大米中营养元素分布及与加工精度的关系

Relationship between Nutrient Element Distribution and Processing Degree of Rice

以水稻龙粳40作为研究对象,依据GB/T 5502—2008《粮油检验:米类加工精度检验》染色法,加工得到不同等级大米,运用电感耦合等离子体质谱仪测定不同等级大米中17种营养元素的含量,并通过X射线光电子能谱仪对水稻籽粒颖果外表面、近表面、近中部和米中部的元素含量进行定量分析。结果表明,不同加工等级间大米中Na、Mg、K、Ca、Cr、Mn、Co、Cu、Zn、Rb和Sr的11种元素存在极显著差异(P<0.01),并且11种元素在不同等级间损失率不同;Na、K、Ca、Fe元素在水稻籽粒不同部位的含量有差异,颖果表面Na、K、Ca、Fe含量较高,近中部和米中部含量较低。各营养元素在稻谷中分布不均匀,在加工过程中,营养元素将不同程度地损失。

This study was performed to examine the distribution profiles of nutrient elements in rice. Rice grains of the cultivar Longjing 40 were processed to different grades according to the staining method in the Chinese national standard GB/T 5502—2008. A total of 17 kinds of nutrient elements in rice with different processing levels were determined by inductively coupled plasma mass spectrometry(ICP-MS) and quantitative analysis of the elements on the surface, near the surface, near the core, and in the core of rice caryopsis was conducted by X-ray photoelectron spectroscopy(XPS). The results showed that the contents of 11 kinds of elements including Na, Mg, Al, K, Ca, V, Cr, Mn, Fe, Co, Cu, Zn, Rb, Sr, Mo, Cs and Ba differed significantly in different grades of rice(P < 0.01), and their loss rates varied across grades. The contents of Na, K, Ca and Fe were different in different parts of rice grain, and their contents were higher on the surface than near the core and in the core of rice caryopsis. On the other hand, the distribution of nutrient elements in the caryopsis was not uniform, and rice processing may cause losses of the nutrient elements in different levels.