碾轧处理对乙酰化淀粉品质的影响及作用机理

为研究碾轧处理对乙酰化淀粉品质的影响及其作用机理,本文以甘薯淀粉为原料,研究不同碾轧处理时间(0、2、5、7、18 h)对乙酰化甘薯淀粉的品质、结构和理化性质的影响,采用机械力化学相关理论分析碾轧处理对乙酰化甘薯淀粉品质影响的作用机理。结果表明:碾轧处理2和7 h后,乙酰化甘薯淀粉的反应效率分别增加到74.45%和75.40%,其它品质(溶解度、膨胀力和峰值黏度)也显著提高。甘薯淀粉在碾轧处理2 h后,与原淀粉相比,结晶度降低且位于17.8 °处的衍射峰消失,T₂值增大,糊化焓和峰值黏度减小,热稳定性减弱;碾轧处理5 h后,溶解度、膨胀力和峰值黏度都减小,但淀粉的热稳定性增大;与处理2 h后相比,结晶度变大,T_2,2值消失;碾轧处理7~18 h后,结晶度、糊化焓和热稳定性显著降低,T_2,1值增大,碾轧处理18 h后淀粉分子晶体区域的双螺旋结构呈短程有序方式排列。这些变化表明碾轧处理可对甘薯淀粉颗粒产生显著的机械力化学效应。随着碾轧处理时间的增加,淀粉颗粒内部依次经历了受力、聚集和团聚阶段。机械力化学对淀粉颗粒作用的三个阶段具有不同的影响机制,为今后研究制备高品质变性淀粉先进装备奠定一定的理论基础。

Effect of Rolling Treatment on Quality of Acetylated Starch and Its Mechanism

To investigate the effect and mechanism of rolling treatment on quality of acetylated starch, the different rolling treatment time (0, 2, 5, 7, 18 h) on acetylated sweet potato starch quality, structures and physicochemical properties of acetylated starch were studied with sweet potato starch as raw material. The mechanism of rolling on the quality of acetylated starch was analyzed according to the related theories of mechanochemistry. The results indicated that, after rolling for 2 h and 7 h, the reaction efficiency increased to 74.45% (2 h) and 75.40% (7 h) respectively, and other qualities (solubility, swelling power and peak viscosity) of acetylated starch increased prominently. After 2 h of rolling processing, compared with native starch, the crystallinity reduced and the diffraction peak at 17.8° level disappeared, the T₂ value increased, gelatinization enthalpy and peak viscosity decreased, and thermal stability weakened. After 5 h of rolling processing, the solubility, swelling power and peak viscosity were all declined, while the thermal stability of starch increased. Compared with that of 2 h of rolling handling, the crystallinity with 5 h treatment increased, value of T_{2, 2} disappeared. After 7~18 h of rolling processing, the crystallinity, gelatinization enthalpy and thermal stability significantly declined, while the value of T_{2, 1} increased. After rolling treatment for 18 h, the double helix structure in crystalline region was arranged in a short-range orderly manner. These changes indicated that rolling had a significant mechanochemistry effect on sweet potato starch granules. With the increase of rolling time, the interior of starch granules gradually experienced the stress, aggregation and agglomeration stages consecutively. Three stages of mechanochemistry effect of starch varied in terms of influence mechanisms, which laid a theoretical foundation for the advanced equipment of preparing high performance modified starch in the future.