Food Technological Applications for Optimal Nutrition: An Overview of Opportunities for the Food Industry
Abstract: An increasingly important determinant in food choice is the growing consumer concern about nutrition and health. This focusing of consumer interest on the food supply, and also extensive research and technological developments in food science will provide further opportunities for new product development. The Food-Based Dietary Guidelines of the World Health Organization (WHO) and European Union (EU) legislation on health claims play an important role in regulating information to the public about a wholesome diet and for improving the availability and affordability of nutritious food choices to consumers. More specifically, the food industry can contribute by reducing the number of energy-dense products; by improving the nutrient profile of processed food through the reduction of salt, added sugar, trans-fatty acid, and saturated fat content. As a result, food science and technology are prompted to create a new framework for these food-based dietary guidelines, principally in the areas of food physics, methods of food storage and preservation, nutrient restoration and fortification of foods, and the development of health-focused designer foods and functional foods. The aim of this review is to provide an overview of some further opportunities for new product development and nutrition research. Some topics related to the energy reduction of foods include: dilution and structure design, carbohydrate and/or fat substitutes, and inhibition of enzymes in carbohydrate and/or fat digestion; additionally, regulation of some metabolic functions with food-derived bioactive peptides and probiotics, and enrichment of foods with bioactive compounds are reviewed in this overview as the most promising issues.
In recent years, extensive scientific evidence has emerged indicating that dietary patterns have specific health or disease outcomes. The major causes of some specific diseases or morbidity and mortality in the world's developed and developing countries are related to poor diet and a sedentary lifestyle and eventually include obesity, cardiovascular disease, type 2 diabetes, hypertension, osteoporosis, and certain cancers (WHO/FAO 2003). At the turn of the 21st century, the industrialized world faces new challenges, that is, an enormous increase in the costs of health care, longer life expectancy, improved scientific knowledge, development of new technologies, and major changes in lifestyles. This has led to the idea of “optimal nutrition.” Nutrition scientists want to rise to these new challenges and have embraced the idea of “optimal nutrition,” which can be defined as the optimization of a daily nutrition model with nutrients and bioactive compounds to prevent diseases as well as to protect a healthy life. This approach has emerged due to increases in the costs of disease treatment, increased loss of work, and the demand by consumers for a life with higher quality standards (Ashwell 2002).
Achieving optimal nutrition through the intake of healthy foods aims at optimizing the physiological functions of each human to ensure maximum well-being. New guidelines will have to be developed concerning new foods that will become available. In this respect, food science and technology experts are creating a new framework for these food-based dietary recommendations, principally in the areas of food physics, methods of food storage and preservation, nutrient restoration, and fortification of foods, as well as the development of health-focused designer foods and functional foods (FAO/WHO 1996; USDA 2010). The WHO Regional Office for Europe has committed to supporting the implementation of the Second Action Plan by raising awareness and promoting political commitment to address food- and nutrition-related health. This plan aims to achieve some of the following health goals: to reduce the prevalence of diet-related diseases and to reverse the obesity trend in children and adolescents (WHO 2008). To achieve these health goals, population nutrition goals should be adopted in line with FAO/WHO recommendations: <10% of daily energy intake from saturated fatty acids, <1% of daily energy intake from trans fatty acids, <10% of daily energy intake from free sugars, ≥400 g fruits and vegetables a day, and <5 g a day of salt (WHO/FAO 2003).
The food industry can be a significant player in promoting wholesome diets, physical activity, and new product development in line with dietary guidelines. Initiatives have been undertaken by the food industry to reduce the levels of saturated fats, trans-fatty acids, sugars, and salt in processed foods, promote reasonable portion sizes, and increase the introduction of innovative, prudent, and nutritious choices. A review of current marketing practices could also accelerate health gains worldwide (WHO 2008).
The aim of this review is to provide an overview of further opportunities for new product development and nutrition research. In this regard, the following most promising topics have been selected: energy reduction of foods by dilution and structure design by carbohydrate and/or fat substitutes, and by the inhibition of enzymes in carbohydrate and/or fat digestion; regulating the compounds of some metabolic functions with food-derived bioactive peptides and probiotics; and the enrichment of foods with bioactive compounds.
Energy Reduction of Foods
Dietary guidelines recommend the limitation of total fat intake <30%, saturated fats <10%, and simple carbohydrates <10% of total caloric intake (WHO/FAO 2003). Calorie reduction in foods can be achieved by dilution and by decreasing the proportion of an ingested caloric nutrient with structure design; replacing the usual sweetening carbohydrate (mainly sucrose) and fat with a replacement; and adding certain substances that inhibit carbohydrate and/or lipid utilization.
Calorie reduction by structure design
Reducing the energy density of food products can be achieved by increasing the air and/or water content. This type of calorie reduction is generally applied to emulsion-type foods (such as ice cream, margarine, mayonnaise, desserts, and salad dressings) where 2 immiscible phases (water and fat) are present. The sensory properties of a product change when the amount of fat is decreased in the formulation. Through restructuring the product matrix, it is possible to overcome the sensory impacts of reduced sugar and fat quantities. The development of nutritious and acceptable food products requires specific food micro and nanoparticle structures (Rosenthal 1998; Acosta 2009; Palzer 2009). Manufacturing processes such as forming smaller bubbles or droplet sizes can modify the structure of emulsions and foams and provide increased creaminess. The nanostructuring of natural food materials can potentially enable the use of less fat but still produce flavorful food products. A typical product of this technology would be a nanostructure ice cream, mayonnaise, or spread that is low-fat but as creamy in texture as the full-fat equivalent. Such products would, therefore, offer “healthy” but flavorful products to the consumer. At the same time any microbial pathogens will be destroyed by applied micro or nanoscale processing (Chaudhry and Castle 2011). For example, ice cream is a foam made of dairy ingredients, sugar, water, and other ingredients. A liquid mix is prepared and homogenized in a rotor-stator or other high-pressure equipment to reduce the diameter of the milk fat globules below 20 μm. In this process, after agitation, air incorporation, and freezing, the ice cream mass is extruded at –18 °C in single- or twin-screw extruders. This extrusion step reduces both the number of air bubbles and ice crystal size. Thus, the product is perceived to be creamier than standard fat-reduced ice creams and the fat content can be reduced by 50% to 60% while still maintaining consumer preference attributes (Crilly and others 2008).
