加工精度和蒸煮条件对大米中镉的形态的影响

Effect of milling degree and cooking conditions on the form of cadmium in rice

将镉污染的稻谷碾磨成不同加工精度的大米(1级米、2级米、3级米、4级米和糙米),并选择1级、3级和糙米制备米饭/粥,观察大米表面形貌、测定蛋白质含量;分析大米及米饭/粥中总镉、无机镉含量及蛋白质的紫外吸收特征。结果显示:随着加工精度的增加,大米表面的糊粉层逐渐被除去,大米中总镉、无机镉和蛋白质含量均逐渐降低,蛋白质的紫外吸收峰高度略有降低;米饭/粥中总镉和无机镉含量明显降低,蛋白质紫外吸收峰的高度逐渐降低。这表明加工精度和蒸煮条件显著影响了大米和米饭/粥的总镉、无机镉含量,其中,加工精度是主要的因素,控制加工精度可以减少大米和米饭/粥的镉含量。

Cadmium-contaminated rice was milled into different milling degree(first-grade, second-grade, third-grade, fourth-grade, and brown rice), and first-grade, third-grade, and brown rice were selected to prepare rice/porridge. The surface morphology of rice was observed and the contents of total cadmium, inorganic cadmium, and protein of rice and rice/porridge were analyzed as well as the UV absorption characteristics of protein. The results showed that with an increase of milling degree, the aleurone layer on the surface of rice was gradually removed. The contents of total cadmium, inorganic cadmium, and protein in rice decreased gradually, and the contents of total cadmium and inorganic cadmium in rice/porridge decreased significantly, as well as the UV absorption peak height of the protein. These results indicate that the milling degree and cooking conditions significantly affect the total cadmium and inorganic cadmium contents of rice and rice/porridge, especially the milling degree. The cadmium contents of rice and rice/porridge could be reduced by controlling the milling degree.