稻谷水热加工过程中镉迁移规律研究

目的研究稻谷在蒸谷米水热加工过程中镉的迁移规律。方法以蒸谷米小试装置及生产线采集样品为研究对象,在优化碾米时间的基础上,在排除水分含量差异对测定结果的前提下,利用统计分析考察水热工艺(浸泡和蒸煮)对稻谷各部分(稻壳、米糠和精米)镉含量的影响。结果由实验数据推断,在水热过程中,镉的迁移主要发生在稻谷的内部,且主要是在浸泡时从精米向米糠迁移富集,而蒸煮工艺则对镉的分布变化影响很小;经过浸泡,精米中的镉含量可降低约40%;推测热水的浸泡一方面使胚乳淀粉分子间游离的镉部分溶出,一方面促使镉向络合能力更强的米糠蛋白迁移,最终导致其分布发生明显变化。结论该研究为在稻谷加工过程中实现重金属镉的消减提供了科学依据。

Cadmium migration in rice grain through hydrothermal processing

Objective To study the migration rule of cadmium in rice grain during parboiling process. Methods Based on the optimizing milling time and ruling out the influence on the testing results of different moisture content in rice grain, the influence of hydrothermal processing (soaking and steaming) on cadmium concentration in husk, bran and milled rice samples were statistically investigated from both lab-scale and industrial production line of parboiled rice. Results The migration of cadmium mainly occurred inside rice grain and mostly from milled rice to bran during soaking of parboiling process, while steaming had low impact on the distribution change of cadmium. The concentration of cadmium in milled rice exhibited a distinct decrease around 40%. It was inferred that the soaking of hot water partially dissolved free cadmium from starch molecules in endosperm, and facilitated the migration of cadmium to bran proteins which possessed stronger complexing ability. Conclusion This study provides scientific basis for the reduction of cadmium through rice processing.