However, there have been considerable scientific developments in understanding the importance of the relationship between emulsion structure (droplet size, stability, interfacial architecture) and fat digestion. By altering fat digestion in a human, one hope is to decrease energy intake by enhancing the satiety responses induced by structured fats. Several studies have reported that disruption of the natural food matrix or microstructure created during processing may influence the release, transformation, and subsequent absorption of fat and carbohydrates in the digestive tract (Desai and others 1996; Prada and Aguilera 2007; Lundin and others 2008; Acosta 2009; Singh and others 2010; Golding and Wooster 2010).
Golding and Wooster (2010) reviewed the importance of the relationship between colloidal structure and digestive behaviors. In explaining how emulsion properties influence digestion behaviors, a number of points need to be considered, including the effects of droplet size and colloidal stability on fat digestion, the effects of the interface on lipid digestion, and the effects of lipid type and structure. Reducing the droplet size of fat particles has been shown to increase the rate of fat digestion, which might affect hunger because there would be a larger surface area of exposed lipid available for gastric or pancreatic lipases to attach to as the mean droplet size decreased. On the other hand, it has been suggested that the transit time of lipids in the digestive tract is sufficiently long to allow them to be completely digested irrespective of the lipid droplet size (McClements and others 2009).
Maljaars and others (2008) compared the effect of small amounts of lipid emulsions differing in droplet size and in the site of delivery on postprandial hunger, meal intake, gastric emptying half-time, and small bowel transit time. A smaller fat droplet size enhanced the ability of a given amount of fat to reduce food intake and hunger and to delay gastric emptying. The lipid droplet size, as well as the location where the lipid is digested, affects satiety. Ileal instead of duodenal fat infusion significantly reduced food intake and hunger and inhibited small bowel transit time.
Singh and others (2009) provided an important perspective on the structuring of food emulsions in the gastrointestinal tract to modify lipid digestion. They pointed out that foods with reduced fatty acid availability would be suitable for populations with high blood lipid levels and at a high risk of cardiovascular diseases and obesity. However, dietary lipids are also a source of essential fatty acids. Magnetic resonance imaging (MRI) methods provide useful information on the intragastric behavior of emulsions in relation to understanding their effects on satiety in humans. The characteristic of emulsion effect stability in the acid gastric environment seems to delay gastric emptying and increase postprandial cholecystokinin (CCK), whereas acid instability in emulsions leads to the rapid layering of fat in gastric lumen with accelerated gastric emptying and a lower release of CCK (Sing and others 2009). The interfacial structures formed from bio-surfactants such as glycolipids in processed food emulsions regulate the rate of lipolysis. Engineering or modifying the composition and phase structure at the interface affects the rate of hydrolysis. Reducing the rate of hydrolysis reduces the accumulation of the hydrolysis products at the interface. The body can sense the release of fatty acids, and this can, then, induce feelings of satiety or fullness, prompting a response to reduce fat intake (Morris 2011).
The findings of these studies indicate that quite profound differences in lipid digestion can be observed based on emulsion design. Food microstructures are useful for improving the solubility, chemical stability, and bioavailability of bioactive compounds and nutrients (Desai and others 1996; Palzer 2009). The future challenge will be to ensure our ability to investigate the factors that influence the gastrointestinal uptake of microparticles or nanoparticles to modify lipid and carbohydrate digestion and metabolism through emulsion structure.
Calorie reduction by carbohydrate and/or fat substitutes
High-calorie components (fat or sugar) can be partially replaced or substituted with one or more ingredients of low-calorie content to achieve specific effects, such as a reduction in fat or energy content. When sugar is replaced, its sweetening function is frequently provided by an intense sweetener, thus leaving the need for a bulking agent to replace the mass usually provided by sucrose or other sugars. In liquid products, such as soft drinks or sweeteners for coffee, sugar can be replaced by intense sweeteners such as acesulfame-K, aspartame, neotame, saccharin, or sucralose (Finley and Leveille 1996). Bulking agents are classified as low-molecular-weight polyols or sugar alcohols (sorbitol, mannitol, isomalt, lactitol, xylitol, erythritol, maltitol, trehalose, fructooligosaccharides, polydextrose, tagatose, and hydrogenated starch hydrolysates) and complex carbohydrate bulking agents (agarose, alginate, carrageenan, cellulose, galactomannans, D-glucans, pectin, polydextrose, xanthan gum, and resistant starch [RS]) (Rosenthal 1998; Patra and others 2009).
Among the nonnutritive sweeteners, stevioside, a sweet glycoside (300 times sweeter than sucrose) from the leaves of Stevia rebaudiana, native to Brazil and Paraguay, has drawn much attention lately (Geuns 2003; Goyal and Goyal 2010). Recently, the European Food Safety Authority (EFSA) has given the green light for the use of stevia-derived steviol glycosides in food, which will probably lead to wide-scale use in Europe (Stoyanova and others 2011). So far, little data have been available regarding the practical applications in foods and stability under different processing and storage conditions. Only one study has directly tested the effects of the natural sweetener, stevia, aspartame, or sucrose on food intake, satiety, and postprandial glucose and insulin levels in humans (Anton and others 2010). They reported no differences in food intake between the stevia and aspartame test meal days. Postprandial glucose levels were also reduced in the stevia condition compared to the aspartame and sucrose conditions at 20 min after consumption of the preload, as well as at 30 and 60 min after the test lunch meal. Postprandial insulin levels were significantly reduced in the stevia condition compared to both the aspartame and sucrose conditions.
As a part of such development, arabinoxylan oligosaccharides, which are enzymatically derived from wheat bran arabinoxylan, have most recently been shown to be a well-tolerated, nondigestible prebiotic carbohydrate for humans that, in Europe, under the definition in Commission Directive 2008/100/EC, is considered a dietary fiber. Wheat bran-extracted arabinoxylan oligosaccharides, a potential novel prebiotic, were used in sugar-snap cookies by replacing up to 30% of the initial sucrose level. Both the control cookies and cookies containing arabinoxylan oligosaccharides had comparable diameters and heights and an acceptable color and break strength. The results indicate the potential of arabinoxylan oligosaccharides as a sucrose replacer that has practical implications from a health point of view (Pareyt and others 2011).
