低温冻融处理对糯性玉米淀粉颗粒结构特性的影响

Effects of low temperature freeze-thawing on the structural characteristics of waxy corn starch granule

以糯性玉米淀粉为原料,采用低温缓慢冻融和液氮快速冻融方法分别处理糯性玉米淀粉,通过扫描电镜、偏光显微镜、粒度仪和X射线等仪器测定分析了冻融处理前后糯性玉米淀粉颗粒形貌、颗粒大小及粒径、偏光性及结晶性的变化情况。实验结果表明:随着反复冻融次数增加,糯性玉米淀粉颗粒表面微孔数目增多、微孔变大、颗粒大小及平均粒径减小、偏光十字减弱,而且低温缓慢冻融对淀粉颗粒结构特性改变更为显著,反复20次冻融会造成淀粉颗粒结构显著破坏;但冻融温度和冻融次数对淀粉颗粒结晶类型和结晶衍射峰强度影响不大。因此,低温缓慢冻融方法可应用于淀粉物理改性领域,通过控制冻融次数和冻融温度可有效改变淀粉颗粒结构特性变化及改性程度。

The waxy corn starch were processed by slowly and rapidly freeze-thawing methods, and the granule morphology, particle size, mean diameter, polarization cross and crystallinity properties of waxy corn starch were investigated by scanning electron microscopy, polarized light microscope and X-ray diffraction. Results showed that the micro-pores increased, particle size and mean diameter decreased, polarization cross weakened, moreover, the slowly freeze-thawing could significantly change the granule structure properties, and more than 20 times freeze-thawing cycles could destroy the granule structure. However, freeze-thawing temperature and cycle times have little effects on the crystallinity patterns and intensity. Therefore, the slowly freeze-thawing method could apply in starch modification, we can change the starch granule structure and modification degree by controlling the freeze-thawing temperature and cycle times.