微波处理对米糠稳定性及脂肪酸组成的影响

采用微波加热技术对米糠进行稳定化处理。考察米糠水分含量、微波处理时间和微波功率对米糠中过氧化物酶残余相对活力的影响和储藏30 d后酸值变化情况，采用正交试验优化微波工艺参数，得到最佳工艺参数。结果表明：当料层厚度为1 cm时，米糠最佳微波处理工艺参数为：水分含量28%、微波时间90 s、微波功率600 W，微波处理后米糠中的过氧化物酶残余相对活力为1.9%，小于最大允许值5%，并在37 ℃的恒温培养箱中储藏30 d后，脂肪酸值为17.5 mg KOH/g，远小于空白组中212.0 mg KOH/g的脂肪酸值。同时，对微波稳定化处理前后的米糠进行气相色谱-质谱法分析，结果表明微波稳定化处理对米糠油中主要脂肪酸的组成影响较小。微波处理后可明显提高米糠稳定性，有利于米糠油的提取。

Effects of Microwave Treatment on Stability and Fatty Acid Composition of Rice Bran

Stabilized treatment was conducted on rice bran through microwave. The effects of the moisture content of rice
bran, microwave processing time and power on residual peroxidase activity of rice bran and acid value changes after 30 days
of　storage were examined. An orthogonal array experimental design was applied to optimize the microwave processing
parameters. The results indicated that when the thickness of the material layer was 1cm, the optimal microwave conditions
were as follows: moisture content, 28%; processing time, 90 seconds; and microwave power, 600 W. Under the optimal
conditions, the residual peroxidase activity was 1.9%, which was lower than the maximum permissible value of 5%. After 30
days of strorage at 37 ℃, the fatty acid value was 17.5 mg KOH/g, far lower than that of the control group (212.0 mg KOH/g).
At the same time, gas chromatography-mass spectrometry (GC-MS) analysis showed that microwave treatment had little
effect on the main fatty acids of rice bran. Therefore, microwave treatment can largely improve the stability of rice bran and
is available for the extraction of rice bran oil.