甘薯淀粉磷酸双酯消化特性研究

The Digestibility in Vitro of Sweet Potato Starch Phosphodiester

以三偏磷酸钠为酯化剂制备甘薯淀粉磷酸双酯。采用体外消化方法,模拟人体肠道体系,以玉米淀粉和甘薯淀粉为参照,对甘薯淀粉磷酸双酯的淀粉消化性能、体外消化速率进行研究,并根据淀粉水解百分率推算其血糖指数的变化。结果表明:甘薯淀粉经三偏磷酸钠酯化交联后,其红外光谱在1 033 cm-1处出现新的吸收峰,说明分子中引入了磷酸根基团。甘薯淀粉磷酸双酯和玉米淀粉、甘薯淀粉相比,其可消化淀粉含量大幅度减少,而抗消化淀粉含量显著上升。甘薯淀粉磷酸双酯的淀粉水解速率低于玉米淀粉和甘薯淀粉,说明甘薯淀粉磷酸双酯的消化吸收要慢于玉米淀粉和甘薯淀粉,其消化能力有较大水平的降低。玉米淀粉和甘薯淀粉预测血糖指数均在100以上,均为高血糖指数食品,甘薯淀粉磷酸双酯预测血糖指数为66.31,为中等血糖指数食品,可以添加在食品中为糖尿病患者食用。为进一步研究甘薯淀粉磷酸双酯的开发应用提供了一定理论依据。

Sweet potato starch phosphodiester was prepared by sodium trimetaphosphate. The digestibility in vitro of sweet potato starch phosphodiester was studied by a method in vitro simulating human intestinal system with the comparison of corn starch and sweet potato starch. Glycemic index （GI） was conjectured according to the percentage of starch hydrolysis. The results showed that the phosphate groups were incorporated into the molecular structure indicated by the FTIR spectrum which showed new absorption peaks at 1 033 cm1. The contents of digestible starches reduced apparently, and the resistant starch of sweet potato starch phosphodiester went up significantly. The hydrolysis rates of sweet potato starch phosphodiester were lower than for corn starch and sweet potato starch, indicating that sweet potato starch phosphodiester exhibited a slower absorption than com starch and sweet potato starch, the digestibility of sweet potato starch phosphodiester significantly decreased. Glycemic index of corn starch and sweet potato starch was greater than 100, which belonged to high GI foods. The predicated GI of sweet potato starch phosphodiester was 66.31, which belonged to middle GI foods, and was appropriate for the diabetes food. The results were useful for utilization of sweet potato starch phosphodiester.