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Updated: Thursday, September 6, 2007.
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Excerpts Novel carbohydrates are finding new applications these days, as researchers are better able to describe them and determine their specific attributes. And new methods of analyzing carbohydrate structure allow development scientists to match these products with appropriate manufacturing methods.
Many fruits and vegetables, for example, provide a wonderful stew of carbohydrates: sucrose, fructose, linear starches, branched starches, pectins and hemicelluloses, all packed in highly specific packages. Some of these interactive carbohyrates are found in waste portions of fruits processed in large quantity and have gone to market as functioning ingredients, affecting texture, viscosity and flavor of products. They are now being studied as nutritional adjuncts, as well.
Includes information regarding: pectin and oligosaccharides profiles.
Pectin Profiles Pectin is one such compound currently harvested for gelling and viscosifying. Pectin, a multi-branched carbohydrates, is often harvested from citrus peel and apple pumice. Pectin is a polymer of partially methoxylated alpha, 1,4-linked D-galacturonic acid that is interrupted by dispersed or alternating 1,2 linked L-rhamnose units that are linked to neutral sugars such as L-galactose and L-arabinose. In simple terms, the different sugars (all of those 'oses are sugars of differing shape that occur naturally in various fruits) are arranged in such a way that they form a gel with water, and have a particular tender texture.
But pectin does more than make jam. It was reported several years ago to be effective in lowering serum cholesterol levels, and several studies have shown that pectin binds with bile acids, which are the catabolic products of cholesterol, andmodulates serum cholesterol.
Because specific regions of pectin can be attacked by specific enzymes, and because most of these enzymes are known, the textural characteristics of pectin can be altered to fit a variety of needs. And because the enzymes are known, the possibility of changing the pectin within the plant is also quite conceivable.
A compound that includes pectin, in an insoluble form, is referred to as protopectin. Work done on this fractionof common foods (particularly potato, garlic, ginger, and red peppers) at the University of Osaka in Japan found that the pectin-like substances become soluble after restricted degradation of naturally occurring polygalacturonic acid chains with protopectinase. Products may be candidates for use as thickeners and texturizers, and may have specific use as dietary fiber.
USDA eastern regional scientists are working with pectin and additional ingredients (particularly proteins) to develop film forming attributes that may be used one day to extend shelf life of products and reduce packaging layers. The use of pectin as a viscosifier with a particular fat-like texture is being explored in a number of products.
Oligosaccharides
A group of short chain polysaccharides that are not digestible by stomach acids are being evaluated by a number of organizations as food ingredients. Terminology appears to be a little unspecified; they are referred to by a number of names. In general, the small sugars have low molecular weights, add only small amounts of viscosity to a product, and are water-soluble dietary fibers.
The fructooligosaccharides (or whatever your favorite term for the little carbohydrates may be) are naturally occurring in foods like onion, garlic, asparagus, chicory and Jerusalem artichoke. They have excited interest in a couple of areas: They have been noted in the literature as fat replacers, and suggested as the basis for increasing bifidobacteria (part of the intestinal flora in the colon) that bind bile acids and protect liver function. According to feeding studies done in Osaka, amounts as small as three grams of the fructooligosaccharides are said to effectively reduce blood pressure in some subjects.
Oligosaccharides from a number of sources are available in different forms. Inulin, extracted from jerusalem artichoke or by manipulating starch sources, is available under a variety of designations. Oligosaccharides have been defined by at least one source as materials that contain not only fructose with five to 200 fructose units, or that may contain minor amounts of other saccharides, such as glucose, fructose and disaccharides such as sucrose. The compounds may also be derived from micro-organisms including Aspergillus sydowii. A fructooligosaccharide made from sucrose by enzyme treatment provides at least 95% fructooligosaccharides on a dry weight basis. The material, developed by Golden Technologies Co. Inc., Westminster, Colo., looks like table sugar and is mildly sweet.
Still more work is being done on inulin, fractionating away the small sugars and producing a product of about 20 monomer units while simultaneously recovering glucose and fructose. The process uses comminuted chicory roots or other plants, demineralizing the material and treating with an enzyme called inulinase to remove the small sugars. The material is under development by Sudzucker AG, Mannheim, Germany, and is described in U.S. patent 5,478,l732.
Further processing of the small carbohydrates is appearing in the technical literature: Patent 5,468,512 issued to Quest International, Hillside, ILL., teaches a pasteurization step to stabiliize the oligofructose materials for improved shelf stability when the materials are used as fat-replacing ingredients.
No-waste tomatoes
Another interesting carbohydrate compound is being developed in Greece at the University of Athens by researchers interested in dealing with tomato processing wastes, of which 50 to 55 percent are tomato seeds. The tomato seeds, currently used as animal feed or fertilizer, contain unsaturated fatty acids, plus a generous amounts of lysine. The carbohydrate fraction is mainly dietary fiber, which is particularly free of antinutritional factors.
A number of feeding studies have indicated that linear carbohydrates of several types are helpful in controlling serum cholesterol, and possibly triglycerides in general. There is less than perfect agreement about which complex carbohydrates are most effective in controlling blood cholesterol levels, insulin levels, and bile acids. In fact, there is less than perfect agreement about how big a carbohdyrate has to be to be complex.
While sematic aspects are being sorted out, these carbohydrate structures appear to be extremely helpful as adjuncts to low-fat foods and in foods that require specific textures.
Updated: Thursday, September 6, 2007. | |||||||||
OSU Disclaimer. |
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