Effects of processing conditions on hydrolysis of cassava starch

Abstract

Different procedures for hydrolyzing raw cassava starch were studied, namely: acid, acid-enzyme and enzyme-enzyme hydrolysis. The effects of temperature, initial cassava starch concentration, acid concentration and time on acid hydrolysis using dilute hydrochloric acid were investigated. In addition, the effect of initial cassava starch concentration and time on acid-enzyme hydrolysis with HCl/fungalmyl/amyloglucosidase and HCl/termamyl/amyloglucosidase as well as the enzyme-enzyme hydrolysis with fungalmyl/amyloglucosidase and termamyl/amyloglucosidase were also investigated and the local optimum operating conditions and the yield from the three methods were compared. The results showed that in acid hydrolysis the local optimum operating conditions were: 15% cassava starch concentration, 0.5M HCl, at 70 oC and 10 h operating time which produced 32.5 g/l reducing sugar concentration and dextrose equivalent (DE) of 22. The acid-enzyme hydrolysis with HCl/fungalmyl/amyloglucosidase, using 30% initial cassava starch concentration and total effective operating time of 50 h, produced 72 g/l reducing sugar concentration and DE of 24.8 and was the better of the two acid-enzyme hydrolysis studied. The best procedure was the enzyme-enzyme hydrolysis with termamyl/amyloglucosidase using 30% initial cassava starch concentration, which produced 152 g/l reducing sugar concentration and DE of 50.9. The total effective operating time was 60 h.

Keywords:Cassava starch, hydrolysis, enzyme, dextrose equivalent.

Ifr Journal of Science Vol. 8 (2) 2006: pp. 115-126