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Food Chem. 2013 Jan 15;136(2):689-94. doi: 10.1016/j.foodchem.2012.08.074. Epub 2012 Sep 9.

Batch and continuous synthesis of lactulose from whey lactose by immobilized β-galactosidase.

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  • 1Department of Chemical and Biological Engineering, Korea University, 5 Ga, Anam-dong, Sungbuk-gu, Seoul 136-701, Republic of Korea.

Abstract

In this study, lactulose synthesis from whey lactose was investigated in batch and continuous systems using immobilized β-galactosidase. In the batch system, the optimal concentration of fructose for lactulose synthesis was 20%, and the effect of galactose, glucose and fructose on β-galactosidase activity was determined for hydrolysis of whey lactose and the transgalactosylation reaction for lactulose synthesis. Galactose and fructose were competitive inhibitors, and glucose acted as a noncompetitive inhibitor. The inhibitory effects of galactose and glucose were stronger in the transgalactosylation reaction than they were in the hydrolysis reaction. In addition, when immobilized β-galactosidase was reused for lactulose synthesis, its catalytic activity was retained to the extent of 52.9% after 10 reuses. Lactulose was synthesized continuously in a packed-bed reactor. We synthesized 19.1g/l lactulose during the continuous flow reaction at a flow rate of 0.5 ml/min.

Copyright © 2012 Elsevier Ltd. All rights reserved.

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