本文以玉米、木薯、马铃薯、西米四种淀粉为原料，采用100~200 ℃高温加热的方式，研究原淀粉以及经物理方法处理后的淀粉白度在高温下变化情况，并用扫描电镜观察白度变化最明显的马铃薯淀粉颗粒形貌。结果表明，经过200 ℃加热，马铃薯原淀粉白度从85.88降到45.51，变化最明显，玉米原淀粉白度从88.21降到79.10，变化最小；原淀粉经乙醇提纯后加热，以及原淀粉在真空下加热，白度变化趋势跟原淀粉差不多，且200 ℃下白度都比原淀粉同温下白度下降2~6，其中马铃薯淀粉白度变化最明显；原淀粉分别在酸、碱性条件下加热，白度变化更明显，特别是碱性条件下，此时200 ℃下，白度都降到13.67~24.76；原淀粉经过预糊化后高温加热，不同淀粉白度变化大致相似，且200 ℃下白度都非常接近39。说明淀粉中蛋白质和脂质对高温下淀粉白度影响不大，不同淀粉白度耐高温特性的差异可能与淀粉颗粒大小有关。

Using corn, cassava, potato, and sago starches as raw materials, high temperature treatment from 100 to 200 ℃ was adopted to investigate changes in the whiteness of original starches and starches treated with physical methods. Scanning electron microscopy (SEM) was used to observe the granular morphology of potato starch, which had the most obvious change in whiteness. Results showed that, after heating at 200 ℃, the whiteness of potato starch decreased from 85.88 to 45.51, which was the largest change; corn starch whiteness reduced from 88.21 to 79.10, which was the smallest change. After purification by ethanol, the resultant and original starches showed similar changes in whiteness under vacuum heating. At 200 ℃, the largest change in whiteness occurred in potato starch and the whiteness of all starches was lowered by 2 to 6 compared to their respective original starches. After heating under acidic or alkaline conditions, changes in whiteness were more obvious in the native starches, especially under alkaline condition. After heating at 200 ℃, whiteness was reduced to a range of 13.67 to 24.76. When starches were pre-gelatinized and heated, the changes in whiteness were roughly the same for the different starches; whiteness was very close to 39 at 200 ℃. These results demonstrate that the proteins and lipids in starch have little influence on the changes in its whiteness; however, variation in the thermostability of the whiteness of different starches might be related to their granular sizes.

广东省国际合作项目（2011B050800004）