College of Food Science and Engineering, Northwest A&F University, Yangling 712100, China.
College of Food Science and Engineering, Northwest A&F University, Yangling 712100, China.
Int J Biol Macromol. 2019 Jul 15;133:346-353. doi: 10.1016/j.ijbiomac.2019.04.111. Epub 2019 Apr 16.
The study was undertaken to reveal the effects of freeze-thaw cycles at different freeze temperature (-20 °C, -40 °C and -80 °C) and the number of freeze-thaw cycles (3, 6, 12, 18, 24 times) on physicochemical and structural properties of waxy corn starch. The number of pores on the surface of starch granules increased, but there was no significant (P < 0.05) effect on molecular weight, transparency, freeze-thaw stability and the crystal structure of starch after repeated freeze-thaw cycle. But the crystallinity intensity decreased after freeze-thaw cycles treatment and a tiny decrease in onset, peak, conclusion temperature and gelatinization enthalpy were found. The RVA analysis exhibited an increase in gelatinization temperatures and a decrease in breakdown and setback value after freeze-thaw treatment, which manifested an increase in the aging and heat resistance of waxy corn starch paste. However, there was no statistical (P < 0.05) difference between different freeze temperatures at the same number of freeze-thaw cycle on physicochemical and structural properties of starch. The obtained data could be helpful in evaluation of the repeated freeze-thaw treatment of waxy corn starch-based foodstuffs and providing the theoretical basic for revealing the effect of repeated freeze-thaw processes in manufacture applications.
本研究旨在揭示不同冻结温度（-20°C、-40°C 和-80°C）和冻结-解冻循环次数（3、6、12、18、24 次）对糯玉米淀粉理化和结构特性的影响。淀粉颗粒表面的孔隙数量增加，但在经过多次冻融循环后，对分子量、透明度、冻融稳定性和淀粉晶体结构没有显著影响（P < 0.05）。然而，冻融循环处理后结晶度强度降低，起始温度、峰值温度、结束温度和凝胶化焓略有降低。RVA 分析表明，冻融处理后淀粉糊的凝胶化温度升高，崩解值和回生值降低，表明糯玉米淀粉糊的老化和耐热性增强。然而，在相同的冻融循环次数下，不同冻结温度对淀粉的理化和结构特性没有统计学差异（P < 0.05）。所得数据有助于评价基于糯玉米淀粉的食品的反复冻融处理，并为揭示在制造应用中反复冻融过程的影响提供理论基础。
