Enzymes-Resistant Starch (RS III) from Pullulanase- Debranched High Amylose Rice Starch

Abstract

In this study, a debranching enzyme (Pullulanase, EC. 232-983-9P, 8U/g starch at 55°C for 0 to 48 hr) was introduced to modify the amylopectin molecules of 15% (w/w) high amylose (32.10%) rice starches suspension which were gelatinized at 75°C for 30 min. The result showed that the
retrogradation of debranched starches with different degree of hydrolysis were yielded 0.14 to 1.55% which each samples was then induced at 4°C for 16 hr. Afterward, the one freeze-thaw cycle process (-10/30°C) was applied to promote syneresis of retrograded starches. It was shown that pullulanase hydrolysis improved the degree of retrogradation from 28.10 to 54.53%. The resistant starch content of the RS III sample increased from 4.80 to 12.33% by 0 to 48 hr, respectively. Results showed that after debranching, starch molecule had rearranged and changed their crystal pattern from A to V-type by Xray diffraction analysis. The RS III sample formed a coarse honeycomb-like and filamentous network structure was observed with Scanning Electron Microscope. The estimated hydrolysis index and glycemic index of the RS III samples were between 35.61% to 62.70% and 59.29% to 73.47% respectively.