黄原胶和瓜尔豆胶对小麦淀粉冻融稳定性的影响

Effects of Xanthan Gum and Guar Gum on the Freeze-thaw Stability of Wheat Starch

将小麦淀粉分别与黄原胶和瓜尔豆胶以一定的比例复配,利用析水率实验、DSC方法和SEM微观结构观察等方法,研究亲水胶体黄原胶和瓜尔豆胶在5次冻融循环过程中对小麦淀粉稳定性的影响。研究结果表明:小麦淀粉的析水率随着循环次数的增加而增加,黄原胶和瓜尔豆胶能够明显降低冻融过程中小麦淀粉的析水率,从而抑制小麦淀粉冻融过程中的老化,且随着亲水胶体浓度的增加,对冻融稳定性的改善作用越强;小麦淀粉经过5次冻融循环后,淀粉胶基形成了大量的孔洞,并产生不连续丝状的,类似纤维的结构,且基质较薄,添加亲水胶体后显著改变了小麦淀粉的表观形态,孔洞明显减少,且淀粉基质增厚,形成了类似片状的网络结构。因此,黄原胶和瓜尔豆胶均能在一定程度上改善小麦淀粉的冻融稳定性,且与添加浓度有关。

Wheat starch was mixed with xanthan gum and guar gum at different mixing ratios, and detection of water syneresis rate, differential scanning calorimetry（DSC）, and scanning electron microscopy（SEM） were performed to study the effects of hydrocolloids（xanthan gum and guar gum） on the freeze-thaw stability of wheat starch after five freeze-thaw cycles. The results showed that the water syneresis rate of the wheat starch was enhanced with increasing freeze-thaw cycle number; xanthan gum and guar gum significantly decreased the water syneresis rate, thus inhibiting wheat starch aging during the freeze-thaw process. Additionally, the improvements in freeze-thaw stability were more significant with increasing hydrocolloid concentrations. After five wheat starch freeze-thaw cycles, a large number of holes were formed in the starch gum matrix, and some discontinuous silk- and fiber-like structures were formed, with a thin substrate. With the addition of hydrocolloids, the apparent structure of wheat starch changed： the number of holes decreased, the starch substrate was thickened, and a sheet-like network structure was formed. Therefore, both xanthan gum and guar gum can improve the freeze-thaw stability of wheat starch and the improvements from via hydrocolloids addition are concentration-dependent.