揮発性カルボニル化合物のカルボニル価の簡易測定法(第1報)

揮発性カルボニル化合物のカルボニル価の簡易測定法の提案とその検討

抄録

A simple and rapid method was developed for measuring the degree of rancidity in food fat. At first, the oil-bearing food was immersed in benzene, and the oil in the food was extracted. During this extraction, volatile carbonyl compounds moved to the solvent. A part of the benzene extract was transfered to a distillation apparatus. Then, the solvent was distilled off. Most of volatile carbonyl compounds from the food fat were also evaporated with benzene and collected in the distillate. The amount of carbonyl compounds condensed in the distillate was determined by converting the carbonyls into their 2, 4-dinitrophenylhydrazones and then measuring the absorbance of the wine-red color of quinoidal ions. In this report, this procedure was applied to aged fried rice crackers as follows. The rice crackers were fried with soybean oil, corn oil, and lard at 240°C as well as with these oils that had been heated at 240°C for 2 h. Then, these fried rice crackers were aged under various conditions, such as in dark at 35°C and 62°C, and in light at 25°C. The development of rancidity in these fried rice crackers was measured by sensory evaluation by an experienced panel and chemical tests such as the measurement of peroxide value, carbonyl value, and this carbonyl value of volatile carbonyl compounds. The results showed the best correlation between the volatile carbonyl values and flavor score. The merit of volatile carbonyl value of volatile carbonyl compounds for measuring the degree of rancidity was discussed.