cooling to make a low-fat natural cheese with improved melting properties. Schokker and others (2006) proposed making a low-fat cheese from a mixture of high-fat and low-fat components.

Imparting a high-pressure (400 MPa) treatment to milk prior to renneting had the effect of increasing protein and moisture retention in lower-fat cheese (because it accelerated coagulation producing a firmer curd), which also had faster protein degradation and flavor development and improved texture (Molina and others 2000). A different use of pressure is to age a full-fat cheese until the required flavor is developed and then use pressure to expel fat creating a lower-fat cheese with the same aged cheese flavor and flavor profile (Barbano 2004; Nelson and Barbano 2004; Carunchia Whetstine and others 2006). Extraction of fat from full-fat cheese can also be achieved using supercritical fluid extraction (Yee and others 2007).

Fenelon and others (1999) suggested blending full-fat and nonfat cheddar cheese curd particles at the time of whey drainage would produce a cheese with less hardness (yield stress) when a shredding step was included. This produced a cheese with a homogeneous distribution of fused full-fat and skim curd particles.

Low-Fat Processed Cheese

Approximately 90% of the total fat in processed cheese is derived from the natural cheese that is used in its manufacture. There are also certain minor contributions by other dairy ingredients such as dried cream and anhydrous milk fat. Therefore, utilization of a lower-fat natural cheese as an ingredient for processed cheese manufacture is one of the best ways to produce a processed cheese with a lower-fat content. Defects in the lower-fat natural cheese eventually carry over into the processed cheeses produced using them (Muir and others 1997; Gwartney and others 2002). The approximate fat content of various ingredients in a processed cheese formula is listed in Table 2.

Table 2—.  Approximate fat content of various ingredients that are used in processed cheese formulas.a
IngredientsFat contentb%PCPCFPCS
Percentage quantity (%)Fat contribution (%)Percent fat contribution from ingredients (%)Percentage quantity (%)Fat contribution (%)Percent fat contribution from ingredients (%)Percentage quantity (%)Fat contribution (%)Percent fat contribution from ingredients (%)
  1. aFormulas for PC, PCF, and PCS used from Table 1. Adapted from Kapoor and Metzger (2004).

  2. bThe fat content for the ingredients were obtained from: natural cheese = typical fat content of cheddar (USDA National Nutrient Database for Standard Reference [USDA 2008]); dried cream = minimum fat content specified by CFR (21CFR131.149); NDM = maximum fat content specified by CFR (21CFR131.125); whey powder = maximum fat content specified by CFR (21CFR184.1979); whey protein concentrate (WPC) (value obtained from nutrient data sheet of a commercially available WPC-80).

Natural cheese33.0 80.3026.5 86 70.9023.4 94 60.0019.8 94
Dried cream40.0  5.80 2.3  8  0.00
Nonfat dried milk (NDM) 1.5  3.00  4.00 0.1
Whey powder 2.0  5.00 0.1  3.60 0.1
Butter oil (anhydrous)99.8  1.90 1.9  6  1.40 1.4 6  0.95 1.0  5
Whey protein concentrate10    1.50 0.2  1
Emulsifying salt(s)  2.50  2.50  2.25
Salt  0.50  0.60  0.80
Acidifying agent(s)  0.30
Mold inhibitor  0.20
Water  9.00 16.60 26.40
Total 100.0030.7100100.0024.9100100.0021.2100

Challenges in fat reduction in processed cheese

A 25% fat reduction in order to satisfy a reduced-fat claim for processed cheese is comparatively easier to achieve by eliminating fat contributions from other fat-rich dairy ingredients and replacing them with suitable fat replacers. However, it can be concluded that production of processed cheese with a higher fat reduction involves the successful production of a lower-fat natural cheese base with acceptable textural and sensory properties. The past research also highlights various challenges associated with the production of a lower-fat natural cheese with regards to its flavor and texture. In spite of numerous research efforts to develop lower-fat processed cheeses there are presently very limited reduced-fat, low-fat, or fat-free processed cheeses that are sold throughout the world (GNPD 2008). Moreover, their acceptance among consumers is questionable. One of the major challenges involved with the production and sale of processed cheese with lower-fat content includes the lack of availability of large-scale consumer acceptability studies for lower-fat processed cheeses in the literature such as the one conducted by Drake (2008) in natural cheese.

Although fat replacers such as Simplesse® and Dairy-Lo® are approved for use in dairy products, the labeling status of most of the fat replacers is largely unknown (Akoh 2002). Also, even though hydrocolloids are allowed in PCS at 0.8% of the final product, they are not in the standard of identity PC and PCF. Therefore, another challenge involved in the successful production of lower-fat processed cheeses that utilize fat substitutes and fat mimetics are the issues with regards to labeling (FDA 2008a).

