ENZYMATIC-HYDROLYSIS AND SACCHARIFICATION OPTIMIZATION OF SAGO STARCHIN TWIN-SCREW EXTRUDER

The influence of processing conditions in a combined gelatinisation an d liquefaction extrusion system on subsequent saccharification was exa mined. Extrusion conditions investigated were barrel temperature (70 - 130 degrees C), screw speed (70-190 rpm), enzyme concentration (0-1%) and feed moisture content (28.5-50.5%). Feed moisture, barrel tempera ture and enzyme concentration had significant effects on saccharificat ion, which ranged from 32 to 98% (dextrose equivalent = 83-98) after 8 h reaction with 0.50 AGU/ml amyloglucosidase (AMG). Die pressure tvas negatively correlated with saccharification (r = -0.75), implying tha t products formed from a high viscous mass were poorly saccharified. G reater extent of saccharification was achieved with lower SME input. S accharification in the extruder was initiated by adding AMG during the extrusion processing. Both initial and subsequent saccharification we re dependent on the AMG concentration, moisture content and the stage of AMG addition. In this mixed-enzyme system, synergistic effects of b oth enzymes (alpha-amylase and amyloglucosidase) were evident. High pe rformance size-exclusion chromatography profiles showed that incorpora ting AMG led to loss of G6 and G2 in the oligosaccharide spectra but w ith formation of G5. (C) 1997 Elsevier Science Limited.