Starch, /3-amylase action

Table I. Oligosaccharide Compositions Prepared from Starches by Thermal Stable Alpha-Amylase Actions ...

The commercial importance of amylolytic enzymes is rapidly increasing. These enzymes catalyze the hydrolytic reactions of amylose (unbranched starch) and amylopectin (branched starch). Amylases, according to their difference in modes of action, can be divided into ... 

It has been supposed that the amylase action leads to an equilibrium between starch and maltose or between maltose and certain dextrins. This is not the case, for if the limit dextrins are isolated and treated with amylase no action or at most only an extremely slow action is observed. 

It must be conceded that there is one case where the products of amylase action are probably not primary products formed in this way. This is the degradation of starch with the amylase from Bacillus macerans. The cycloamyloses formed by this enzyme are probably not preformed in the starch (see also Section II, 10). 

Robyt JF, Whelan WJ (1968) General Aspects of Amylase Action, Chap. 13 cr-Amylases, Chap. 14 /J-Amylases. In Radley JA (ed) Starch and Its Derivatives, 4th edn. Chapman and Hall, London, pp 477-497... 

In an attempt to account for the eventual production of low molecular-weight reducing sugars from starch by B. macerans amylase action, Cramer and Steinle propose the following scheme. ... 

Uncooked starch is resistant to amylase action, because it is present as small insoluble granules. The process of cooking swells the starch granules, resulting in a gel on which amylase can act. However, as cooked starch cools, a proportion undergoes crystallization to a form that is again resistant to amylase action — this is part of the process of staling of starchy foods. 

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