RS can be used as an alternative-bulking agent both as a carbohydrate and a fat substitute. It has been defined as the sum of starch and its degradations products that are not absorbed in the small intestines of the healthy individuals. RS can be found naturally in the matrix of food and can also be formed during processing at home and/or in the factory (Mutungi and others 2009; Pongjanta and others 2009). For nutritional purposes, Englyst and others (1992) have classified the starch in foods as rapidly digestible starch (RDS), slowly digestible starch (SDS), and RS. There are 4 types of RS, which either occur naturally or are a consequence of food processing. Resistant starch-1 (RS1) is present in the cell walls of plants and is physically inaccessible to digestive enzymes such as α-amylase. Raw starch granules that are resistant to digestive enzymes due to their crystalline structure and size are classified as RS2. Because RS1 and RS2 occur naturally in plants, they are considered dietary fiber. RS3 and RS4 are both formed during food processing and do not occur naturally. RS3, also called retrograded starch, is formed during the cooking and cooling or extrusion process of starchy foods (Tas and El 2000). RS4 is chemically modified starch by etherization, cross binding, or esterification (Sajilata and others 2006; Fuentes-Zaragoza and others 2010).
RS has drawn considerable attention over the last 2 decades due to both its functional properties and positive impacts on health. RS or SDS can be used to replace RDSs or low-molecular weight carbohydrates in food products. Noronha and others (2007) studied the replacement of fat with RS in imitation cheese production. Based on their results, it was concluded that the replacement of fat with RS will make high-moisture cheeses firmer (according to a sensory evaluation), and it was possible to add RS up to 43.2% while maintaining acceptable functional properties. Arimi and others (2008) also concluded that the replacement of most or all of the fat in cheese with RS could be done without adversely affecting the properties of the product. The results obtained in their study show that it is possible to manufacture an imitation cheese containing RS that can be expanded on microwave-heating, presenting a novel application of imitation cheese-type matrices. The imitation cheese can be presented as a potentially wholesome snack food that contains no fat, has high protein, and contains functional fiber.
The future directions of the food industry with regard to RS is to look for alternative sources for obtaining starch with better physicochemical and functional characteristics, and as raw material for the development of RS, to study alternative methods to increase the RS content of starch and to study other health effects and technological properties, especially when it is used as a fat replacer.
Fat in foods may be partially or completely replaced by a wide range of products, classified as fat mimetics and fat substitutes. Fat mimetics are materials, usually carbohydrate- and/or protein-based, that replace the bulk, body, and mouthfeel of fats but do not replace calories on a one-to-one basis. They are not applicable to fried foods (Finley and Leveille 1996). Noncaloric (not absorbed) typical fat mimetics are locust bean, gum arabic, pectin, guar, xanthan, carrageenan, powdered cellulose, methylcellulose, and microcrytalline cellulose. Caloric fat mimetics are starch, maltodextrin, polydextrose, β-glucan. Some commercial brands of fat mimetics are Simplesse (egg protein, milk protein), Simplesse 100 (whey protein), LITA (zein), Trailblazer (white egg protein, serum protein with xanthan gum), N-Flate (nonfat milk, gums, emulsifier, and modified starch), olestra (sucrose polyester), Sorbestrin (hexa-fatty acid ester of sorbitol), EPG (esterified propoxylated glycerol esters), and TACTA (trialkoxytricarballylate) (Finley and Leveille 1996; Ognean and others 2006).
Fat substitutes are physically similar to fats and oils and can, theoretically, replace fat on a one-to-one weight basis in foods. Generally, they are macromolecules that physically and chemically resemble triglycerides (conventional fats and oils). Many fat substitutes are heat stable at cooking and frying temperatures and partially digestible. The functionality of fat substitutes ranges from oil-like to hard fat. Calorie values range from 0 to 3 kcal/g and depend on the fatty alcohols and fatty acids appended to the backbone (Rosenthal 1998; Ognean and others 2006).
Commercial examples of low-calorie fats are Caprenin® (Procter and Gamble), Olestra/Olean® (Procter and Gamble) and Salatrim® (Nabisco). They are metabolized more like carbohydrate and are rapidly used as energy rather than stored as fat. They have 2 medium-chain fatty acids and 1 long-chain fatty acid. Caprenin has 2 medium-chain fatty acids, caprylic and capric, and a 3rd, behenic acid. Salatrim is a randomized triacylglycerol containing short-chain fatty acids, acetic, propionic, and/or butyric acids and a long-chain fatty acid, stearic acid. Long-chain fatty acids are poorly digested and absorbed and, as a result, the caloric values of Caprenin and Salatrim are 5 kcal/g (Finley and Leveille 1996; Ognean and others 2006).
Olestra is a mixture of hexa-, hepta-, and octa-esters of sucrose prepared by chemical transesterification or interesterification of sucrose with 6 to 8 long-chain fatty acids isolated edible fats and oils. It is not hydrolyzed by gastric or pancreatic enzymes because of the large size and number of nonpolar fatty acids constituents. Olestra is not absorbed, and for this reason does not provide calories to the diet (Ognean and others 2006).
Likewise, certain fat substitutes have the potential to displace consumption or interfere with absorption of fat-soluble vitamins. The regular ingestion of moderate to high levels of these esters can produce an undesirable “laxative” effect namely, leakage of the ester through the anal sphincter. One way to prevent this laxative effect is to formulate the esters so that they are completely solid at body temperature This issue has been addressed by developing Olestra variations that melt above 37 °C, thus remaining solid throughout their passage through the gastrointestinal tract. In January 1996 the Food and Drug Administration (FDA) approved Olestra for use in snacks and crackers. Products containing Olestra will carry a warning about potential gastrointestinal discomfort (Allgood and others 2001; Ognean and others 2006).
