Optimization of an enzymatic procedure for the hydrolytic depolymerization of amaranth starch by response surface methodology

Abstract

This study reports the effect of alpha-amylase concentration (0.01 to 0.05 mL/100 g), hydrolysis time (5 to 15 min) and incubation temperature (65 to 80°C) on dextrose equivalent (DE) and protein content after liquefaction of amaranth whole flour and an evaluation of the effect of amyloglucosidase concentration (0.05 to 0.6 mL/100 g) plus a fixed percentage of pullulanase (0.03 mL/100 g) and of incubation time (12 to 60h) on DE and protein content of saccharified samples which were previously treated by liquefaction. Response surface methodology was used for this evaluation. Dextrose equivalent was affected (P < 0.06) by both linear and quadratic enzyme concentration terms, while hydrolysis time and hydrolysis temperature affected (P < 0.06) DE by linear and quadratic terms, respectively. The protein content of the liquefied flour was only affected (P < 0.02) by the linear and quadratic terms for hydrolysis time. After saccharification it was found that DE was affected by enzyme (P < 0.01) linear and quadratic concentration terms, while the hydrolysis time effect was only linear (P < 0.01). The protein content of the saccharified flour was affected (P < 0.11) by the linear and quadratic terms for hydrolysis time and enzyme concentration, respectively. Confirmatory tests showed that the regression equations which were generated can adequately predict the performance of the liquefaction and saccharification procedures. © 1993 Academic Press Limited.