湿热及酶解处理对糯米粉体外消化特性和血糖生成指数的影响

目的 研究酶解处理、湿热处理和湿热复合酶解处理对糯米粉体外消化特性和血糖生成指数(glycemic index, GI)的影响。方法 采用体外消化法测定了不同处理糯米粉的水解度和血糖生成指数值, 并通过X-射线衍射和激光共焦拉曼光谱实验测定了不同处理糯米的淀粉晶体结构。结果 3种处理的水解度和抗性淀粉(resistant starch, RS)相对含量增加, 慢消化淀粉(slowly digestible starch, SDS)相对含量降低; 其中湿热复合酶解处理条件下, RS相对含量最高, 为71.31%; 酶解处理条件下, RS相对含量最低, 为67.66%。酶解处理、湿热处理和湿热复合酶解处理的GI值分别为79.1、76.0和70.6。3种处理后糯米淀粉的晶体结构发生改变, 3种处理均使分子短程有序度与结晶度增加, 其中湿热复合酶解处理条件下, 结晶度最高, 为34.41%。 结论 湿热复合酶解处理后的糯米粉抗消化特性增强且GI值降低, 湿热复合酶解工艺可能通过影响糯米粉的体外消化率来降低GI值。

Effects of moisture heat with enzymatic hydrolysis treatment on digestion characteristics in vitro and glycemic index of glutinous rice flour

Objective To investigate the effects of enzymatic hydrolysis treatment, moisture heat treatment and moisture heat with enzymatic hydrolysis treatment on the in vitro digestion characteristics and glycemic index (GI) of glutinous rice powder. Methods The degree of hydrolysis and GI of different treated glutinous rice were measured by in vitro digestion, and the starch crystal structure of different treated glutinous rice was determined by X-ray diffraction and laser confocal Raman spectroscopy. Results The degree of hydrolysis and the relative content of resistant starch (RS) were increased, while the relative content of slowly digestible starch (SDS) decreased in three treated group. Under the condition of moisture heat with enzymatic hydrolysis treatment, the relative content of RS was the highest (71.31%), while under the condition of enzymatic hydrolysis treatment, the relative content of RS was the lowest (67.66%). The glycemic index (GI) values of enzymatic hydrolysis treatment, moisture heat treatment and moisture heat with enzymatic hydrolysis treatment were 79.1, 76.0 and 70.6 respectively. The crystal structure of glutinous rice starch was changed after the three treatments. The molecular short-range order and crystallinity of glutinous rice starch were increased by the three treatments, in which the crystallinity of glutinous rice starch was the highest (34.41%) under the condition of moisture heat with enzymatic hydrolysis treatment. Conclusion The anti-digestion characteristics of glutinous rice flour treated by moisture heat with enzymatic hydrolysis are enhanced and the GI value is reduced. The moisture heat with enzymatic hydrolysis process may reduce the GI value by affecting the in vitro digestibility of glutinous rice flour.