Sensory attributes of low-fat processed cheese

Muir and others (1997) studied the sensory characteristics of 16 commercial PCS samples. The samples were selected so as to include different brands as well as the full-fat, reduced-fat, and/or low-fat versions within each brand. Concentrating on the results of one particular subset of the samples from their data where they compared full-fat PCS (58% moisture, 21% fat) with reduced-fat PCS (60% fat reduction, 63% moisture, and 8.4% fat) and low-fat PCS (63% moisture, 3% fat) from the same manufacturer, they found that as the fat content of the PCS decreased, there was a decrease in the creamy attribute and an increase in the acid and bitter attributes of the PCS. Moreover, with the decrease in the fat content there was an increase in the graininess and stickiness of the PCS. Reduction in the fat content of PCS also led to a decrease in the spreadability and the overall sensory acceptability of the PCS. Therefore, major research in the area of fat reduction in processed cheese over the years has focused on producing a reduced-fat, low-fat, and/or fat-free natural cheese base. This could then be used to manufacture a processed cheese that has a lower fat content without compromising its texture, flavor, and functional properties (Raval and Mistry 1999; Mistry 2001; Banks 2004; Lee and others 2006; Hassan and others 2007; Metzger and Kapoor 2007; Lucey 2008). Consequently, research has also involved (in conjunction with using a lower-fat cheese base) incorporation of various fat replacers at various levels in a processed cheese formula in order to successfully produce a processed cheese with acceptable texture, flavor, and functional properties. Akoh (1998, 2002) has extensively described the characteristics and the regulatory status of various fat replacers that are available in the market for such applications.

Research initiatives on reducing fat in processed cheese

The research initiatives for the production of lower-fat processed cheese can be categorized into the following 2 major areas or their combinations: (a) production of a lower-fat natural cheese base for processed cheese manufacture; (b) utilization of fat replacers in the processed cheese formula.

There are numerous challenges in terms of texture and flavor that are associated with the production of natural cheese with a lower-fat content (described previously). Research initiatives to produce a lower-fat natural cheese base with acceptable texture, flavor, and functional properties have involved utilization of modified manufacturing protocols so as to increase the moisture retention of the lower-fat natural cheeses. These initiatives include utilization of lower cooking temperatures, cold-washing of the curd, high draining and milling pH, homogenization of the cheese milk or the cream part of the cheese milk prior to natural cheese manufacture, incorporation of buttermilk/ultrafiltered sweet buttermilk/denatured whey proteins into the cheese milk prior to natural cheese manufacture, and selection of exopolysaccharide (EPS)-producing starter bacteria (Drake and Swanson 1995; Raval and Mistry 1999; Mistry 2001; Banks 2004; Hassan and others 2007; Metzger and Kapoor 2007). The important thing to note in the case of development of lower-fat processed cheeses is that the issues with the flavor can be controlled and rectified by selecting appropriate enzyme-modified cheeses and other permitted flavor enhancers. However, there is still a lack of available literature on the success of enzyme-modified cheese in lower-fat processed cheeses.

Use of ultrafiltered buttermilk

Raval and Mistry (1999) in their study manufactured reduced-fat cheddar cheese with UBM (3.5% fat, 14.3% total protein, 24% total solids) that was combined with the regular cheese milk (1.34% fat) at the rate of 5% addition to the cheese milk. This cheese was then used to manufacture reduced-fat processed cheese (50% fat reduction, 15% fat, 48% moisture) at 3 different emulsifying salt levels (trisodium citrate at 0.5%, 1.25%, and 2.0%). The experimental processed cheeses were compared to their reduced-fat control counterparts (15% fat, 48% moisture) that were manufactured with reduced-fat cheddar with no added UBM to the cheese milk. The authors evaluated the processed cheeses for various functional properties such as free oil formation, meltability, firmness, and apparent viscosity. Their results indicated that processed cheeses that utilized UBM cheddar showed lower free oil formation and were less meltable when compared to the control processed cheese at all levels of emulsifying salts. Moreover, the experimental processed cheese had a higher apparent viscosity when compared to the control processed cheese at all emulsifying salt levels. They attributed these results to the formation of a processed cheese with a stronger emulsion due to the incorporation of UBM. UBM is a rich source of milk fat globule membrane material that contains phospholipids that can act as natural emulsifiers thereby leading to a stronger emulsion. Their study, however, did not include any comparisons of the experimental processed cheese with a full-fat reference.

Manipulating the starter cultures

Hassan and others (2007) studied the effect of EPS-producing starter cultures to manufacture reduced-fat cheddar cheeses (approximately 35% fat reduction). These reduced-fat cheddar cheeses were utilized to manufacture reduced-fat PC (approximately 30% fat reduction, 21% fat, 49% moisture). The experimental processed cheeses manufactured were compared to a reduced-fat PC control (21% fat, 49% moisture).

All PCs were evaluated for textural, functional, and sensory properties. Reduced-fat PC produced with reduced-fat cheddar utilizing EPS-producing starter cultures had an overall softer texture and were more flowable when compared to the control. Moreover, the experimental PC had similar sensory acceptability scores to the control. Utilization of EPS-producing starter to manufacture a lower-fat cheese base for processed cheese manufacture may be a promising avenue since development of EPS in the cheese structure may lead to inherent fat mimetic properties and, therefore, may solve various textural issues associated with lower-fat processed cheeses without significantly affecting the sensory properties of the final product. Their study failed to draw comparisons with a full-fat PC reference (Hassan and others 2007).

