淀粉球晶的制备及其理化性质

Preparation and Physicochemical Properties of Starch Spherulites

本文以蜡质玉米淀粉为试验原料,采用酶法脱支淀粉后重结晶制备淀粉球晶,通过对所制淀粉球晶的链长分布与分支度、回收率、球晶形貌特征、结晶度分析及热力学性质测定,考察异淀粉酶添加量和结晶时间对球晶理化性质的影响。结果表明:淀粉糊化后冷却至50℃加入25 U/g异淀粉酶反应24 h可使支链淀粉完全脱支,所得淀粉球晶平均链长为26.70;已脱支的淀粉于25℃条件下重结晶,回收率和结晶度随着结晶时间的延长而提高,结晶24 h回收率和结晶度分别为76.58%和51.1%;淀粉球晶的起糊温度(T_o)、峰值温度(T_p)、终止温度(T_c)和焓值(△H)高于原淀粉,且随着结晶时间的延长而呈现增大趋势;SEM图像显示,随着结晶时间的延长,淀粉球晶的颗粒度逐渐清晰,但淀粉球晶颗粒出现聚集现象。

In this study, waxy maize starch was used as the experimental raw material, and starch spherulites were prepared via isoamylase-catalyzed debranching and recrystallization. The effects of enzyme quantity and recrystallization time on the properties of starch spherulites were investigated though measuring the chain length distribution, branching degree, yield, morphology, crystallinity and thermodynamic properties. Results showed that the gelatinized waxy maize starch could be completely debranched by isoamylase(25 U/g) through adding the enzyme after being cooled to 50 ℃ followed by an incubation at 50 ℃ for 24 h. The average chain length of the obtained starch spherulites was 26.70. The debranched starch was recrystallized at 25 ℃ to form starch spherulites. The yield and crystallinity of starch spherulites increased with the crystallization time, which were 76.58% and 51.1%, respectively, after crystallization for 24 h. The onset gelatinization temperature(T_o), peak temperature(T_p), conclusion temperature(T_c) and enthalpy change( H) of starch spherulites were higher than those for the original waxy maize starch, and these values increased with the crystallization time. The SEM images showed that the granules of starch spherulites and agglomeration of starch granules became obvious with the increase of crystallization time.