Starch amylose-amylopectin ratio

Similar materials are available based on potato starch, eg, PaseUi SA2 which claims DE below 3 and has unique properties based on its amylose—amylopectin ratio pecuhar to potato starch. The product contains only 0.1% proteia and 0.06% fat which helps stabilize dried food mixes compounded with it. Another carbohydrate raw material is waxy-maize starch. Maltodextrias of differeat DE values of 6, 10, and 15, usiag waxy-maize starch, are available (Staley Co.). This product, called Stellar, is offered ia several physical forms such as agglomerates and hoUow spheres, and is prepared by acid modification (49). Maltodextrias based oa com starch are offered with DEs of 5, 10, 15, and 18 as powders or agglomerates (Grain Processing Corp.). 

It is obviously important that the fractionation products should be adequately characterized. The only accurate method for ascertaining the purity of the starch components, and also the amylose/amylopectin ratio in whole starch, is to determine potentiometrically the amount of iodine bound.8 38 Colorimetric methods which have been suggested37 38 are useful for comparative measurements, but are often not absolute. The yield of... 

Leeman, A. M., Karlsson, M. E., Eliasson, A. -C., Bjork, I. M. E. (2006). Resistant starch formation in temperature treated potato starches varying in amylose/amylopectin ratio. Carbohydrate Polymers, 65, 306-313. 

Efforts in genomics have also been directed at manipulation of starch synthesis to modify the amylose amylopectin ratio to increase susceptibility to a-amylase digestion (Smallwood, 2006), in this case to improve ethanol production via fermentation. Such developments would also have spin-offs for other industrial uses of starch where there is a preference for amylose or amylopectin forms. 

The functionality of rice starch depends on the amylose amylopectin ratio. Differences among rice starches made from long-, medium- or short-grain rice are insignificant relative to the amylose content. Rice starches made from common rice tend toward higher peak, cooked and cooled viscosities, as well as paste textures that are short and pasty. The texture of waxy rice starch pastes tends to be long and stringy (Table 13.3). 

Historically, chemical modification of starch was the first widely-investigated method for producing starch-based plastics. Attempts at forming cast films from starch or amy-lose showed that the properties were highly dependent on relative humidity the films became brittle at low humidities.4 Figure 19.2 shows data for films of various amylose/ amylopectin ratios conditioned at 50% relative humidity and 23°C. Efforts to overcome... 

Mayer, J. M. (1993). Processability and characterization of starch-blend films produced using different starch sources and amylose amylopectin ratios. 206th National Meeting, Am. Chem. Soc., Div. Food Agric. Sci., Chicago, IL, Abstract 129. 

In many foods, both starch and protein can be encountered so that understanding interactions between them would be useful. The selectivity in interaction between proteins and starches is best seen in results of dynamic rheological studies. The results depend upon the molecular structure of protein, the starch state of the granules and the amylose/amylopectin ratio, the composition of protein and starch, as well as the phase transition temperatures are important factors influencing protein-starch interaction. Because proteins and starches are thermodynamically different polymers, their presence together may lead to phase separation, inversion, or mutual interaction with significant consequences on texture (Morris, 1990). 

Addition of gluten to 6.5-6.6% (w/w) dispersions of different starches at a 1% level ealeulated on dry stareh basis inereased the G of wheat and rye starches, lowered that of maize stareh but did not affeet the modulus of barley, triticale and potato starehes (Lindahl and Eliasson, 1986). G was also found to increase with increasing amounts of gluten (1-4%) added to the wheat starch. Studies on starches with different amylose/amylopectin ratios suggest that gelatinization of amylopectin and not amylose favors a synergistie interaetion with proteins leading to an increase in dispersion viscosity (Chedid and Kokini, 1992 Madeka and Kokini, 1992). 

Statches ftom different plant sources differ in their amylose/ amylopectin ratio. For example, com starch contains about 27% amylose, potato starch about 22%, and tapioca statch about 17%. In contrast, waxy com statch contains almost entirely amylopectin, with no amylose. These diffetences modify the physical properties of the statches such that the various types may not be interchangeable in a given pharmaceutical application. For example, amylose-rich maize starch has been studied as a potential tablet film-coating ingtedi-... 

It is commonly believed that it is amylose that forms complexes with hpids, but complexation, which occurs concomitantly with the endothermic gelatinization, has been identified and provided evidence of the existence of amylopectin-lipid interactions (Ehasson, 1994). Apparent starch amylose content correlated well with enthalpies of amylose-lipid complexes (Villwock et al., 1999). Lipids are most likely to complex with amylopectin to the extent they do with amylose. The interaction depends on the amylose amylopectin ratio. If amylose is present, the first interaction is that between amylose and lipids, followed by a lipid-amylopectin interaction. This is a mixture of B- and V-pattem starches. The best complexes are formed by 100% amylopectin poorer complexes occur in a 50% solution due to the presence of amylose (Gudmudsson and Eliasson, 1990). 

The amylose/amylopectin ratios and amylose DP differ for different starches. 

J. M. Herrero-Martinez, P. J. Schoenmakers, and W. Th. Kok, Determination of the amylose-amylopectin ratio of starches by iodine-affinity capillary electrophoresis, J. Chromatogr. A, 1053 (2004) 227-234. 

Starch Plastic Starches can be converted into thermoplastic or thermoset materials. Properties of the individual starches vary depending upon the size and shape of the granules and the amylose/amylopectin ratio. Amylose is a mostly linear chain, and amy-lopectin is a branched glucan. Most starches eontain approximately 20% amylose. " ... 

It has been demonstrated that an extrusion-cooked starch can be solubilized without any formation of maltodextrins and that the extent of solubilization depends on exttusion temperature, moisture content of the starch before extrusion and amylose/amylopectin ratio. For instance, Mercier et al. [39] determined the properties of different types of starch and considered the influence of the following parameters in a short twin-screw extrader moisture content between 10.5 and 28%, barrel temperature between 65 and 250 °C, residence time between 20 seconds and 2 minutes. It was demonstrated that com starch, after extrusion cooking, gave a solubility lower than 35%, while potato starch solubility was up to 80%. 

For example, destructurized starch and vinyl alcohol copolymer composites, materials containing starch with an amylose/amylopectin ratio above 20/80 w/w do not dissolve even under stirring in boiling water. Under these conditions a microdispersion constituted by microsphere aggregates is produced, whose individual particle diameter is lower than 1 pm (Figure 2.5). 

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