PRODUCTION OF MALTOSE SYRUP BY BIOCONVERSION OF CASSAVA STARCH IN AN ULTRAFILTRATION REACTOR

The use of an ultrafiltration membrane reactor (UFR) for the bioconver sion of cassava starch into maltose was studied. Carbosep membranes wi th cut-offs of 10, 50 and 150 kDa were used. The 50 kDa cut-off membra ne gave the most acceptable results in terms of permeate flux and malt ose content. The enzymes Maltogenase and Promozyme (Novo Nordisk) were used to saccharify and debranch starch. Massive enzyme dosages were r equired to achieve sufficiently high maltose concentrations in the per meate. However, Promozyme showed unexpected poor thermostability. When the UFR was operated with the 50 kDa cut-off membrane and under a sta rch concentration of 30% d.s., the permeate flux could be stabilized a round 20 l h(-1) m(-2) for 6 h by gradually increasing the transmembra ne pressure. The maltose concentration of the permeate was then 217 g l(-1). However, accumulation of unconverted substrate within the react or was observed. (C) 1998 Elsevier Science B.V.