Changes of digestible starch composition and improvements of prebiotic properties in modified taro starch by heat treatment

Abstract

This study investigated the composition of digestible starch and prebiotic properties of taro starch due to different heating treatments. The taro starch has been treated by annealing (24 hrs, 50 °C), heat moisture treatment (moisture 25%, 3 hrs, 110 °C), and autoclaving (15 min, 121 °C) with cooling (24 hrs, 4 °C) for 1, 2, and 3 cycles. Results showed that resistant starch (RS) and slowly digestible starch (SDS) contents in the modified taro starches (MTS) by all heat treatments increased significantly. Furthermore, MTS by autoclaving-cooling two cycles (AC-2C) showed the best prebiotic properties indicated by high resistance in simulated gastric acid (90.19%), high prebiotic effect (2.45), high prebiotic index (1.96) as well as prebiotic activity (0.072) towards Enteropathogenic Escherichia coli (EPEC). This MTS also has high RS (21.34%) and SDS (27.17%) content as well as low digestibility (64.41%). Hence, AC-2C MTS is very prospective to be used as the prebiotic source.

Keywords

• digestible starch
• heat treatment
• modified taro starch
• prebiotic activity
• prebiotic index