Use of reduced-fat cheddar cheese

Metzger and Kapoor (2007) manufactured a reduced-fat Cheese base (12.3% fat, 53% moisture, and pH 5.4) using a combination of cream, homogenization, cold-washing of the curd, and higher pH at salting. This cheese base after 1 wk of ripening had a bland clean flavor and a texture similar to full-fat cheddar. About 74% of this cheese was then used to manufacture a reduced-fat PCF slice-type product (12% fat, 49% moisture, pH 5.6) along with other ingredients such as enzyme-modified cheeses and guar gum (0.2%). The firmness and meltability of the reduced-fat PCF were measured and compared to a commercial full-fat and a reduced-fat PCF slice samples. Their results indicated that the experimental PCF was firmer and less meltable when compared to both the commercial samples. In a recent study to optimize the successful manufacture of a reduced-fat PC for slice-on-slice applications, a fat-free natural cheese base was developed (1.25% fat, 54% moisture, 38% protein). This cheese was subsequently used to develop 4 slice-on-slice PC formulations involving full-fat, 25% reduced-fat, 50% reduced-fat, and low-fat at the levels of 47%, 58%, 61%, and 67% of the total formula, respectively. Other ingredients in the formulations involved 12% full-fat aged cheddar cheese, butter, water, trisodium citrate, fat mimetic, and salt. The study indicated a successful manufacture of the 4 PC products (Metzger 2008).

Utilization of fat replacers in the processed cheese formula

According to Akoh (1998), fat replacers can be classified as fat substitutes and as fat mimetics. Fat substitutes are generally lipid-based macromolecules that physically and chemically resemble fats and oils such as sucrose fatty acid esters and polyesters, carbohydrate fatty acid esters, various emulsifiers (such as mono- and diglycerides, lecithin), and structured lipids (such as medium-chain triglycerides, Salatrim). Fat mimetics are generally carbohydrate-based (modified starches and hydrocolloids) or protein-based (Simplesse®, Dairy-Lo®, and others) macromolecules that are designed to mimic the organoleptic and physical properties of fats generally via binding of water.

According to the CFR, hydrocolloids are allowed as an ingredient in PCS (FDA 2008a). One of the earlier works to study the utilization of hydrocolloids to produce reduced-fat PCS was performed by Brummel and Lee (1990). They evaluated various hydrocolloids (guar gum, 60DE pectin, 65DE pectin, 73DE pectin, λ-carrageenan, propylene glycol alginate, xanthan gum, and zooglan) at different levels to achieve PCS with 40% and 50% fat reduction (when compared to the full-fat control PCS with 25% fat and 48% moisture). The experimental PCS batches were evaluated for texture and sensory characteristics and compared to the control.

Their results indicated that 40% reduced-fat PCS (15% fat, 60% moisture) with 1.7% 60DE pectin was the closest to the control. However, it had a lower firmness as well as a slightly lower melt when compared to the full-fat control. Moreover, control had higher sensory scores for cheese flavor, richness, and overall preference. Firmness results indicated that reduced-fat PCS made with all the hydrocolloids except the ones with 60DE, 65DE, and 73DE pectins at 3.6% and 4.1% had a lower firmness when compared to the control. Swenson and others (2000) manufactured fat-free PCS (0.6% fat, 59% moisture) using 2% hydrocolloids including gelatin, carrageenan, locust bean gum, and guar gum and compared the firmness, meltability, and spreadability of their experimental PCS to the full-fat control. The fat-free PCS formulation included 60% hard skim milk cheese as the cheese base, 3% disodium phosphate as the emulsifying salt, and various hydrocolloids at 2%. The formulation of their full-fat PCS used full-fat cheddar instead of the hard skim milk cheese and did not contain any hydrocolloids.

The results from their study showed that all the fat-free PCS had significantly higher firmness, lower melt, and lower spreadability when compared to the full-fat reference. In the same study, Swenson and others (2000) also studied the effect of various emulsifying salts, cook time and temperature, and the pH on the firmness, meltability, and the spreadability of the fat-free PCS (with no added hydrocolloids). They found that fat-free PCS manufactured using 3% trisodium citrate was more meltable than the full-fat reference, however had significantly less spreadability. The fat-free PCS made using 3% disodium phosphate was significantly less meltable when compared to both the fat-free PCS manufactured using 3% trisodium citrate and the full-fat reference. They also found that as the cook time and temperature were increased during the manufacture of the fat-free PCS, its meltability and spreadability increased. Moreover, when the final pH of the fat-free PCS was increased from 5.26 to 6.88, its meltability and its firmness increased, however its spread decreased. There have been other instances in the processed cheese industry where various workers have used different hydrocolloid mixtures and other fat mimetics to successfully manufacture processed cheese products (Gamay 1991; Davison and others 1993; Rybinski and others 1993).

