Lipid-Based Fat Replacers

Fewer calories (kcal) can be derived from fats if their molecular structure is modified so they are not absorbed as well, or if the length of fatty acids on the glycerol molecule is reduced. It is known that short- and medium-chain fatty acids provide fewer calories (kcal) than larger ones, which is why butyric acid, with only four carbon atoms, yeilds fewer calories (kcal) than palmitic acid, which contains sixteen carbons. These two principles are applied in the manufacture of the lipid-based fat replacers known as caprenin and salatrim. Caprenin’s reduction in calories (kcal) is due, in part, to the presence of short and medium fatty acids. This fat replacer is used in candy manufacturing, and currently replaces some of the cocoa butter. It achieves these lower calori values due to its short-chain fatty acids and one long-chain fatty acid, which is only partially absorbed.

Lipid-based fat replacers also include extenders, which replace a larger amount of fat with a smaller quantity of fat. Extenders can reduce the soybean oil content in mayonnaise, sandwich sauces, and spoonable salad dressings by 67 to 75 percent. Adding emulsifiers, which are occasionally lipid-based, is another way to simulate the palatability of fats.

One of the most recent fat replacers on the market is Olestra. This unique compound was discovered by accident by Fred Hugh Mattson, a research chemist for Procter & Gamble. Company researchers were trying to locate an easily digested fat for premature infants, but instead found a compound that the body does not break down at all. Previously known as sucrose polyester, Olestra gained FDA approval in 1996 and is marketed under the brand name Olean. It is made from sugar and vegetable oil in a process in which the three-carbon glycerol molecule in the oil is replaced by a six-carbon sucrose, with six to eight fatty acids attached. This molecule is so large that it moves through the digestive tract before enzymes have time to digest the fatty acids.

Besides being undigested, Olestra is stable during heating and can even withstand the high temperatures of frying. Food companies use it in a variety of snack foods such as crackers, potato and tortilla chips, fried and baked goods, and dairy products.