麦胚多肽-钙螯合物制备工艺优化及其结构表征

Optimized Preparation and Structural Characterization of Calcium-Chelating Polypeptides from Wheat Germ Protein Hydrolysate

为减少小麦胚芽的资源浪费,提高其附加值,同时解决居民缺钙的问题,对麦胚多肽与钙离子螯合的工艺进行研究。以小麦胚芽为原料,以螯合率为考察指标,设计单因素试验和正交试验,考察温度、麦胚多肽与钙离子物质的量比、时间、pH值对螯合率影响。结果表明,在温度65℃、麦胚多肽与钙离子物质的量比3∶1、时间60 min、pH 9.5的条件下,螯合率达到最大,为86.21%。对最佳条件下制备的麦胚多肽-钙螯合物进行结构分析,红外光谱表明麦胚多肽的氨基和羧基都参与了螯合反应;圆二色谱表明螯合物的二级结构由原来的无序结构向有序、紧密的结构转变;扫描电子显微镜表明螯合物的分子有明显的聚集现象。

This study aimed to reduce the waste of wheat germ resource and simultaneously achieve its value-added utilization for the purpose of solving the problem of calcium deficiency in some populations. Wheat germ protein hydrolysates was prepared by enzymatic hydrolysis using alkaline protease and then chelated with calcium ions to obtain calcium-chelating polypeptides. One-factor-at-a-time and orthogonal array experiments were devised to investigate the influence of reaction temperature, molar ratio between polypeptides and calcium ions, reaction time and pH on the chelation efficiency. The optimal conditions that provided maximum chelation efficiency （86.21%） were determined as follows： reaction at 65 °C and pH 9.5 for 60 min with a molar ratio of polypeptide to calcium of 3：1. Infrared spectroscopic analysis confirmed the coordination reaction between calcium and carboxyl/amino groups in the polypeptides. Circular dichroism spectra indicated that the calcium-chelating polypeptides lost their disordered secondary structure and formed compact and ordered conformations compared to the control group. Scanning electron microscopy observation confirmed significant aggregation of calcium-chelating polypeptides.