Muir and others (1999) evaluated 3 different fat mimetics—microparticulate whey protein-based Simplesse® and Dairy-Lo® and modified starch-based Paselli®— in an imitation cheese formula and compared it to a full-fat control (23% fat, 56% moisture) that was made using anhydrous milk fat as the fat source. All the cheeses were evaluated for various sensory characteristics. Their results showed that they were able to successfully manufacture reduced-fat cheeses (approximately 43% fat reduction) with the 3 fat mimetics. Their sensory results showed that all the reduced-fat cheeses were significantly less creamy, less buttery, and more bitter when compared to the full-fat control.

Past research has also shown the utility of different fat substitutes for the successful manufacture of lower-fat processed cheeses and processed cheese-type products. Kong-Chan and others (1991) and Mehnert and Prince (1996) have indicated the utilization of sucrose fatty acid esters and polyesters at various levels to successfully manufacture lower-fat processed cheeses and processed cheese-type products. Other fat substitutes such as lecithin (allowed as an antistick agent in processed cheeses) and mono- and diglycerides have also been used to manufacture processed cheeses (Drake and others 1999; Lucey 2008).

Drake and others (1999) used granulated soy lecithin at various levels (0.025%, 0.05%, 0.1% and 0.2%) to manufacture reduced-fat PC and compared the texture as well as sensory results to a full-fat PC, as well as a reduced-fat PC with no added lecithin. Their results indicated that reduced-fat PC with 0.05% granular soy lecithin improved the texture properties without significantly affecting their sensory acceptability. They also found that the reduced-fat PC with added lecithin was more similar to the full-fat PC than the reduced-fat PC with no added lecithin. Lucey (2008) utilized emulsifiers (mono- and diglycerides) at various levels to manufacture fat-free processed cheese products utilizing a novel technology. He concluded that addition of mono- and diglycerides to the processed cheeses product improved the melt, stretch, slicing, and shredding abilities, and produced a product with a clean flavor.

Sodium Reduction in Natural Cheeses

Challenges for low-sodium natural cheese

Reducing the sodium chloride content of cheese presents particular challenges to cheese makers since salt has many roles in cheese. It has been an integral component in cheese, used to maintain expected flavor, body, texture, and shelf life by controlling the activities of enzymes and microorganisms. Consumers expect some degree of saltiness in cheese. Yet, many are requesting lower-sodium cheeses or else they will remove cheese from their diet. While efforts have been made to market a table cheese, that is, cheese eaten directly as a snack or food, perhaps the direction should be more for use of low-sodium cheeses as ingredients.

Cheese also has many positive nutritional attributes, including minerals such as calcium and potassium. These minerals may offset negative contributions of sodium chloride in the diet. Directing efforts to overcome the human behavioral response to reduced-sodium products will be exceptionally challenging, especially in adults already conditioned to desire salt. Reduction of sodium in a single food such as cheese, but without reduction in sodium chloride in other foods, may negate any potential to condition adults to eat fewer sodium-chloride-containing foods.

Replacing a portion of the added sodium chloride in cheese with other chemicals to give the perception of saltiness may eventually have success, especially with mild flavored cheeses. However, this approach may not provide the cheese makers with a means to control the growth and metabolism of both desirable and undesirable bacteria and this will make it difficult to develop desired flavors in cheese. The challenge will be for dairy technologists to develop and/or use ingredients, microorganisms, and enzymes that can result in the desired cheese.

Consumer acceptance

Consumers have become accustomed to the idea that certain foods will have a degree of salty taste. Cheese is no exception. There is a line item on the USDA cheese-grading scorecard that asks the cheese grader to ascertain whether the salt contribution to the overall flavor of the cheese is too high or too low. However, since there are no federal standards of identity (other than specific labeling as reduced or low sodium) for salt content of any cheese, the saltiness attribute is at the discretion of the grader.

Schroeder and others (1988) evaluated cheddar cheese and the reduction of sodium chloride beginning from 1.44 to 1.12, 0.73, 0.37, and 0.07%. Consumers (40) tasted the cheese and rated it on a 9-point scale over a 7-mo period. Regression analysis showed saltiness was the one most important attribute driving consumer ratings of overall desirability. This was cheese made and aged at these salt concentrations. The authors noted that cheddar intensity and lack of unpleasant aftertaste may have driven the desirability ratings toward the high-salt cheeses.

Banks and others (1993) reported that in reduced-fat cheddar cheese (about 16% fat) a lower salt content (1.25%) produced a bitter cheese with less cheddar flavor than one with a higher salt content (about 1.8% salt). However, the higher salt content produced a firmer low-fat cheese. Similar observations on bitterness and firmness were reported by Mistry and Kasperson (1998). They also noted that with a salt content of 2% the texture of the cheese was compromised (too firm). Cheeses at all salt levels, (1.31, 1.71 and 2.04% salt), however, had similar sensory scores (7 out of a maximum 10). It should be noted, however, that none of these would have met the FDA standard for low-salt cheese.