The increasing demand for low-fat diets has led the food industry to develop or modify traditional food products to contain less fat. In this regard, a number of studies have been conducted to investigate the effect of replacing fat or oil to reduce fat in foods with various fat mimetics. Water-soluble pectin-enriched materials from apple pomace have been used to reduce the shortening content. When water-soluble pectin-enriched materials were incorporated into cookie formulations in place of shortening by up to 30% by weight of shortening, the cookie spread diameter was reduced and an increase in the moisture content was observed (Min and others 2010). Soluble cocoa fiber has been used as a fat replacement, reducing the fat content in chocolate muffins by replacing part of the oil ingredient. The results indicate that soluble cocoa fiber is an encouraging option for replacing oil in a chocolate muffin formulation. The main advantages were that adding soluble cocoa fiber gave the muffins greater moisture and a tenderer and more crumbly texture, as they were more fragile than the control, reduced the signs of hardening during storage, and added a fair amount of color (Martinez-Cervera and others 2011).
Low-fat mayonnaise was prepared and optimized by response surface methodology on the basis of full-fat mayonnaise, the level of egg yolk was changed, and the soybean oil was replaced with oat dextrin of different dextrose-equivalent values at the levels of 20%, 30%, and 40% of total oil. The study concluded that oat dextrin played multiple roles as a fat replacer. It can be used to produce low-fat mayonnaise, which has similar sensory properties to its full-fat counterpart but fewer calories (597.7 kcal/100 g). However, the addition of the oat dextrin adversely affected the mayonnaise texture character and taste, leading to a significantly lower sensory quality compared with the control sample (Shen and others 2011). Amorphous cellulose gel, which is obtained from cereals, is an insoluble fiber that is used as a fat substitute to reduce the level of fat in fermented sausages. The results obtained in this study indicate that amorphous cellulose gel can be used to replace up to 50% of the pork back fat content in fermented sausages. At this level of substitution, the evaluated quality attributes did not decrease, which allows the production of healthier fermented sausages due to a decrease in the fat and cholesterol levels by approximately 45% and 15%, respectively (Campagnol and others 2011).
Koca and Metin (2004) studied the effects of Simplesse100, Dairy-Lot, and Raftiline on the melting properties of low-fat fresh kashar cheese. Melting properties of fresh kashar cheese are very important because this cheese is used as an ingredient in sandwiches and pizzas in Turkey. Their results showed that the use of Raftiline caused a slight increase in meltability. The melting ability is preserved if a higher moisture level accompanies the fat reduction.
The substitution of animal fat or oil with ingredients that have similar technological functions and retain the sensory characteristics of foods is a promising alternative to produce healthier products. Therefore, there is great interest in developing new food products containing β-glucan hydrocolloids, inulin, and rice bran fiber as fat substitutes for use in low-fat foods (Piñero and others 2008; Lee and others 2009; Bayarri and others 2010; Choi and others 2010; Arcia and others 2011).
Calorie reduction by the inhibition of enzymes in carbohydrate and/or fat digestion
Inhibiting the digestion and absorption of dietary lipids and carbohydrates provides a successful approach in weight management. In the continuing search for novel anti-obesity agents, numerous plant-derived phytochemicals have been screened for potential lipase inhibition activity (Slanc and others 2009; Tucci and others 2010), α-amylase and α-glucosidase inhibition activity (Apostolidis and Lee 2010; Gunawan-Puteri and Kawabata 2010; Koh and others 2010; Wang and others 2010; Gonçalves and others 2011), and both antilipase and anti-amylase activity (Ikarashi and others 2010). Recently, Tucci and others (2010) reported that certain saponins, polyphenols, and terpenes are able to inhibit digestive enzymes. One example of these is saponins, which are glycosides known for their soap-like foaming ability when mixed with water. This foaming ability results from the combination of a lipophylic sapogenin and a hydrophilic sugar part. Certain saponins, such as oleanane, lupine, and dammarane-types, can inhibit pancreatic lipase activity and, therefore, have potential as treatments that could prove effective for obesity and related disorders.
Acanthopanax senticosus, also known as Siberian ginseng or Eleutherococcus senticosus, is a shrub commonly found in northeastern Asia. Acanthopanax sessiliflorus sessiloside and chiisanoside are lupine-type saponins found in the leaves of A. sessiliflorus. Aesculus turbinata escins (Japanese horse chestnut) is a medicinal plant widely distributed in northwestern China. These plants all exhibit pancreatic lipase inhibitory activities in vitro (Yoshizumi and others 2006). Also, the tea plant Camellia sinensis has shown that, in mice, it accelerates GI transit and exerts an inhibitory effect on pancreatic lipase with an IC50 of 0.091 mg/mL. Dioscorea nipponica is a herb that grows in the mountainous areas of the Korean peninsula. The extract of D. nipponica appears to inhibit porcine pancreatic lipase activity with IC50 values of 5 to 10 mg/mL.
Three types of tea—green, oolong, and black—are used around the world as traditional beverages. Green and oolong tea have been reported to exert anti-obesity and hypolipidemic actions. Black tea also contains many active ingredients; however, some may not survive processing. These teas contain several different active ingredients that may exert -obesity actions through various mechanisms. Oolong tea contains 2 saponins (theasaponins E1 and E2) that seem to competitively inhibit pancreatic lipase activity with Km and Vmax values of 1.42 mg/mL and 476.2 nkat/L, respectively (Tucci and others 2010). However, no data and no studies of the clinical potential of these saponins have been reported.
Apple polyphenols and the procyanidin fractions extracted from apple polyphenols inhibited pancreatic lipase activity and significantly decreased plasma triglycerides after corn oil loading. Also, researchers reported no side effects after the administration of apple phenols as 600-mg capsules (Sugiyama and others 2007). The polyphenols of grape seed extracts (Ardevol and others 2000) and terpenes include carnosic acid and carnosol, which can be extracted from the leaves of sage (Tucci and others 2010); crocin and crocetin, which are found in Gardenia fructus (Lee and others 2005), exert inhibitory activity on pancreatic lipase. They are all new potential compounds. In vitro studies have shown that extracts of black, green, and mulberry teas, berry polyphenols, and oolong tea catechins could interfere with carbohydrate and triglyceride absorption due to their ability to inhibit α-amylase, α- glucosidase, sodium-glucose transporters, and pancreatic lipase (McDougall and Stewart 2005). According to Ikarashi and others (2010), acacia polyphenol extracted from the bark of the black wattle tree significantly inhibited a rise in plasma glucose concentration after maltose and sucrose loading. Researchers found a similar inhibitory effect in plasma triglyceride concentration after olive oil loading. Other potential inhibitors include an aqueous extract of peanut cotyledons and peanut shell that have shown inhibitory activity toward pancreatic and human salivary α-amylase and lipases (Tucci and others 2010). However, there are no consistent or complete data relating to the mechanism of action and benefits for weight control.
