预酶解-挤压膨化对全谷物糙米粉品质特性的影响

以3 种糙米（普通糙米、红色糙米、黑色糙米）为原料，预酶解-挤压膨化制备实验组糙米粉，未经预酶解处理直接挤压膨化制备对照组糙米粉，分别测定其水溶性指数、吸水性指数、结块率、分散时间、米糊黏度、色度、糊化度、感官评分以及淀粉、还原糖、蛋白质含量等指标，并对淀粉和蛋白质进行体外模拟消化，比较并分析预酶解-挤压膨化对糙米粉品质特性的影响。结果表明：与直接挤压膨化相比，预酶解-挤压膨化处理使普通糙米、红色糙米、黑色糙米3 种糙米粉的水溶性指数分别提高了2.04、1.35 倍和1.71 倍；吸水性指数分别降低了67.87%、60.96%和62.17%；结块率分别提高了5.44、6.27 倍和3.07 倍；分散时间分别缩短了66.61%、61.79%和64.30%；米糊黏度降低，黏度曲线趋于平直，剪切稀释效应减弱；淀粉含量分别降低了29.22%、28.71%和26.70%，糊化度分别降低了19.53%、8.94%和13.13%；可溶性蛋白含量分别提高了1.50、2.87 倍和2.27 倍；差异均达显著水平（P＜0.05）。同时，亮度值略有升高，色差值分别为3.01、4.66、3.28；快消化淀粉比例降低，慢消化淀粉和抗性淀粉比例升高；蛋白质体外消化速率加快，消化率升高；综合感官评分显著升高（P＜0.05）。实验结果表明预酶解-挤压膨化处理提高了糙米粉的冲调分散性、降低了米糊黏度，提高了感官评分和蛋白质体外消化性能，对糙米粉品质具有提升作用。为拓宽糙米的加工利用途径、促进预酶解-挤压膨化技术在谷物加工领域中的应用提供了理论指导。

Combined Effect of Enzymatic Pretreatment and Extrusion on Quality Properties of Brown Rice Flour

To investigate the combined effect of enzymatic pretreatment and extrusion on the quality characteristics of brown rice flour, extruded brown rice flours with and without enzymatic pretreatment (control) from ordinary, red and black brown rice were examined for water solubility index, water absorption index, agglomeration rate, dispersion time, paste viscosity, color, gelatinization degree, sensory evaluation score, starch, reducing sugar and protein contents, and in vitro starch and protein digestibility. The results showed that compared with direct extrusion, enzymatic pretreatment combined with extrusion increased the water solubility index of ordinary, red and black brown rice flours by 3.04, 2.35 and 2.71 times, decreased the water absorption index by 67.87%, 60.96% and 62.17%, elevated the agglomeration rate by 6.44, 7.27 and 4.07 times, and reduced the dispersion time by 66.61%, 61.79% and 64.30%, respectively. Moreover the combined treatment decreased the viscosity of brown rice paste and weakened the shear-thinning behavior and the viscosity curves were more flat with it. The combined treatment reduced the starch content of ordinary, red and black brown rice flours by 29.22%, 28.71% and 26.70%, and the gelatinization degree by 19.53%, 8.94% and 13.13%; and increased the soluble protein content by 2.50, 3.87 and 3.27 times, respectively. All of these changes were statistically significant (P < 0.05). The color difference (ΔE) values of extruded ordinary, red and black brown rice flours with enzymatic pretreatment were 3.01, 4.66 and 3.28, respectively The combined treatment augmented slightly lightness value, reduced the percentage of rapidly digestible starch, increased the percentage of slowly digestible and resistant starch, enhanced the in vitro digestion rate and digestibility of protein, and resulted in significantly higher sensory evaluation scores (P < 0.05). The above data demonstrated that combined enzymatic pretreatment and extrusion improved the dispersibility of brown rice flour, reduced the paste viscosity, and increased sensory evaluation scores and protein digestibility in vitro. In conclusion, enzymatic pretreatment combined with extrusion can be viewed as a new approach for the processing and utilization of brown rice and has potential for application in cereal processing.