Rutikowska and others (2008) manufactured Irish cheddar cheeses with salt levels ranging from 0.5% (low salt) to more traditional 3.0%. The starter bacteria and NSLAB survived significantly longer in the cheeses with 0.5 and 1.25% salt than in cheeses with 1.80% or more salt. The 2 lower-salt cheeses also had less pep X activity resulting in a lower rate of flavor formation and a higher bitterness evaluation.

In a recent study, Phan and others (2008) concluded that sodium release during mastication is mainly influenced by matrix structure and composition, particularly moisture content, while saltiness perception is limited by the presence of fat. They also concluded that a way to reduce salt in cheese without a detrimental impact on flavor would be to increase the moisture and decrease the fat. They also suggest that a balance has to be found between composition and structure to produce cheeses according to nutritional recommendations and acceptability by consumers in terms of salty perception.

In order to separate ripening effects from taste perception effects of salt, Drake and McMahon (unpublished data) prepared re-formed cheeses with 1.0, 1.4, 1.8, 2.2 and 2.6% salt. Consumers documented differences in salty taste intensity between all salt concentrations except 2.2 and 2.6%. Salty taste liking suggested that salt concentrations of above 1.8% resulted in cheeses with acceptable taste intensity. Flavor liking scores suggested that 2.2 or 2.6% might be optimal salt concentrations and that higher salt concentrations may be desirable in low-fat cheese. These results indicate that a salt reduction of as little as 25% from typical salt content (1.8% to 1.4%) are noticed by consumers and may negatively impact acceptance. Clearly, more consumer level research would be necessary to resolve these differences.

Sodium reduction in natural cheese manufacturing

The impact of reducing sodium chloride in cheese and the methods to do so has been reviewed (Reddy and Marth 1991; Guinee and O'Kennedy 2007). Lawrence and others (1984) recommended 4.5 to 6.0% S/M in their review of New Zealand cheddar cheese. Guinee and O'Kennedy (2007) have summarized the key control parameters for the production of good-quality Irish cheddar cheese. Among them are S/M values in the range of 4.7% to 5.7%, which is equivalent to a salt content of 1.7 to 2.1% (337 to 416 mg Na per 50 g cheese) in 37.5% moisture cheddar. As noted earlier, low-sodium cheddar would allow for a maximum of 140 mg of sodium per 50 gm.

The higher-salt cheeses (2.5% to 3.5% salt) such as blue, Romano, parmesan, and feta are expected to be salty. The high salt content of blue cheese is one aid in selecting growth of the desired mold, Penicillium roquefortii, rather than allowing salt-sensitive and sometimes defect-causing microorganisms to grow. In the case of feta, a rather high-moisture cheese, salt slows the growth of undesirable microorganisms and slows the undesirable proteolytic activity that would eventually result in a cheese with excessive softness. Parmesan cheese is a low-moisture cheese and, together with a high salt content, has an extended shelf life of several years. Much of the flavor of Parmesan cheese is due to the action of lipase at low water activity/low water content. The activity and specificity of these enzymes at lower water activity cause the characteristic fruity flavor notes at a higher rate than at high water activity (Fenster and others 2003).

Lower-salt cheeses (0.9% to 1.2%) such as Swiss and fresh mozzarella are not expected to be salty and higher salt contents may detract or even prevent the development of the desired flavor and cheese characteristics. The eyes in Swiss cheese result from the metabolism (gas formation) of added Propionibacterium, which do not grow at higher salt levels. In fresh mozzarella, the desired delicate, milky, sweet flavors derive mainly from the milk and even intermediate salt levels would add an undesirable salty note.

Concerns regarding reducing sodium chloride on cheese quality are based on 2 broad areas: direct flavor contribution and control of growth and metabolic activity of both desirable and undesirable microorganisms and enzymes. The reason salt plays such an important role in cheese quality is due to its impact on the rate and extent of sugar fermentation and thus the final pH obtained in the cheese during the initial period of aging and higher levels inhibiting proteolysis (Thomas and Pearce 1981). Proteolysis is necessary for proper flavor and body development. Excessive or insufficient fermentation or proteolysis can lead to defects of both flavor and body of cheese. At about 1.5% salt, 5% of the alpha-casein and 50% of the beta-casein were not hydrolyzed, while at 2.1% salt, 30% of the alpha-casein and 80% of the beta-casein were not hydrolyzed (Thomas and Pearce 1981). It is for this reason that cheddar cheese manufacturers aim for the intermediate 1.7% salt content of their cheeses.

Use of salt substitutes in natural cheese

There are 2 general means to control the amount of sodium in cheese. One is simply to restrict the addition of sodium chloride. The other is to use salt substitutes that contain little or no sodium but that give a taste similar to sodium chloride. Potassium chloride (KCl) is the most chemically similar compound to sodium chloride and is the most obvious choice for NaCl replacement. KCl must be included on the label (milligram of potassium per serving).