Phytic acid is an antinutritional component in foods, but it is of prime concern in human nutrition and health management. The chemical description of phytic acid is myoinositol (1,2,3,4,5,6)-hexakisphosphoric acid. The unique structure of phytic acid offers it the ability to strongly chelate with cations such as calcium, magnesium, zinc, copper, iron, and potassium to form insoluble salts. Therefore, it adversely affects the absorption and digestion of these minerals, as seen in animals (Oatway and others 2001). The salts of phytic acid are designated as phytates (myo-inositol-1,2,3,4,5,6-hexakisphosphates) that are mostly present as salts of the mono- and divalent cations K+, Mg2+, and Ca2+.
Paradoxically, phytate may have some benefits in human nutrition, particularly in relation to carcinogenesis, as it has been shown to have protective effects against colon cancer. The complexion of Fe by phytate may reduce the Fe-catalyzed production of free radicals in the colon. In pigs, it has been shown that phytate derived from maize and soybean meal was protective against lipid peroxidation in the colon associated with Fe. High-fiber diets contain substantial phytate concentrations, and this factor may partially explain the epidemiological association of high-fiber diets with lower incidences of certain cancers (Konietzny and Grenier 2003).
Phytates are negatively charged over a wide pH range, so they have an affinity for positively charged molecules and form stable complexes with proteins, carbohydrates, and lipids. This interaction lowers the solubility, functionality, digestibility, and bioavailability of these food components. The interaction of phytate with a lipid forms a lipophytin complex. Lipid and Ca phytate may be involved in the formation of metallic soaps in the gut lumen. This fact can be used to decrease the energy coming from lipids and, consequently, may also lower the risk of cholesterol formation (Vohra and Satyanarayana 2003). Young chicks, when fed diets supplemented with fat and phytate, exhibit hampered phytate-P utilization, and a large percentage of fat is excreted as soap fatty acids (Kumar and others 2010). Phytate may be used to control carbohydrate digestibility and glucose response (glycemic index). The interaction of phytate with carbohydrates has 2 different mechanisms. One of them is the formation of phytate carbohydrate complexes that make carbohydrates less degradable and thereby adversely affect the digestibility and absorption of glucose. The other one is the inhibition of amylase activity by complexing with Ca++ ions and decreasing carbohydrate degradation (Selle and others 2000). In vitro studies have shown that the incubation of human saliva with either wheat or bean starch incorporated with Na phytate reduced the phytilin-mediated hydrolysis of starch (Kumar and others 2010).
Lectin is another substance that has found popularity in the last few decades. Lectins are carbohydrate-binding proteins or glycoproteins. In addition, they act as storage and/or defense proteins when a plant or seed is assaulted by insects or fungi. Some mushroom lectins have exhibited various biological activities, such as antitumor, immunomodularity, antiproliferative, and HIV-1 reverse transcriptase-inhibiting activities, and can be utilized as therapeutic agents for preventing or controlling obesity. The potential use of pulse lectins as a nutraceutical for controlling obesity can be attributed to their ability to resist gastric digestion and by their ability to be absorbed into the bloodstream while remaining biologically active (Roy and others 2010; Yan and others 2010; Zhang and others 2010).
Recently, the inhibitory effects of the some peptides derived from the egg white protein hydrolysate against the α-glucosidase and α-amylase have been demonstrated under in vitro conditions. The result suggested that the bioactive peptides from the egg white protein that exhibited the α-glucosidase inhibitory activity (AGI) could be considered a potential AGI agent. In particular, α-glucosidase inhibitory activities of some peptides were comparable to that of the therapeutic AGI drug acarbose (IC50 60.8 μmol/L). They could be potential candidates in developing medicinal AGIs. Nevertheless, further studies in terms of the antidiabetic activity in vivo and the binding mechanisms between the peptides and active site of the enzyme are necessary (Yu and others 2011).
Regulating Compounds of Some Metabolic Functions
Food-derived bioactive peptides
The potential for bioactive peptides to contribute to better nutrition through ingestion with functional foods has been widely discussed in the scientific community. Many peptides of plant and animal origin with relevant potential regulatory functions in the human system have been discovered, with by far the most being isolated from milk-based products, eggs, meat, fish, and other marine organisms, as well as from different protein sources such as soy, wheat, broccoli, and rice (Hartmann and Meisel 2007; Kim and Wijesekara 2010).
Bioactive peptides are inactive in the sequences of their parent protein, but they can be released and become active during food processing and/or gastrointestinal digestion by enzymatic hydrolysis. Moreover, bioactive peptides usually contain 3 to 20 amino acid residues, and their activities are based on their amino acid composition and sequence (Korhonen and Pihlanto 2003; de Llano and Sánchez 2003; Phelan and others 2009).
Chemical and biological methods have been developed and applied to screen for bioactive peptides that could promote different health effects; however, only some of the postulated health effects have been demonstrated in human studies (Hartmann and Meisel 2007). Depending on the amino acid sequence, bioactive peptides may act as a regulatory component in various biological functions in the body, such as antimicrobial activities; antioxidant, antithrombotic, antihypertension, immunomodulatory, or opioid agonist or antagonist activities; anticancer activities; and mineral binding, in addition to nutrient utilization (Korhonen and Pihlanto 2006; Hartmann and Miesel 2007; Phelan and others 2009).
