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.
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.