Lindsay and others (1982) reported that consumers were able to recognize, and therefore prefer, higher-sodium-chloride cheeses (1.75% sodium chloride) over cheese with less salt (1.5 and 1.25% sodium chloride) and over cheese with partial substitution of KCl (1:1 molar basis). Commercial medium-aged cheese was compared to medium lower-salt cheddar. About 85% of the panelists thought that the medium-salt cheese (264 mg sodium per 50-g serving) was as good as or better than the commercial sample (364 mg sodium per 50-g serving). While only 65% of the panelists thought that the lower-salt cheese (214 mg sodium per 50-g serving) was as good as or better than the commercial cheese. It was also the author's assessment that sodium reduction with added KCl (145 mg per 50-g serving) might encounter considerable consumer resistance and be less well received than lower-sodium-chloride cheese (214 mg sodium per 50-g serving). It should be noted that after 9 mo of aging there were a considerable number of panelists who scored the lower-sodium-chloride cheese (26 out of 150 panelists) and the low-level blend of NaCl/KCl (22 out of 150 panelists) as “like very much” compared to 42 of 150 panelists who very much liked the cheese with 1.5% sodium chloride. An interesting comment was that successful marketing of these cheeses for direct consumption (not as an ingredient) would depend upon a consumer group with strong, health-related motivations.

Fitzgerald and Buckley (1985) evaluated the impact of cheddar cheese produced with different salt substitutes at equivalent ionic strength of the control sodium chloride level (1.5%). Use of magnesium chloride, potassium chloride, or calcium chloride at this level produced an extremely unacceptable cheese (bitter taste, metallic flavor, and crumbly body). Proteolysis and lipolysis were highest in these cheeses also. A 1:1 mixture of sodium chloride and magnesium or calcium chloride also produced unacceptable cheeses. However, a mixture of 1:1 ratio of sodium chloride and potassium chloride resulted in a cheese comparable to the control (sodium chloride only). It must be noted that in this report the mean flavor scores of the control and blended-salt cheese had numerical scores of 4.5 and 4.4, respectively, of 8 (like very much) and the texture scores were 4.5 and 4.2 for the control and blended-salt cheeses, respectively.

Sodium Reduction in Processed Cheese

The 3 major ingredients that contribute to sodium in processed cheese are sodium-based emulsifying salts (approximately 44% to 48%), natural cheese (approximately 28% to 37%), and added salt (approximately 15% to 24%). Therefore, sodium reduction initiatives in processed cheese involve mainly the modification of 1 or all 3 ingredients during processed cheese formulation and manufacture. Numerous research efforts in the past have been targeted toward the development of reduced- and/or low-sodium natural cheese as an ingredient for processed cheese (Karahadian and Lindsay 1984; Metzger and Kapoor 2007). Efforts have also been directed at the development of novel formulations in order to utilize potassium-based emulsifying salts (Gupta and others 1984; Karahadian and Lindsay 1984; Henson 1997; Metzger and Kapoor 2007), various salt replacers, and other flavor enhancers (Karahadian and Lindsay 1984; Metzger and Kapoor 2007) without causing a detrimental effect on the flavor, sensory, and functional properties of the final processed cheese.

Lack of information In spite of numerous research efforts to develop reduced-sodium processed cheeses there are presently no reduced- or low-sodium processed cheeses that are sold in the marketplace throughout the world (GNPD 2008). One of the major challenges involved with production and sale of processed cheese with reduced-sodium content includes the lack of availability of large-scale consumer acceptability studies for reduced-sodium processed cheeses in the literature. In addition, production of low-sodium processed cheese (≤140 mg/50 g sodium) seems to be more challenging due to the fact that there are no concrete research efforts available in the literature that indicate the successful development of a low-sodium processed cheese.

Safety of processed cheese Another area that acts a bottleneck in the production and sale of reduced-sodium processed cheeses is the safety concerns associated with their production for shelf-stable applications. Processed cheese falls into the category of low-acid canned foods due to its chemical composition and pH. Therefore, anaerobic spore-forming organisms such as Clostridium spp. are one of the major concerns in processed cheese (Glass and Doyle 2005). For shelf-stable applications, processed cheese relies heavily on thermal processing to eliminate vegetative pathogens and on formulation parameters to prevent growth and toxin production from spore-forming pathogens (Tanaka and others 1986; Glass and Doyle 2005). Tanaka and others (1979, 1986) have shown the inhibitory effects of sodium phosphate-based emulsifying salts in combination with pH, water activity, and NaCl and consequently have developed models to ensure the microbiological safety of processed cheese that are produced for shelf-stable applications.

According to Tanaka and others (1986), for a shelf-stable processed cheese spread (56% moisture and pH 5.5), the total NaCl + disodium phosphate (DSP) in the final spread must be approximately 4% in order to render the product microbiologically safe. Such formulation limitations for shelf-stable processed cheeses discourage any formulation changes from a product development standpoint. It is understandable that potassium-based phosphate emulsifying salts may be able to replace DSP in such formula; however, there are no food safety-related challenge studies available to quantify the effectiveness of these salts in processed cheeses (Karahadian 1984).