Opioid peptides are peptides that have an affinity for an opioid receptor. All have the same N-terminal sequence (Tyr-Gly-Gly-Phe). These peptides exert their activity by binding to specific receptors of the target cell, such as the μ-receptor for emotional behavior and suppression of intestinal motility, κ-receptor for food intake and sedation, and σ-receptor for emotional behavior. The first food-derived opioid peptides are β-casomorphins. Casoxins, lactorphins, and exorphins are the other opioid peptides (Pihlanto-Leppälä 2001).
Angiotension I-converting enzyme (EC 184.108.40.206; ACE) plays a crucial role in the regulation of blood pressure. High blood pressure is one of the major independent risk factors for cardiovascular disease. ACE promotes the conversion of angiotensin-I to the potent vasoconstrictor angiotensin II while inactivating the vasodilator bradykinin and stimulating the release of aldosteron in the adrenal cortex, which has a tendency to increase blood pressure (Pihlanto-Leppälä 2001; Möller and others 2008; Kim and Wijesekara 2010).
Glycomacropeptide (GMP) or caseinomacropeptide (CMP) is another bioactive peptide formed during the manufacturing of cheese by the chymosin (or pepsin) cleavage of κ-casein between Phe105 and Met106. It is the most abundant peptide in whey proteins. According to the literature, CMP is related to the modulation of immune system responses and promotes bifidobacterial growth due to its carbohydrate content (mainly sialic acid) (Phelan and others 2009). CMP has been reported to help appetite control and weight management by inhibiting gastric secretions, slowing down stomach contractions, and stimulating the release of satiety hormone (CCK). Caseinophosphopeptide (CPP) has been reported to bind and solubilize minerals and, thus, can be used to prevent osteoporosis, dental caries, anemia, and hypertension (Manso and Lopez-Fandino 2004; Korhonen and Pihlanto 2006; Thoma-Worringer and others 2006, Phelan and others 2009).
Bioactive peptides can be liberated mainly in 3 different ways: in vivo during digestion by digestive enzymes, in vivo during digestion by microbial enzymes of the intestinal flora, and in vitro during food processing or ripening by exogenous or endogenous or microbial enzymes. In many studies, combinations of these 3 methods have proven effective in the generation of bioactive peptides (Yamamoto and others 1994; Fuglsang and others 2003; Korhonen and Pihlanto 2003).
Many types of bioactive peptides have been identified in milk protein hydrolysates and fermented dairy products. Many industrially utilized dairy starter cultures are highly proteolytic. Bioactive peptides can be generated by starter and nonstarter lactic acid bacteria (LAB), for example, Lactococcus lactis, Lactobacillus helveticus, and Lactobacillus delbrueckii ssp. bulgaricus in the manufacturing of fermented dairy products (Korhonen and Pihlanto 2003; Silva and Malcata 2005; Korhonen 2009). However, alternative sources have been investigated; one of them is marine organism, which is a rich source of structurally diverse bioactive compounds (Kim and Wijesekara 2010). Soybeans are also rich in proteins (40% to 50%). Several studies have shown that the peptide content of soy-fermented products is greater than that of unfermented soybeans (Gibbs and others 2004). Other legumes (for example, common dry beans, dry pinto beans, lentils, and chickpeas) are also sources of bioactive peptides, especially with ACE inhibitory activity (Akıllıoğlu and Karakaya 2009; Roy and others 2010).
Calpis (a sour milk product), Evolus (a calcium-enriched fermented milk drink), and BioZate (hydrolyzed whey protein) are commercial products that have been claimed to reduce blood pressure based on bioactive peptides. Capolac is an ingredient that purports to “help mineral absorption.” PRODIET F200/Lactium is a flavored milk drink purporting to reduce stress effects (Korhonen and Pihlanto 2006; Korhonen 2009).
The future directions of the food industry with respect to bioactive peptides will include investigating alternative protein sources and researching other possible health effects on such topics as type II diabetes and cognitive performance. Among the novel production technologies that concentrate protein hydrolysates, such as chromatographic and membrane separation techniques, recombinant enzyme technology and specific production strains or peptidases isolated from suitable microorganisms are likely to be employed industrially in the future.
Probiotics are defined as the “living microorganisms (bacteria or yeasts), which when ingested or locally applied in sufficient numbers confer one or more specified demonstrated health benefits for the host” (FAO/WHO 2001). Probiotics have beneficial effects such as stimulation of the growth of preferred microorganisms, crowding out potentially harmful bacteria, and reinforcing the body's natural defense mechanisms (Dunne 2001).
In the food industry, a significant problem is the viability of probiotic bacteria, as they are affected by gastrointestinal conditions that make it difficult for them to survive and to multiply normally. Cell survival is particularly affected by certain food matrix conditions such as elevated water activity (aw > 0.25), ideal storage temperature, and the presence of atmospheric oxygen. Current research studies on novel probiotic formulations are based on forming a barrier system against adverse external conditions by microencapsulation technology for lengthening the life of probiotic bacteria in functional foods that contain them.
Microencapsulation is a technology of packaging solids, liquids, or gases in small capsules that can release their content under specific conditions. This technique has been widely used for the delivery of bioactive components such as antioxidants, vitamins, and minerals. In recent years, it has also been used for the stabilization of probiotic cells (Champagne and Fustier 2007; Heidebach and others 2009, 2010; Weinbreck and others 2010). Different encapsulation studies have been conducted with applications of several materials (alginate, casein, carrageenan, chitosan, and starch) and various techniques (spray-drying, freeze-drying, spray-concealing, fluidized-bed-coating, extrusion, coacervation/phase separation technique, nanoparticles, emulsion formation, cocrystallization, and electrostatic methods) (Anal and Singh 2007; Annan and others 2008; Heidebach and others 2009, 2010; Fang and Bhandari 2010). A number of studies have reported that the best matrices to deliver probiotics are fermented milk products, and traditionally, probiotics have been added to yogurt. However, there is increasing consumer demand for probiotic products in nondairy foods, mainly sought by vegetarians, cholesterol controllers, and lactose-intolerant individuals. For this purpose, probiotic microorganisms are incorporated into mayonnaise, soy milk, meat products, baby foods, ice cream, fruit drinks, and vegetables, and they are given as supplements in such forms as capsules, tablets, or freeze-dried preparations (Homayouni and others 2008; Prado and others 2008; Granato and others 2010; Rivera-Espinoza and Gallardo-Navarro 2010; Rößle and others 2010).
