Spectrophotometric determination of volatile carbonyl compounds as a rapid method for detecting grain spoilage during storage

Abstract

A rapid and sensitive method is described for measuring the volatile carbonyl compounds in grain as an indicator of microbial infection. The method involves the spectrophotometric analysis of oximes formed by reaction of volatile carbonyl compounds with hydroxylamine hydrochloride as a stream of N 2 is passed through the grain and, subsequently, through the reagent solution. Using this procedure, the volatile carbonyl content of sound uninfected wheat and maize grain were determined as ranging from 0·07 to 0·22 mg of acetone equivalent/100 g of grain. The volatile carbonyl contents of wheat and maize increased rapidly during microbial growth. When samples of grain were inoculated with pure cultures, maximal levels of carbonyl compounds were 2·3 and 3·2 mg/100 g for wheat and maize, respectively, for bacterial cultures, and 2·0 and 2·4 mg/100 g, respectively, for mould cultures. It is suggested that the method could be adapted readily for monitoring microbial infection in commercial grain stores.