The effects of emulsifying salt substitutes on processed cheese functionality Traditionally, the successful manufacture of processed cheese has been largely dependent on the function of sodium-based emulsifying salts (Gupta and others 1984; Caric and others 1985; Shimp 1985; Berger and others 1998; Zehren and Nusbaum 2000). As described in an earlier section, sodium-based emulsifying salts such as DSP and trisodium citrate (TSC) sequester calcium and adjust pH during processed cheese manufacture. These functions of the emulsifying salts consequently help in providing processed cheese with its unique microstructure and functional properties. Therefore, one of the concerns related to replacing sodium-based emulsifying salts with their sodium-free counterparts (mainly potassium-based) is the effect of these emulsifying salts on the microstructure and final functional properties of the resulting processed cheese. Another concern associated with utilization of potassium-based emulsifying salts is their effect on the flavor and sensory properties such as a decrease in the overall saltiness and development of bitter and chemical-metallic off-flavors in the final processed cheese (Gupta and others 1984; Karahadian and Lindsay 1984; Henson 1997).

Gupta and others (1984) extensively evaluated the functional as well as the sensory properties of processed cheese manufactured using dipotassium phosphate (DPP) and tripotassium citrate (TPC) and compared them to processed cheese manufactured using DSP and TSC. They made 4 PC batches (39% moisture, 31% fat) with 2.1, 2.2, 1.9, 1.9% of DSP, DPP, TSC, and TPC (anhydrous basis), respectively. The other ingredients in the formula included cheddar cheese (a blend of 75% young (3 to 6 wk old, 32.7% moisture, 304 mg/50 g sodium) and 25% aged (1-y old, 36.3% moisture, 367 mg/50 g sodium)) and water (4%). The calculated values of sodium for their 4 PC treatments were approximately 622, 307, 542, and 307 mg/50 g (sodium contents were calculated from the sodium contribution of the ingredients in their formulations) for PC manufactured using DSP, DPP, TSC, and TPC, respectively.

Their results indicated that meltability of the PC made with DSP and DPP were similar; however, PC manufactured using TSC had a higher meltability when compared to PC made with TPC. Meanwhile, PC manufactured using TPC had a higher meltability than the PC manufactured using DPP. Also, PC manufactured using DPP and TPC had a lower firmness when compared to PC manufactured using DSP and TSC, respectively. Sensory results from their study indicated that the PC produced using the 2 citrate-based emulsifying salts were less salty, and also had lower chemical phosphate-type notes when compared to the PC made with DSP and DPP.

Also, DPP contributed to higher chemical-phosphate notes when compared to DSP in the final PC. The saltiness intensities of PC produced using DPP and TPC were similar to the PC made using DSP and TSC, respectively. Henson (1997) successfully replaced part of the DSP in their processed cheese formula (38% moisture and 31% fat) with DPP and tricalcium phosphate (TCP) to produce processed cheese with approximately 50% reduced-sodium content when compared to their full-sodium reference with no detrimental impact on the overall sensory acceptability of the product.

Using low-sodium cheddar cheeseKarahadian and Lindsay (1984) prepared and evaluated various reduced-sodium processed cheese formulations (55% and 75% sodium reduction when compared to the full-sodium reference containing 625 mg/50 g sodium) utilizing cheddar cheeses with different salt levels (sodium content), a combination of DPP and TPC to replace DSP as emulsifying salts, KCl to replace added salt, as well as the addition of other ingredients to enhance the cheese-type notes such as enzyme-modified cheese, delta-gluconolactone, and various organic acids. All the experimental PC formulations were evaluated for body, texture, and flavor attributes against a full-sodium control.

In the first part of their study, Karahadian and Lindsay (1984) manufactured 4 PC formulations with 75% sodium reduction. Two of the formulations used unsalted or lightly salted cheddar cheese (salted at the rate of 0 and 0.6% or 0 to 0.47% calculated NaCl in the final cheese, calculated from the sodium content of the cheeses). In the remaining 2 formulations, they utilized moderately salted cheddar cheese (salted at the rate of 1% salt or 0.7% calculated NaCl in the final cheese) and cheddar cheese salted with Lite Salt® (Morton, Chicago, Ill., U.S.A.) (NaCl:KCl = 1:1) at the rate of 2.1% (1.26% calculated Lite Salt® or 0.63% NaCl in the final cheese). The sodium reduction in these 2 formulations was achieved by utilizing potassium-based emulsifying salts. They found that when unsalted or lightly salted cheese was used for producing 75% reduced-sodium processed cheese, the resulting processed cheese was less firm and less salty when compared to the processed cheeses made using cheddar cheese that was moderately salted or salted using Lite Salt®. Moreover, the processed cheese made using unsalted cheddar had an unpleasant chemical-like off-flavor. Therefore, it was concluded that the approach of sodium reduction in processed cheese by utilizing unsalted or lightly salted cheddar cheeses (using cheese that had a final salt content of less than approximately 0.7%) as the major source of sodium reduction leads to the production of processed cheese with poor body and flavor characteristics.