Fermented functional foods are known for either their probiotic effect (directly due to the direct interaction of the living organism with the host) or their biogenic effect (indirectly as a result of the ingestion of microbial metabolites produced during the fermentation process). Several studies have shown that nonviable probiotics can also have beneficial effects, and this approach can be explained by the production of secondary metabolites (such as B vitamins, bioactive peptides, exopolysaccharides, bacteriocins, and organic acids) during fermentation, mainly by LAB. These soluble metabolites present in the whole nonbacterial fraction can be easily spray-dried and added as dried powder to food matrixes. The use of these cells instead of viable ones has certain advantages: longer shelf-life, easier storage, handling, and transportation, as well as reduced requirements for refrigerated storage. This approach can be an alternative, especially for developing countries where strict storage conditions cannot be met. Also, this approach allows the functional effects of probiotics to be offered in nondairy food products such as cereals, chocolate products, honey, biscuits, dressings, cakes, sweeteners, tea, and chewing gum (Vinderola 2008).
Enrichment of Foods with Bioactive Compounds
As defined by Kitts (1994), bioactive compounds are “extranutritional” constituents that typically occur naturally in small quantities in plants and lipid-rich foods (Kris-Etherson and others 2002). Impressive progress is being made in defining the role of bioactive compounds for reducing the risk of major chronic diseases and the underlying biological mechanisms that account for these effects. The biological effects and food sources of these compounds are summarized in Table 1.
Table 1–. Potential health benefits of some bioactive compounds.
|Coenzyme Q 10||Beef steak, chicken, soybean oil, canola oil, peanuts, sesame seeds, pistachio, broccoli||Antioxidant, anti-aging, ↓CVD risk, ↓BP, ↓neurodegenerative disease risk, ↑athletic performance, ↓cancer risk||Langsjoen and Langsjoen (1999); Turunen and others (2004); Ercan and El (2010)|
|L-Carnitine||Beef steak, pork, milk (whole), fish (cod), chicken breast, beef liver, beef heart||Antioxidant, anti-aging, ↓CVD and Alzheimer's disease risks; ↑physical performance, ↑sperm motility||Rebouche (2004); Harpaz (2005); Kurt and El (2010)|
|Alpha-Lipoic acid||Kidney, heart, liver, spinach, broccoli, tomatoes, Brussels sprouts||Antioxidant, ↓diabetes mellitus risk, regeneration of other anti-oxidants||Smith and others (2004); Kramer and Packer (2001)|
|Lignan||Flaxseeds, sesame seeds, curly kale, broccoli, apricots, cabbage, Brussels sprouts, tofu, strawberries||Estrogen/anti-estrogen, ↓CVD, hormone-associated cancers and osteoporosis risks||Lampe (2003); Patade and others (2008)|
|Isothiocyanates||Brussels sprouts, garden cress, mustard greens, turnip, cabbage Savoy, kale, watercress, cabbage red, broccoli horseradish, cauliflower||Tumor initiation/promotion, carcinogen activation, carcinogen detoxification||Kris-Etherton and others (2002); Vig and others (2009)|
|Curcumin||Turmeric is a spice derived from the rhizomes of Curcuma longa, a member of the ginger family. Curcumin is the principal curcuminoid in turmeric||Antioxidant, anti-inflammatory activity, carcinogen detoxification, inhibition of tumor invasion||Surh and Chun (2007); Maheshwari and others (2006)|
|Isoflavone||Soy protein concentrate, miso, tempeh, soy milk, tofu yogurt, tofu soy cheese, soy meat.||↓CVD, LDL-C, hormone-associated cancers and osteoporosis risks||Dewell and others (2006)|
|Resveratrol||Red grape, wine, grape juice, peanuts, berries of Vaccinum species, including blueberries, bilberries, and cranberries||↓LDL-C oxidation, platelet aggregation, and CVD risks; anti-oxidant, carcinogen detoxification, antimutagen, ↓tumor initiation/promotion, estrogen/anti-estrogen||Kris-Etherton and others (2002); Saiko and others (2008)|
|Chlorophylls||Spinach, parsley, green beans, cress, leeks, endive sugar peas||Antioxidant, carcinogen detoxification, ↓aflatoxin-associated liver cancer risk||Kamat and others (2000); Kumar and others (2001)|
|Lycopene||Tomato, watermelon, apricot, grapefruit||Antioxidant, ↓CVD risk, improve endothelial function, ↓ some cancers such as prostate and breast||Wang and Leung (2010); Kim and others (2011)|
|β-glucan||Cell wall of fungi, yeast, bacteria, oat, barley||Stimulation of immune system against infections, modulation of humoral and cell immune system, stimulation of hematopoiesis, stimulation of macrophages, protective effect on DNA damage, controlling blood sugar, ↓ TC||Pick and others (1996); Volman and others (2008); Anglei and others (2009)|
|Sterol and stanol||Wheat germ, wheat bran sesame oil, almonds, Brussels sprouts, corn oil, canola oil, peanuts, rye bread, macadamia nuts, olive oil||↓ TC, LDL-C, and some cancers, improve artherial health, anti-inflammatory activity, anti-oxidant activity||Ostlund (2002); Berger and others (2004); Woyengo and others (2009); Rudkowska (2010)|
|Inulin||Asparagus, garlic, chicory, leek, onion, and artichoke||Prebiotic effect, enhances gastrointestinal mineral absorption, ↓ atherosclerosis, ↑ satiety||Liu (2007); Azorin-Ortuno and others (2009)|
|Omega-3 fatty acids||Fish (cold water oily fishes, especially salmon, herring, macherel, sardines), flax seed, walnut||Anti-inflammatory, ↓ TG, LDL-C, platelet aggregation, anti-arrythmic effects, blood pressure, hearth rate, plaque stabilization, ↓ CVD risk, insulin resistance, protective against dementia and Alzheimer's disease, ↓ risk of depression||Ruxton and others (2004); Harris and others (2008)|
Healthy individuals, in addition to consuming them in the diet, can synthesize conditionally essential component in bioactive compounds in adequate amounts, but they may be required in the diet under conditions of illness. Aging and chronic diseases may also increase the need for the dietary intake of these conditionally essential compounds. In past decades, enrichment has been applied for the replacement of nutrients lost during the processing of foods. However, today, enrichment is applied to provide desired functionality through the addition of health-promoting ingredients (Senorans and others 2003).
