富硒糙米不同碾磨级分米糠蛋白的硒含量

Selenium Content and Functional Properties of Rice Bran Protein in Different Milling Fractions

摘要:

该研究通过分步碾磨将富硒糙米中的米糠分成五个级分，得到最外层（BF1）到最内层（BF5）的米糠和精米（MR6）原料，每一组分约占整个籽粒的2.2%（m/m）。对以上不同级分米糠及其蛋白中的硒元素分布、抗氧化活性和α-淀粉酶的抑制能力进行研究。结果表明，南粳9108、野香优航1573和巨2优60三种稻米富硒处理后糙米中硒含量分别为356.78、842.83和1 065.67 μg/kg，提高了7.89~23.54倍。糙米中的硒元素分布并不均匀，在BF3组分含量最高，此后随碾减率的增加逐步降低，精米中的含量最低。相同碾减率下，富硒米糠蛋白和富硒精米蛋白的DPPH·清除率、ABTS+·清除能力、·OH清除能力和铁离子还原能力均显著高于未富硒处理的普通对照组。同一品种中，在BF1~BF4级分米糠蛋白的抗氧化能力和α-淀粉酶的抑制能力最强，相较于精米蛋白，米糠蛋白均表现出更强的抗氧化活性（P<0.05）。富硒处理后，BF1、BF2、BF3和BF4组分米糠蛋白的α-淀粉酶的抑制能力显著高于普通米糠蛋白（P<0.05）。研究为富硒糙米适度加工及米糠的综合利用提供依据。

Abstract:

In this study, rice bran in Se-rich brown rice was divided into five stages by stepwise grinding. Rice bran and white rice (MR6) were obtained from the outermost layer (BF1) to the innermost layer (BF5). Each component accounted for approximately 2.2% (m/m) of the whole grain. Selenium distribution, antioxidant activity, and α-amylase inhibition in rice bran and different contents of its protein were studied. The selenium content in brown rice of ‘Nanjing 9108’, ‘Yexiang Youhang 1573’, and ‘Ju 2 You 60’ were 356.78, 842.83, and 1 065.67 μg/kg, respectively, which increased 7.89~23.54-fold. The distribution of selenium in brown rice was not uniform; the content of the BF3 component was the highest, and then gradually decreased with an increase in grinding rate. The content of selenium in milled rice was the lowest. At the same grinding rate, the DPPH· scavenging rate, ABTS+· scavenging capacity, ·OH scavenging capacity, and iron ion reducing capacity of selenium-enriched rice bran protein and selenium-enriched white rice protein were substantially higher than those of control group, which was not selenium-enriched. The antioxidant capacity and α-amylase inhibitory capacity of BF1–BF4 rice bran proteins were the strongest in the same cultivar, and rice bran proteins showed stronger antioxidant activity than mastic rice proteins (P<0.05). After selenium enrichment, α-amylase inhibition of BF1, BF2, BF3, and BF4 components of rice bran protein was substantially higher than that of common rice bran protein (P<0.05). This paper provides a basis for the moderate processing of selenium-rich brown rice and the comprehensive utilization of rice bran.