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SUSCEPTIBILITY OF VARIOUS STARCH TYPES TO AMYLOLYTIC ENZYMES

Alexander Papakhin

Abstract

It was studied susceptibility of starch granules of different types to hydrolysis by enzymes both in the gelatinized and native state. Starch was evaluated by chemical composition, morphology, physical and chemical properties and compared with respect to the action of amylolytic enzymes traditionally used to produce sugary starch products (alpha-amylase, glucoamylase). Enzymatic susceptibility of the samples was evaluated by accumulation of reducing matters during the hydrolysis of 1% starch suspension in gelatinized and native state. It was found that during gelatinization and liquefaction barley and oat starches had the greatest susceptibility to alpha-amylase achieving glucose equivalent (GE) ? 28.6% and 25.6%, respectively), the lowest susceptibility was in potato, rye, rice and pea starches had GE ? 18.7, 18.2, 18.3%, respectively. The degree of hydrolysis during liquefaction for normal corn, amylopectin corn, sorghum and wheat starches was 20-22%. The maximum glucoamylase effect of all tested samples of gelatinized starchwas 96.5 ± 0.5% DS. During the biocatalysis of starch by glucoamylase in non-gelatinizedstate amylopectin corn starch had the maximum susceptibility with a hydrolysis degree(HD) of 73.7%, a reduced susceptibility was revealed in pea, barley starches (GE - 32.0-34.1%), and a minimal value (11.7%) was in potato starch. In other types of cereal starch,the enzymatic susceptibility was estimated by the degree of hydrolysis of 35-52%. Thedata obtained are necessary to choose alternative types of cereal raw materials for theproduction of a diverse range of sugary starch products and modified starch.

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