Bioactive compounds have different characteristics, such as molecular structure, molecular weight (low to high), polarity (nonpolar, polar, amphiphilic), and physical state (solid, liquid, gas). Therefore, they are often incorporated into some form of delivery system instead of added directly in their pure form. At the moment, the delivery system has a vital role in preventing and/or increasing the bioavailability of an added bioactive compound. Thus, a delivery system must have different properties, such as protection of the functional ingredient from biological or chemical degradation that may occur during processing, storage, and consumption (oxidation, hydrolysis); control of the release of the functional ingredient at the target site of the body (pH, ionic strength, temperature); and compatibility of the bioactive compound with the other components and physicochemical properties of the food such as texture, appearance, and taste (Ubbink and Krüger 2006; Weiss and others 2006).
Under these circumstances, a wide range of delivery systems has been developed to encapsulate bioactive compounds such as simple solutions, emulsions, and microencapsulations. However, the future trend in these types of delivery systems is the application of nanotechnology. The novel applications of nanotechnology that are primarily used in the food industry include the use of nanoparticles such as micelles, liposomes, nanoemulsions, and nanolaminates (McClements and others 2007; Moraru and others 2009).
Micelles are 5 to 100 nm dia spherical particles applied to encapsulate water-insoluble compounds, such as some vitamins, lipids, antimicrobials, and antioxidants, and make them soluble in water. The obtained micelle is generally called a microemulsion. Microemulsions have been applied for the encapsulation of various food components such as lycopene, lutein, omega-3 fatty acids. Also, some patented applications involve, for example, the encapsulation of alpha-tocopherol in fish oil and some essential oils in carbonated beverages (Chen and others 2006).
Liposomes are particles ranging from 20 nm to 100 mm. In contrast to micelles, they can be used to encapsulate both water- and lipid-soluble components. Depending on the preparation method, they can be uni- or multilamellar, containing one or many bilayer shells, respectively. Vitamin C lost all of its activity after 19 d, whereas liposome-encapsulated vitamin C retained 50% of its activity after 50 d of refrigerated storage (Taylor and others 2005; Weiss and others 2006).
Nanoemulsion is a mixture of 2 completely or partially immiscible liquids (for example, oil and water) such that one of them is dispersed in the other in the form of spherical droplets. They can be classified according to their layer configuration; an emulsion in which oil droplets are dispersed in an aqueous phase is called an oil-in-water (O/W) emulsion, whereas a system that consists of water droplets dispersed in oil is called a water-in-oil (W/O) emulsion. In addition to these types of emulsions, other types of multiple emulsions include oil-in-water-in-oil (O/W/O) or water-in-oil-in-water (W/O/W). Thus, they can be used to deliver 2 or more functional components in a single system due to a specific response (McClements and others 2007).
McClements and others (2007) reviewed the application of O/W emulsions used for the encapsulation of ω-3 fatty acids and their incorporation into various food products such as yogurt, ice cream, and milk. They have also been used to incorporate other functional ingredients such as lycopene, lutein, β-carotene, plant sterols, and conjugated linoleic acids.
Another type of these emulsions is a multilayer emulsion that consists of oil droplets (the core) surrounded by nanometer-thick layers (the shell) comprised of different polyelectrolytes. In this system, the bioactive compound is trapped within the core of a multilayer emulsion. The application of such a system can increase bioavailability by encapsulating and protecting the bioactive compound during storage and then allowing it to be broken down in the gastrointestinal system, where the bioactive compound is released and absorbed by a targeted release of the bioactive compound due to the design of the integrity or permeability of the nanolaminated coating to respond to specific biological properties (such as pH, ionic strength, or enzymes) to release the compound to a specific site where it is most effective, such as the mouth, stomach, small intestine, large intestine, or colon (McClements 2010).
Nanolaminates consist of 2 or more layers of materials physically or chemically bound to each other with nanometer dimensions. Proteins, lipids, and polysaccharides can be used to make film. These types of nanolaminates can be applied in the preparation of edible coatings and films on food surfaces to serve as a barrier (such as a moisture barrier), to improve the textural properties of food, and/or as a carrier for a bioactive compound. Edible coatings and films are currently used with different foods such as vegetables, fruits, candies, chocolate, and meats (Weiss and others 2006; Sekhon 2010).
Currently, there are several food ingredients and products in the area of nanofood. Some examples of these types of products are Novasol® from Aquanova® (Germany) (a nanomicelle-based carrier system to introduce antioxidants into beverages and foods), Canola Active Oil (Shemen Industries, Israel) (providing increased penetration of vitamins, minerals, and phytochemicals through the use of a nanomicelle carrier), Tip Top-up bread (George Weston Foods, Australia) (containing microencapsulated tuna fish oil), Nanotea (Shenzhen Become Industry & Trade Co. Ltd., China) (selenium-rich tea), and BioDelivery Sciences International (BDSI) Bioral™ nanochelate (a nutrient delivery system) (Chudhry and others 2007; Sekhon 2010).
Today's food industry goal is to develop innovative solutions that address nutrition challenges. Experts proclaim daily that the only hope for business survival is the ability to continue innovating. In the past, the criteria for screening a new product idea have tended to be marketing factors. The manufacturer must not only know the technology of combining ingredients to produce an attractive, palatable, and safe food, but also, in the current regulatory climate, give serious consideration to the formulation of the existing and recommended dietary guidelines. In this regard, it is apparent that changes that influence the development of healthy products will come thick and fast in the next few years.
Food manufacturers have the responsibility to supply the widest range of products in accordance with the principles of dietary guidelines. The food industry can contribute by improving the availability of healthy food choices, specifically by reducing the availability of energy-dense products; by improving the nutrient profile of food through reductions in the salt, sugar, total fat, and saturated fat content; and by increasing the content of bioactive compounds.