商用白色玉米朊的性质分析及其质量评价

Evaluation of Properties and Quality of Commercial White Zein Products

摘要:

为弥补我国白色玉米朊产品生产企业及使用单位无检验标准可依的不足，本研究采用化学分析与仪器分析的方法，对商用白色玉米朊的化学组成、重金属含量、色素含量、溶解性，分子量分布和蛋白质结构进行了全面的质量评价。结果表明，白色玉米朊产品中蛋白质与重金属含量均满足国家药典标准。色素含量仅为黄色玉米朊的22.18%，且无明显变性现象。相比黄色玉米朊，白色玉米朊产品分子量与之相近，但二级结构中的α-螺旋含量由56.37%上升至60.42%，β-折叠含量由10.51%降低至5.92%，三级结构则无明显变化。造成以上结果的原因主要是，脱色处理使白色玉米朊产品中的β-玉米朊、色素和变性蛋白含量降低，α-玉米朊含量显著提高。因此，白色玉米朊的生产企业和使用单位可根据实际情况，建立多层次的白色玉米朊质量评价体系。而本研究为玉米朊相关的理论研究提供了参考。

Abstract:

In order to fill the gap in thinspection standards for the production and application of white zein products in China, this research evaluated comprehensively the quality of commercial white zein via chemically and instrumentally analyzing the chemical composition, heavy metal content, pigment content, zein solubility, molecular weight distribution and protein structure. The results showed that the contents of protein and heavy metals in the white zein met the requirements of the Chinese Pharmacopoeia and National Standards. The pigment content of white zein was only 22.18% of that of yellow zein, and there was no obvious denaturation in white zein. Compared with yellow zein, the white zein had a similar molecular weight and tertiary structure but altered secondary structure (α-helix content, increased from 56.37% to 60.42%; β-sheet content, decreased from 10.51% to 5.92%). These results were mainly due to the decolorization treatment which had reduced the contents of β-zein, pigment and denatured protein whilst increased the content of α-zein. Therefore, a multi-level quality evaluation system should be established by manufacturers and users according to the actual conditions. This study provides a reference for theoretical research related to zein.