微波频率、含水率与无机盐对小麦胚芽介电特性的影响

Effect of Microwave Frequency,Water and Inorganic Salts on Dielectric Properties of Wheat Germ

为探明微波稳定麦胚的机制,以小麦胚芽为研究对象,研究了不同测量频率、含水率、脂肪含量及添加不同无机盐条件下麦胚粉体的介电特性(介电常数ε'和介电损耗因数ε″)。实验结果表明,在2个常用微波频率下,小麦胚芽ε'在频率为915 MHz时略大于2 450 MHz时,但ε″在2 450 MHz时明显大于915 MHz时;小麦胚芽介电特性随含水率的增加而增大,当其含水率从4%增至16%时,其ε'和ε″分别从2.61和0.02升高至4.32和0.8;不同脂肪含量的小麦胚芽的介电特性相差较小,尤其是ε″;对比添加5种无机盐后小麦胚芽介电特性发现,Na Cl对其ε'和ε″有明显增加作用,尤其是当Na Cl的质量分数为1%时,效果最明显。

Microwave can stabilize the quality of wheat germ rapidly and uniformly with the advantages of losing nutrition minimally. To investigate the mechanism of microwave on the stability of wheat germ,the dielectric properties（ ε＇ and ε″） of wheat germ were studied under different frequencies,water contents,fat contents and salts,including sodium,potassium,magnesium,calcium and iron ion. The results showed that,when the frequency was 915 MHz,ε＇ is slightly higher than that at 2 450 MHz,while ε″was less than that at 2 450 MHz significantly. When water content is 16%,with frequency changes from915 MHz to 2 450 MHz,ε＇ was decreased from 4. 91 to 4. 32,and ε″ was increased from 0. 33 to 0. 80.As water content of wheat germ increasing,the dielectric properties of wheat germ were increased significantly. When the water content was increased from 4% to 16%,the ε＇ was increased from 2. 61 to4. 32,and ε″ increased from 0. 02 and 0. 8,respectively. Fat content had little effect on the dielectric properties of wheat germ,particularly has no effect on ε″. Among the five salts,adding Na Cl can increase ε＇ and ε″ of wheat germ. Especially when Na Cl concentration was 1%,ε＇ was increased slightly while ε″ was increased apparently from 0. 8 to 1. 3,which can enhance enzyme inactivation effect of microwave.