Zhu Hong

Relationship among amylose content, starch pasting and ethanol fermentation in sweetpotato varieties for starch use.

Fifteen starch-based sweetpotato varieties were used to test amylose contents (AC), starch pasting properties and ethanol fermentation characteristics, and analyze the difference and relationship among them. The results indicated that there were significant differences among dry matter content, starch content and AC of different sweetpotato varieties, and AC was significantly correlated to dry matter content and starch content. Differences presented among pasting properties in different varieties of sweetpotato, and the relationship among RVA eigenvalues was close. There were significant differences among ethanol fermentation characteristics of different sweetpotato varieties, and ethanol content was significantly correlated to fermen-tative strength. There were no significant correlation between AC and RVA eigenvalues, but pasting temperature (PT) was posi-tively correlated to dry matter content (r=0.661, P0.01) and starch content (r=0.670, P0.01). AC was positively correlated to ethanol content (r=0.653, P0.01) and fermentative strength (r=0.698, P0.01), but not significantly correlated to fermentation efficiency and fermented mash viscosity. Fermented mash viscosity was negatively correlated to breakdown value (BDV) (r= –0.563, P0.05) and positively correlated to setback value (SBV) (r=0.639, P0.05), but ethanol content, fermentation efficiency and fermentative strength were not significantly correlated to RVA eigenvalues. The cluster analysis showed that 15 varieties were divided into three parts: the first part featured higher AC and BDV, the second part had the highest AC and the lowest BDV, and the third part had the lowest AC and the highest BDV. Consequently, AC and BDV could be used as the indexes to evaluate the ethanol fermentation characteristics of sweetpotato, and the sweetpotato with higher AC and BDV was the breeding targets for fuel ethanol.