Starch polysaccharide components

ITie work described in this chapter was initiated to determine the kinetics of enzymatic and microbial attack on blends containing starch and LDPE or starch, LDPE, and EAA. From the initial studies came a more general goal of identifying structural and compositional characteristics of blends (in general) that facilitate or retard degradation of the polysaccharide component. 

A debranching enzyme called isoamylase is involved in synthesis of the starch granule and its polysaccharide components (34-37). Mutant plants deficient in isoamylase activity accumulate a soluble a-glucan designated phytoglycogen (3, 37, 38) and little starch. 

The presence of numerous hydroxyl groups able to react with formaldehyde makes starch-derived products suitable chemicals for formaldehyde-based resins. Research on this subject started many years ago and showed that in a number of applications it is possible to partially replace or extend urea formaldehyde, phenol formaldehyde and melamine formaldehyde resins without significantly affecting the finished product s performance. In many applications, adhesive systems based on formaldehyde resins incorporate a polysaccharide component. More than 4.5 Mio mto of formaldehyde-based resins have been produced in Western Europe alone. The use of carbohydrates allows lower consumption of oil-based resins and, consequently, reduced release of formaldehyde in the environment. 

Non-starch polysaccharides (NSP) Plant cell-wall NSP Other NSP Many different types of polysaccharides Main constituents arabinose, xylose, mannose, galactose, glucose, uronic acids Many types of constituents Escape digestion in the small intestine and are fermented to different extents Encapsulate and slow absorption of nutrients. Good marker for naturally fiber-rich diets for which health benefits have been shown Food additives. Minor components of the human diet. The amounts added to foods are known and regulated... 

Starches also contain minor components such as protein (0.05-0.5 Wt%), lipids (0.1-1.7 wt%), inorganic substances (0.1-0.3 wt% of ash), and non-starch polysaccharides (Liu 2005), which can interact with many additive components (Baker et al. 1994 Garcia et al. 1998). This makes them widely used in packaging industry, because in addition to protecting the products against shock and vibration that occur during transport, they can impart antioxidant and/or antimicrobial properties. 

There are a number of other polysaccharides in foods. Collectively they are known as non-starch polysaccharides, the major components of dietary fibre (section 7.3.3.2). Non-starch polysaccharides are not digested by human enzymes, although all can be fermented to some extent by intestinal bacteria, and the products of bacterial fermentation may be absorbed and metabolized as metabolic fuels. The major nonstarch polysaccharides (shown in Figure 4.8) are ... 

Non-starch polysaccharides have little nutritional value in their own right, as they are compounds that are not digested or absorbed to any significant extent. Nevertheless, they are a valuable component of the diet, and some of the products of fermentation by colonic bacteria can be absorbed and utilized as metabolic fuel. Together with non-starch polysaccharides, we have to consider that proportion of starch that is (relatively) resistant to digestion in the small intestine (section 4.2.2.1), because it too is a substrate for bacterial fermentation. 

A number of phytochemicals, which are commonly found in foods, has been listed in Table 13.1. Besides, essential oils, non-starch polysaccharides/oligosaccharides, polyunsaturated fatty acids (PUFA) are other bioactive components of foods which are of special interest. 

Polysaccharides are made from linking multiple monosaccharide units. These long chain molecules are known as starch in the plant system and glycogen in the animal system. Starch polysaccharides primarily contain a-glucans. These include amylose, amylopectin, modihed starches, and resistant starches. Fiber, also known as nonstarch polysaccharides (NSP), primarily contains components derived from the plant cell wall such as cellulose, hemiceUulose, and pectin. Other polysaccharides include gums and hydrocoUoids. 

Rafftnose, a galactooligosaccharide, is prevalent in legumes, including lentils, dried beans, and soy. Starch is present in many dietary staples, including potatoes, bread, pasta, and rice. Cellulose, a structural component of cell walls, is the primcay component of celery. Hemicellulose is a structural polysaccharide component in the cell walls of many organisms. 

Total daily carbohydrate intake in the UK is about 277 g in which 110 g is monosaccharides or disaccharides such as sucrose, fructose, glucose, etc. These are relatively easy to isolate analytically. The rest of food carbohydrate is polysaccharide (about 167 g) of which starch (148 g) is the major component. The non-starch polysaccharides (18 5 g) are the major part of what is commonly called dietary fibre. 

The non-starch polysaccharides can themselves be subdivided into various components. Ideally each different polysaccharide should be identifiable, but at the present time only cellulose can be isolated with any confidence. The non-cellulosic polysaccharides may be hydrolysed and their overall monosaccharide composition determined by gas-liquid chromatography. Whilst giving no clue as to the physical nature of the carbohydrate polymers present, this procedure may yield useful information, since it has been shown that the faecal... 

Leek, A.B.G., J.J. Callan, P. Reilly, V.E Beattie and J.V. O Doherty, 2007. Apparent component digestibility and manure ammonia emission in finishing pigs fed diets based on barley, maize or wheat prepared without or with exogenous non-starch polysaccharide enzymes. Anim. Feed Sci. Technol. 135, 86-99. 

Structure of the polysaccharide components of starch, amylose (a) and amylopectin (b). 

Maltosaccharides, containing up to about 10 - AGU, [CsHioOs] 10 are called m. and are components of - hydrolysis products of -+starch polysaccharides by means of acids or enzymes (- glucose syrups, - maltose syrups). 

The starch components - amylose and amylo-pectin are not to be considered as m. because they represent pure, unmodified - -starch polysaccharides. They can be converted, however, into modified products, preferentially by the above-cited chemical treatments. 

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