植物油的介电常数及其品质变化之间的相关性研究
Correlation research between dielectric constant and the quality variation for vegetable oil
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摘要: 为了考察植物油介电常数的变化规律,本研究采用同轴探针技术,探究了25℃温度条件下菜籽油、调和油、葵花籽油、橄榄油、玉米油、芝麻油、大豆油及花生油等八种常见食用植物油的介电常数和脂肪酸组成。同时,测定了大豆油在油炸过程中酸值、过氧化值等品质变化,与介电常数的变化规律相联系起来,研究了两者之间的相关性。结果表明:在较低频段(100~180MHz)时,除花生油外,同频率下各种食用植物油介电常数大小与油中不饱和脂肪酸总含量呈正相关关系;在较高频段(300~10000MHz)内,油的介电常数随亚油酸含量的增加而增加。随着油炸时间的增加,大豆油的酸值逐渐增加,过氧化值先增加后减小,大豆油的介电常数逐渐增加。在同一频率下,大豆油的介电常数变化与上述品质变化呈正相关关系。Abstract: In order to investigate the changing rule of dielectric constant,the dielectric constant of colza oil,blend oil,sunflower oil,olive oil,corn oil,sesame oil,soybean oil and peanut oil were studied by the open-ended coaxial probe technology at 25℃. And the compositions of the fatty acid were measured. The change of acid value and peroxide value for soybean oil were been measured during frying,and connected to the changing rule of dielectric constant. The results indicated that at lower frequencies( 100 ~ 180MHz),the positive relationship was between dielectric constant and unsaturated fatty acid except for peanut oil; at higher frequencies( 300 ~ 10000MHz),dielectric constant of soybean oil was increasing with the content of linoleic acid.The acid value of soybean oil was increasing with the frying time,but peroxide value was increasing and then decreasing during frying.The dielectric constant was increasing during frying.At the same frequency,the positive relationship between dielectric constant and quality variation were found in this study.
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