Studies on Foaming of Mixed Edible Oil with Coconut Oil under Deep-fat Frying

点击翻译按钮获取中文摘要

1. Cococut and palm kernel oils belong to the lauric oil and are commercially important. The disadvantages of this type oil are that admixture of the oils with other frying oils, e.g., soybean oil, produces a characteristic foaming under deep fat frying. In the present study, the foaming activity of the mixed oil between lauric and nonlauric oils was investigated in detail.The foaming properties of the mixed oils decreased remarkably after random interesterification, when the intermediate carbon number triacylglycerols increased, while the fatty acid compositions of the oils were remained unchanged. Similar effects of interesterification were found in a model system of mixtures of monoacid triacylglycerols. It was discussed that the characteristic foaming arose from the disparity of triacylglycerol molecular size, but not from that of fatty acid composition.2. The influence of interesterification on the thermal oxidation stability of mixed oils during continuous heating at high temperature was investigated, using soybean, palm and coconut oils whose fatty acid compositions differ each other. The extent of thermal deterioration in each oil increased in proportion to the degree of unsaturation, and nearly no difference between the mixed oils and their interesterified oils. However, the refractive index of the interesterified oil increased more rapid than the others. It was supposed that the rapid increase might be caused by increasing of triacylglycerol molecular species which were easily polymerized.