Publication no. C-2001-0808-03R |  VIEW ARTICLE

Synergistic Hydrolysis of Crude Corn Starch by alpha-Amylases and Glucoamylases of Various Origins.

Maria Liakopoulou-Kyriakides (1,2), Athanasios Karakatsanis (1), Michael Stamatoudis (1), and Stavros Psomas (1). (1) Department of Chemical Engineering, Aristotle University of Thessaloniki, Thessaloniki 54006, Greece. (2) Corresponding author. Fax: +3031 996193, E-mail: <markyr@vergina.eng.auth.gr> Cereal Chem. 78(5):603-607. Accepted May 16, 2001. Copyright 2001 American Association of Cereal Chemists, Inc.

Four alpha-amylases and two glucoamylases from various sources, in eight combinations, were used to study the synergistic hydrolysis of crude corn starch at various temperatures. At 40 and 50°C, the combinations containing Rhizopus mold glucoamylase enhanced hydrolysis of corn starch compared wth that obtained with the combinations from Aspergillus niger. At 60°C, Rhizopus mold combinations gave low reaction yields as the enzyme was inactivated. The differences observed between alpha-amylases are smaller, with the exception of Bacillus licheniformis alpha-amylase, which presented more than twice the productivity of the other alpha-amylases, at all temperatures. In terms of substrate conversion at 5 hr of hydrolysis, the combination of B. licheniformis alpha-amylase with Rhizopus mold glucoamylase at 50°C presents 76% substrate conversion, whereas, with all the other combinations, starch conversion was 13-73%. HPLC analysis of the reaction products obtained at 50°C showed that the main product of corn starch hydrolysis was glucose at 85-100%. Further experiments showed that A. niger glucoamylase and B. licheniformis alpha-amylase were the only enzymes that retained their initial activity after incubation at the temperatures studied.