Chlorophyll, colour and pH changes in H.T.S.T. processed green pea puree

Abstract
Summary. Pea puree of pH 6.95 and pH 8.45 was heat processed in thermal death‐time tubes at temperatures between 115.6°C and 148.9°C to a process value of F0= 6.0. Chlorophyll pigments, Hunterlab colour indices and pH were determined before and after high temperature‐short time (H.T.S.T.) processing and during storage for 18 months at 20°C, 2.8°C, and −23.3°C.Highly significant correlations were found between per cent conversion of chlorophylls to pheophytins and objective colour indices derived from tristimulus measurements on stored pea puree. the degree of chlorophyll conversion, and hence puree colour, were both markedly affected by process temperature, product pH, storage time and storage temperature, but long‐term storage stability was achieved only by combinations of two or more variables.Changes in pH of processed and stored puree were directly related to changes in pigments and colour, and it appears that pH control during processing and storage offers the most likely means of colour and pigment retention in heat processed chlorophyll‐containing foods.