Nonenzymic browning of cauliflower on storage.

The nonenzymic browning of cauliflower homogenate was evaluated during storage at temperatures ranging between 40 degrees and 80 degrees C. In these accelerated tests, the reflectometric measurement was more sensitive and more reliable than the measurement of colour intensity of ethanolic extracts. The browning followed the kinetics of a first order reaction at higher temperatures and that of a zero order reaction at lower temperatures. The activation energy depended considerably on the reaction temperature. The rate of browning was only slightly affected by the addition of ferrous ions both in the absence and in the presence of oxygen. Results of model experiments show that the most important reaction under experimental conditions was probably the reaction of free amino-acids and other amine derivatives with quinones produced by oxidation of natural polyphenolic compounds. Red primary condensation products were transformed into brown pigments by subsequent secondary reactions.