In the second part of their study, Karahadian and Lindsay (1984) prepared 3 experimental PC formulations (38% moisture, 31% fat). Formulation 1 was a full sodium control (625 mg/50 g sodium) and used 90.8% cheddar cheese (3 wk old, salted at the rate of 2.5% with NaCl), 2.07% DSP, and 1.86% enzyme-modified cheese. Formulation 2 was 55% reduced sodium formula (286 mg/50 g sodium) and used 90.8% cheddar cheese (3 wk old, salted at the rate of 2.5% with NaCl), 1.39% TPC, 0.46% DPP, 1.86% enzyme-modified cheese, 0.46% delta-gluconolactone, and 0.23% KCl. Formulation 3 was 75% reduced sodium formula (179 mg/50 g sodium) with 90.8% cheddar cheese (3 wk old, salted with Lite Salt® at the rate of 2.1%), 1.16% TPC, 0.46% DPP, 0.23% TSC, 1.86% enzyme-modified cheese, 0.33% delta-gluconolactone, and 0.23% KCl.

All PC products were evaluated for meltability and sensory properties. The results from their study indicated that all PC samples had similar meltability and sliceability. Moreover, the 2 reduced-sodium formulations performed similar to the full-sodium control in commercial processing using a casting line to produce individually wrapped slices. Sensory results indicated that saltiness intensities and other body characteristics of the 3 PC batches were not significantly different. However, chemical-metallic off-notes were higher in both the reduced-sodium formulations when compared to the full sodium control. The consumer acceptability study of the cold PC as well as in a toasted application showed that the 2 reduced-sodium formulations were as acceptable as the full-sodium control. Therefore, Karahadian and Lindsay (1984) concluded that appropriate selection of cheddar cheese along with potassium-based emulsifying salts as well as other minor ingredients to enhance different flavor notes in the final processed cheese may produce PC with up to 75% reduced-sodium content and good functional as well as sensory properties.

Use of low-sodium and low-fat cheddar cheese In a recent study to produce a low-sodium reduced-fat processed cheese product, Metzger and Kapoor (2007) successfully developed a reduced-sodium, reduced-fat cheddar cheese ingredient (1 wk old, 53% moisture, 12.3% fat, 5.36 pH, 97 mg/50 g sodium and 245 mg potassium/50 g cheese) using modified manufacturing protocols. At 1 wk of ripening, this Cheese had a texture similar to full-fat regular-sodium cheddar and also lacked bitter metallic type off-flavors that are typically associated with reduced-sodium cheeses. This cheese, at 1 wk of ripening, was used to manufacture a low-sodium reduced-fat processed cheese product at approximately 74% of the final processed cheese formula. The other ingredients included TPC as the emulsifying salt, water, maltodextrin, guar gum, cheese flavors, savory flavor enhancer, KCl-based salt substitute, sugar, and lactic acid. The results from their study indicated a production of a sliceable processed cheese product with low sodium content (140 mg/50 g) and up to 67% reduced-fat content without significantly affecting its sensory and textural properties. However, their work did not include consumer acceptability studies for the processed cheese product.

Use of traditional emulsifiers Another approach to reduce the utilization of sodium-based emulsifying salts in a processed cheese formula may involve utilization of different traditional emulsifiers such as mono- and diglycerides at various levels (Lucey 2008; Paulus 2008). Lucey (2008) formulated a reduced-fat mozzarella-type product using mono- and diglycerides at various levels and showed improved meltability and stretching-ability of the final product produced when compared to the control.


Over half of American adults would like to buy low-fat cheese if it is similar to full-fat cheese, but consumers are not willing to sacrifice quality to achieve low-fat consumption. Based on actual consumer trials, cheddar cheese with 8.5 g fat/50g (50% reduction) seems to be the current technological limit while still achieving satisfactory sensory acceptance. This cheese did not meet the low-fat standard of 3 g/50 g but did meet the reduced-fat standard. Cheeses with 50% fat reduction are generally available to consumers. To achieve higher levels of fat reduction, significant technological advancements are needed. There are naturally low-sodium cheeses, such as Swiss, available to consumers. In other natural and processed cheeses, the best current option is to replace sodium salts with sodium/potassium blends. However, use of potassium salts is limited by the development of metallic, bitter, and other off-flavors. Other concerns with lower-sodium cheeses that must be overcome include food safety, quality, and functionality. With the current 50-g rule, the sodium level in cheddar, mozzarella, and processed cheeses would have to be reduced by 55%, 47%, and 80%, respectively, to achieve low-sodium status. Without the 50-g rule, the reductions would be 25%, 13% and 67%, respectively. Such a change would enable cheese makers to more easily manufacture low-sodium products, provide consumers with more options to reduce their intake of sodium, and accurately reflect consumer sodium consumption. Reducing fat and sodium in cheese, while maintaining quality and safety, continues to be a challenge for the dairy industry, worldwide.