Polysaccharides digestion

Table 9.7, Performance Characteristics, Total Tract Nonstarch Polysaccharide Digestibility, and Dietary Nitrogen-Corrected Apparent Metabolizable Energy Concentration of Enzyme-Treated Diets Fed to Broilers (5-18 d) ...

Mixed Polysaccharides Digestion, Absorption, and Metabolism Functions Energy... 

Starch is a polysaccharide found in many plant species. Com and potatoes are two common sources of industrial starch. The composition of starch varies somewhat in terms of the amount of branching of the polymer chains (11). Its principal use as a flocculant is in the Bayer process for extracting aluminum from bauxite ore. The digestion of bauxite in sodium hydroxide solution produces a suspension of finely divided iron minerals and siUcates, called red mud, in a highly alkaline Hquor. Starch is used to settle the red mud so that relatively pure alumina can be produced from the clarified Hquor. It has been largely replaced by acryHc acid and acrylamide-based (11,12) polymers, although a number of plants stiH add some starch in addition to synthetic polymers to reduce the level of residual suspended soHds in the Hquor. Starch [9005-25-8] can be modified with various reagents to produce semisynthetic polymers. The principal one of these is cationic starch, which is used as a retention aid in paper production as a component of a dual system (13,14) or a microparticle system (15). 

Historically, dietary fiber referred to iasoluble plant cell wall material, primarily polysaccharides, not digested by the endogenous enzymes of the human digestive tract. This definition has been extended to iaclude other nondigestible polysaccharides, from plants and other sources, that are iacorporated iato processed foods. Cellulose [9004-34-6] (qv) is fibrous however, lignin [9005-53-2] (qv) and many other polysaccharides ia food do not have fiberlike stmctures (see also Carbohydrates). 

Fiber components are the principal energy source for colonic bacteria with a further contribution from digestive tract mucosal polysaccharides. Rate of fermentation varies with the chemical nature of the fiber components. Short-chain fatty acids generated by bacterial action are partiaUy absorbed through the colon waU and provide a supplementary energy source to the host. Therefore, dietary fiber is partiaUy caloric. The short-chain fatty acids also promote reabsorption of sodium and water from the colon and stimulate colonic blood flow and pancreatic secretions. Butyrate has added health benefits. Butyric acid is the preferred energy source for the colonocytes and has been shown to promote normal colonic epitheUal ceU differentiation. Butyric acid may inhibit colonic polyps and tumors. The relationships of intestinal microflora to health and disease have been reviewed (10). 

Unlike many of the catalysts that chemists use in the laboratory, enzymes are usually specific in their action. Often, in tact, an enzyme will catalyze only a single reaction of a single compound, called the enzyme s substrate. For example, the enzyme amylase, found in the human digestive tract, catalyzes only the hydrolysis of starch to yield glucose cellulose and other polysaccharides are untouched by amylase. 

The polysaccharides are polymers of glucose. They include starch, which we can digest, and cellulose, which we cannot. Starch is made up of two components ... 

Phytochemicals influence other digestive secretions. Several traditional herbal medicines stimulate gastric mucous secretion, providing protection (Sairam et al., 2001). The secretion and recycling of bile are also responsive to phytochemicals. The way in which certain polysaccharides increase fecal concentrations of bile acids (DalT Angelo and Lino van Poser, 2000) and thereby influence recycling and synthesis is particularly noteworthy. 

LONGSTAFF M, MCNAB J M (1991) The inhibitory effects of hull polysaccharides and tannins of field beans (Vida faba L.) on the digestion of amino acids, starch and hpid and on digestive enzyme activities in young chicks. Br. TNutr. 65 199-216. 

Pectic polysaccharides were released from total walls by digestion with endopolygalacturonase... 

The objective of the project described is to obtain insight in the relation between the chemical fine-structure of polysaccharides from soy bean cell walls and their functional properties in industrial products and how they effect processing. Soy meal is of great importance in the feed industry. The application of the (modified) soy bean cell wall polysaccharides as a food additive will be investigated. The obtained knowledge of the polysaccharide structures will also be used in studies concerned with the improvement of the in vivo digestibility of these polysaccharides. 

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