烘焙和喷雾干燥对紫米粉特性和结构的影响

Effects of Roasting and Spray Drying on Properties and Structures of Purple Rice Flour

研究烘焙和喷雾干燥处理对紫米粉色泽、糊化及热特性的影响。结果表明:烘焙尽管对样品的短程有序结构及蛋白质二级结构影响不显著,但由于引起淀粉颗粒部分凝胶化及膨化,样品的结晶度及峰值黏度、最终黏度、崩解值、回生值等糊化相关黏度参数和热焓值均降低,而糊化温度升高;喷雾干燥不仅降低了样品的结晶度和粒径,也引起蛋白质部分α-螺旋和β-折叠结构转变β-转角结构,进而使样品的峰值黏度、谷值黏度、最终黏度、峰值时间及糊化温度均略有升高,而崩解值和回生值及热焓值略有降低;烘焙处理紫米粉的色泽较暗淡,而喷雾干燥样品的色泽更鲜亮。总之,2种热处理方式尽管均引起紫米粉中淀粉发生部分凝胶化,但对样品的色泽和物化特性的影响效果明显不同。

The effects of roasting and spray drying on colour,pasting and thermal properties of purple rice flour were studied.The results showed that roasting had no significant effect on the short-range ordered structure of starch and the secondary structure of protein,but caused samples to partially gelatinize and puff,which decreased the crystallinity,peak viscosity,final viscosity,other viscosity parameters and the enthalpy of purple rice flour.Spray drying not only reduced the crystallinity and particle size of the samples,but also transformed the α-helix and β-sheet into the β-turn,which increased peak viscosity,final viscosity,valley viscosity,peak time and pasting temperature,but decreased the enthalpy and setback and breakdown of purple rice flour.Compared to the control,the color of roasted purple rice powder was darker,while the color of spray-dried samples was brighter.Overall,although the two heat treatments both caused partial gelation of the samples,the color and physicochemical properties of the treated samples were obviously different.