Operational Stability of Glucoamylase in Continuously Operated Ultrafiltration Membrane Reactor – Experimental Methods and Mathematical Model

M. Tusić, M. Sudar, Z. Findrik Blažević and Đ. Vasić-Rački

Abstract
Operational stability of glucoamylase was studied at 45, 60 and 70 °C in the reaction of maltose hydrolysis. The experiments were carried out in a continuously operated ultrafiltration membrane reactor (UFMR) at constant residence time of 176.5 minutes. The rate of enzyme operational stability decay increased with temperature. This could be quantitatively observed from the measurements of volume activity during the experiments, which were used to estimate enzyme operational stability decay rate constants. The results have shown that stationary conditions in UFMR can be maintained if sufficiently high enzyme concentration is used in the reactor, regardless of the enzyme operational stability decay that occurs. This was shown by the experiment carried out at 45 °C where it was proved that the enzyme operational decay occurs even though maltose conversion was at maximum during the entire experiment. Thus, the operational stability decay can be masked.

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Keywords
biotransformation, Dextrozyme, ultrafiltration enzyme membrane reactor, enzyme activity, enzyme operational stability decay