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Published on: October 14, 2013
Hydrolysis of concentrated raw starch: A new very efficient α-amylase from Anoxybacillus flavothermus
Georges Tawil1, Anders Viksø-Nielsen2, Agnès Rolland-Sabaté1
1Unité Biopolymères, Interactions, Assemblages, Institut National de la Recherche Agronomique, Rue de la Géraudière, BP 71627, F-44316 Nantes Cedex 3, France.
Abstract:
A new α-amylase from Anoxybacillus flavothermus (AFA) was found to be effective in hydrolyzing raw starch in production of glucose syrup at temperatures below the starch gelatinization temperature. AFA is very efficient, leading to 77% hydrolysis of a 31% raw starch suspension. The final hydrolysis degree is reached in 2-3h at starch concentrations lower than 15% and 8-24h at higher concentrations. AFA is also very efficient in hydrolyzing the crystalline domains in the starch granule. The major A-type crystalline structure is more rapidly degraded than amorphous domains in agreement with the observed preferential hydrolysis of amylopectin. Amylose-lipid complexes are degraded in a second step, yielding amylose fragments which then re-associate into B-type crystalline structures forming the final α-amylase resistant fraction. The mode of action of AFA and the factors limiting complete hydrolysis are discussed in details.
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