A Simple Method for Determining the Carbonyl Value of Volatile Carbonyl Compounds. IV.

Abstract

A Simple and rapid method was developed for measuring the degree of rancidity in food fat. The new method is based on using heptane to extract the oil in foods, instead of benzene in previously proposed “benzene distillation method”. The recoveries of carbonyl compounds especially C6 aldehyde with “heptane distillation method” were satisfactory for this purpose. The developments of rancidity in fried rice crackers were measured by sensory evaluation and chemical tests such as the measurement of peroxide value (POV) and volatile carbonyl value (VCV) with heptane distillation method. The results showed a good correlation between the VCV and flavor score when POV and VCV were increasing. In the stage when POV or VCV were decreasing, no correlation or a reverse correlation was found between flavor score and VCV. This was infered to be caused by the oxidation of aldehydes to acids. Comparing Figs. -4 and 5, mixing of spices such as curry powder to foods was apt to mislead the judgment on the flavor score of autoxidized oils in fried rice crackers.