Continuous production of chitooligosaccharides using a dual reactor system

The continuous production of chitooligosaccharides from chitosan was achieved with a dual reactor system which consisted of an ultrafiltration (UF) membrane reactor and a column reactor packed with an immobilized enzyme. The production of the oligosaccharides was performed by two steps, the first, the preparation of the partially hydrolyzed chitosan (PHC) from viscose chitosan in the column reactor packed with an enzyme and the second, the production of the oligosaccharides from PHC in the UF membrane reactor. Three kinds of PHCs were obtained from three different outflow rates (3, 5, and 9 ml/min) in the column reactor and were supplied to a substrate feed tank of the following UF reactor in order to identify the influence of the feed on membrane fouling. The PHC obtained with a 5 ml/min overflow rate was the most suitable substrate for alleviation of membrane fouling and efficient hydrolysis under the operating conditions of the dual reactor system. In addition, chitooligosaccharides produced using the dual reactor system were readily fractionated by a proper selection of membranes. Therefore, it was shown that this dual reactor system was adequate for continuous production of chitooligosaccharides from chitosan by enzymic hydrolysis. (C) 2000 Elsevier Science Ltd. All rights reserved.