A Study of the Optimal Conditions for Starch Hydrolysis Through Thermostable Α - Amylase
T. Kolusheva, A. Marinova Journal of the University of Chemical Technology and Metallurgy, 42, 1, 2007, 93-96
A STUDY OF THE OPTIMAL CONDITIONS FOR STARCH HYDROLYSIS THROUGH THERMOSTABLE α - AMYLASE
T. Kolusheva, A. Marinova
University of Chemical Technology and Metallurgy 8 Kl. Ohridski, 1756 Sofia, Bulgaria E-mail: e-mail: manahova@abv.bg.
Received 10 July 2006 Accepted 12 November 2006
ABSTRACT The present work determines the optimal conditions for starch hydrolysis by thermostable α -amylase (EC 3.2.1.1) produced by Bac.subtilis strain XÊ-86. The hydrolysis reaction has the greatest rate at pH = 7.0, starch substrate concentration 250 g.l-1, enzyme concentration 12 enzyme units per ml suspension and 90o C temperature. We show that the enzyme is inhibited by high concentrations of the substrate (above 250 g.l-1), as well as by glucose. We establish that the enzyme under consideration gives a high reaction rate of the hydrolysis and high concentration of the reducing sugars in a relatively short period of time 4 hours and 15 min. Keywords: starch hydrolysis, thermostable α - amylase.
INTRODUCTION Starch hydrolysis is a widely used process in various industries. The production of low molecular mass products from starch substrate underlies the sugar, brewing, spirits, textile, some food processing and other industries. At present starch hydrolysis is carried out in two basic ways acidic and enzymatic. The older and more traditional method is acidic hydrolysis which requires highly acidic medium (pH = 1 2) obtained through mineral acids; high temperatures (150 230o C) and high pressure [1 - 4]. As a result of the thermal processing, acidic hydrolysis produces unnecessary byproducts which contaminate the end-product hydrolysate. The enzymatic hydrolysis of starch is carried out under milder conditions: lower temperatures (up to 100o C), normal pressure, pH of the medium around 6 8 [2, 5, 6]. At the same time enzymatic hydrolysis is
A STUDY OF THE OPTIMAL CONDITIONS FOR STARCH HYDROLYSIS THROUGH THERMOSTABLE α - AMYLASE
T. Kolusheva, A. Marinova
University of Chemical Technology and Metallurgy 8 Kl. Ohridski, 1756 Sofia, Bulgaria E-mail: e-mail: manahova@abv.bg.
Received 10 July 2006 Accepted 12 November 2006
ABSTRACT The present work determines the optimal conditions for starch hydrolysis by thermostable α -amylase (EC 3.2.1.1) produced by Bac.subtilis strain XÊ-86. The hydrolysis reaction has the greatest rate at pH = 7.0, starch substrate concentration 250 g.l-1, enzyme concentration 12 enzyme units per ml suspension and 90o C temperature. We show that the enzyme is inhibited by high concentrations of the substrate (above 250 g.l-1), as well as by glucose. We establish that the enzyme under consideration gives a high reaction rate of the hydrolysis and high concentration of the reducing sugars in a relatively short period of time 4 hours and 15 min. Keywords: starch hydrolysis, thermostable α - amylase.
INTRODUCTION Starch hydrolysis is a widely used process in various industries. The production of low molecular mass products from starch substrate underlies the sugar, brewing, spirits, textile, some food processing and other industries. At present starch hydrolysis is carried out in two basic ways acidic and enzymatic. The older and more traditional method is acidic hydrolysis which requires highly acidic medium (pH = 1 2) obtained through mineral acids; high temperatures (150 230o C) and high pressure [1 - 4]. As a result of the thermal processing, acidic hydrolysis produces unnecessary byproducts which contaminate the end-product hydrolysate. The enzymatic hydrolysis of starch is carried out under milder conditions: lower temperatures (up to 100o C), normal pressure, pH of the medium around 6 8 [2, 5, 6]. At the same time enzymatic hydrolysis is
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