Lipid-based fat replacers are a stable group and include the synthetic compounds. They have chemical structures similar to triacylglycerols, but have reduced or zero caloric content because they are not fully hydrolyzed by digestive enzymes. Examples for lipid-based replacers are sucrose polyester (olestra), sucrose fatty acid esters, structured lipids, caprenin, salatrim, medium chain triacylglycerols, dialkyl dihexadecylmalonate (DDM), esterified propoxylated glycerol (EPG), and trialkoxytricarballylate (TATCA).
Sucrose polyesters or SPE, commonly known as olestra (Olean, Procter & Gamble Co., Cincinnati, OIT), is the common name for the mixture of sucrose esters with the addition of six, seven or eight fatty acids. The common fatty acids are C16:0, C18:0, C18:1, C18:2, and C18:3 fatty acids (Rizzi and Taylor 1978; Akoh 2002). Sucrose polyesters are prepared from the reaction of fatty acids with the hydroxyl groups of sucrose in the presence of catalysts (Gardner and Sanders 1990). The types of fatty acids determine the physicochemical properties of olestra (Akoh 2002) and can be formulated for a variety of foods such as fried foods, cooking oils, shortenings, baked goods and spreads (Giese 1996b; Dziezak 1989). Olestra prepared from saturated fatty acids is solid, whereas olestra prepared from unsaturated fatty acids is liquid at room temperature (Peters et al. 1997). Olestra is non-caloric because the molecule is too large to be absorbed or metabolized by pancreatic lipase (Mattson and Nolen 1972; Grossman et al. 1994). It has the organoleptic and thermal properties of fat. For this reason, it can be used in high-heat applications such as baking and frying. Olestra was approved by the FDA in 1996 as a food additive. It can be used as a replacement for up to 100 per cent of the fats and oils used in the preparation of savory snacks such as potato, tortilla and corn chips, crisps and crackers (Prince and Welschenbach 1998; Warshaw and Franz 1996).
Olestra passes through the gastrointestinal tract without being absorbed and it may be associated with cramping, loose stools and reduced absorption of fat-soluble vitamins and nutrients. Therefore, use of olestra in foods requires the addition of specific amounts of vitamins A, D, E, and K to these foods. Research has shown that olestra does not significantly interfere with the absorption of macronutrients such as carbohydrates, proteins, or water-soluble vitamins and minerals (Bergholz 1992). Olestra is a lipophilic compound and its impact on the absorption and efficacy of lipophilic drugs such as oral contraceptives, diazepam and propranolol was investigated. Results indicate that there was little possibility of interfering with the absorption or bioavailability of lipophilic drugs (Miller et al. 1990, Prince and Welschenbach 1998). Toxicologic feeding studies in animals concluded that olestra is not toxic, carcinogenic, mutagenic, or teratogenic (Wood et al. 1991; Bergholtz 1992). Gastrointestinal testing showed that olestra has no significant effect on bowel movement, total transit time, or pancreatic response. Olestra is not metabolized by gut microflora in anaerobic conditions, nor does it affect the fermentation of other substrates by microflora in the colon (Huck et al. 1994).
Many clinical studies have shown that olestra has potential to benefit some individuals. For example, replacement of conventional fat with olestra can benefit people at high risk of cardiovascular disease, coronary heart disease, obesity, and colon cancer by helping them to lower total fat intake and blood cholesterol level, and to lose weight (Crouse and Grundy 1979; Glueck et al. 1979, 1983; Grundy et al. 1986; Jandacek et al. 1990; Patterson et al. 2000; Bray et al. 2002; Roy et al. 2002).
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