to heat, pH, shear and salt (Nielsen 1996). There is more than one form available commercially: Slendid®100 and 110 are LM pectins, while Slendid®200 is HM pectin. Slendid® line of products can replace up to 100 per cent of the fat in a wide range of food products including mayonnaise, salad dressings, processed meats, ice cream, processed cheeses, soups and sauces, desserts, and bakery products (Artz and Hansen 1994). The use of Slendid® can reduce the fat content in mayonnaise from 80 per cent to 3 per cent, and in a frankfurter from 25±35 to 3±5 per cent (Nielsen 1996).
Oatrim is a fat replacer developed and patented by the US Department of Agriculture (USDA) in 1991. Oatrim is produced from the partial hydrolysis of oat flour or bran by a-amylase with the 0-glucan contents of 1±10 per cent (Cho and Prosky 1999). Oatrim is a soluble, tasteless powder that can be incorporated into food as a dry powder (4 kcal/g) or as a gel (1 kcal/g). Oatrim is heat stable for baking and can withstand pasteurization processing conditions, but is not suitable for frying (Calorie Control Council, 1996; Van der Slvijs et al. 1999). Oatrim or its gel gives the sensory property of natural taste and fatty texture to foods. Oatrim applications include pasteurized cheeses, dairy products, confectionery, frozen desserts, cereals, baked goods, and meat products (Inglett 2001). ,3-Glucan components in the oatrim have been reported to have a serum cholesterol-lowering effect (Inglett 1997, 2001). Oatrim is licensed for commercialization to ConAgra (Omaha, NE), Quaker (Chicago, IL) and Rhone-Poulenc (Cranbury, NJ).
Z-trim was also developed by the USDA. It is made from the high-cellulose portion of the hulls of oats, corn, rice, soybean, and peas, or bran from corn or wheat (Bollinger 1995; Akoh 1998), and is a tasteless, insoluble and indigestible fiber with zero calories. Z-trim gel contributes fiber, moistness, large water-holding capacity, high viscosity, and smooth texture. These properties make it possible for the reduced fat foods to taste like the traditional foods that are rich in fat. Z-trim has food applications in reduced-calorie cheeses, hamburgers and baked goods, but it is not suitable for deep fat frying (Cho and Prosky 1999).
Polydextrose was invented at Pfizer Inc. in the mid-1970s (Rennhard 1975). Polydextrose has been used primarily as a low-calorie bulking agent, but it is also used as a fat replacer. Polydextrose is made up from randomly cross-linked D-glucose polymers containing a small amount of sorbitol and citric acid (LaBarge 1988). Polydextrose has reducing carbonyl groups that participate in the Maillard browning reaction. It is only partially hydrolyzed by digestive enzymes (Dziezak 1986; Mitchell 1996) and contributes 1 kcal/g, which is quite attractive to health-conscious individuals. However, a laxative effect may be observed from excessive consumption of 90 g/day because a large proportion of polydextrose is excreted intact (Artz and Hansen 1994). Products with more than 15 g of polydextrose per serving must be labeled. Polydextrose is available as a powder with a pH of 2.5±3.5 and a 70 per cent solution with a pH of 5.0±6.0 (Dziezak 1986). Polydextrose is odorless, nonsweet, and highly soluble in water. It exhibits high viscosity when dissolved in water, resulting in creaminess and mouthfeel similar to fat (Dziezak 1986). Polydextrose is commonly used in several food categories, including frozen dairy desserts, baked goods, chewing gums, frostings, salad dressings, puddings, hard and soft candies, spreads, sweet sauces, and syrups (Artz and Hansen 1994). Litesse® is a polydextrose-type product manufactured from Pfizer, Inc. (Mahungu et al. 2002) and may be used as a fat replacer, bulking agent and humectant.
Gums, also often referred to as hydrocolloids, are high molecular weight carbohydrates that have traditionally been used as thickeners, stabilizers, and viscosity enhancers at very low concentrations of 0.1±0.5 per cent to form gels. The type of gum used for a particular food application depends on pH, temperature, and concentration, which can affect viscosity and gel-forming characteristics (Lucca and Tepper 1994). Gums are not used directly as fat replacers, but they are used in formulating low-fat products because they mimic the sensory property of fat such as a slippery and creamy mouthfeel. Agar, alginate, gum arabic, carrageenan, guar gum, locust bean gum, and xanthan gum are frequently used in salad dressings, icings and glazes, desserts, ice cream, dairy products, ground beef, baked goods, soups, and sauces.
Galactomannan gum is most widely used in food products and guar gum and locust bean gum belong to this type. Guar gum is obtained from the seeds of an annual leguminous plant (Cyamopsis tetragonolobus). The locust bean gum, also known as carob galactomann, is the common name for the seeds of the carob tree (Ceratonica siliqua) and has been used as a food source for thousands of years, whereas guar gum was developed and launched recently to the market owing to a lack of locust bean gum (Clegg 1996). Both gums are neutral polysaccharides composed of a linear chain of a-1,4 linked Q-D-mannose to which single a-Dgalactose units are attached via a-1,6 linkages (Clegg 1996; Lazaridou et al. 2000). Guar gum and locust bean gum are different in their ratio of mannose to galactose (M:G ratio) and the position of the galactose side chains on the main chain backbone.
Guar gum has a highly substituted structure with an M:G ratio of about 1.8±2.0, whereas locust bean gum has an M:G ratio about 3.5±4.0 (Schorsch et al. 1997). Guar gum is soluble in cold water and produces highly viscous, pseudoplastic solutions (Clegg 1996; Herald 1986). In contrast, locust bean gum is not easily soluble in cold water and needs heating (80ëC) for complete hydration to give a highly viscous solution. Locust bean gum gel is not affected by pH change or ionic strength. Galactomannan is not directly used as a fat replacer and the main function of galactomannan gums in low-fat foods is that they control viscosity by holding water (Setser and Racette 1992). This becomes important as the fat level in foods is reduced. Guar gum and locust bean gum have many food applications, including ice cream, frozen desserts, low-fat cheese products, bakery goods, sauces, and dressings. Locust bean gum is preferred in frozen desserts because it retards ice crystal growth. Guar and locust bean gum have a synergistic effect with xanthan gums.
Xanthan gum was discovered about 50 years ago and is produced by fermentation of bacterium Xanthomonas campestris. The main polymer chain consists of 3-1,4 linked D-glucose units identical to that of cellulose but substituted on every second residue with a charged trisaccharide group. This side group consists of two mannose units separated by a glucuronic acid residue (Clegg 1996; Schorsch et al. 1997). Xanthan gum is readily soluble in cold or hot water and exhibits a highly viscous, pseudoplastic rheology. Like galactomannan gums, xanthan gum does not serve as a direct fat replacer, but can be used as a stabilizer in low-fat foods by controlling viscosity and texture. Xanthan gum is stable over a wide range of pH and temperature, whereas other gums lose their viscosity under the same conditions. Such properties persist even at very low concentrations (0.1 per cent) and functions as a very effective stabilizer in low-fat foods such as dressings, sauces and mayonnaises to exploit its weak-gel (Clegg 1996). Kelco (Clark, NJ) has a line of products made from xanthan gum such as Keltrol, Keltrol BT, Keltrol GM, and Keltrol SF.
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