STRAWBERRY JUICE COLOR - THE EFFECT OF SOME PROCESSING VARIABLES ON THE STABILITY OF ANTHOCYANINS

The colour stability of juice and purees made from a mixture of two strawberry varieties, stored at + 20-degrees-C or at - 20-degrees-C under aerobic and anaerobic conditions, was studied. High-performance liquid chromatography and spectrophotometric analysis were used to monitor the changes in colour during storage. Pelargonidin 3-glucoside comprised 80 % of the total anthocyanin content. Four other pelargonidin-based peaks were found, being 10.4 %, 3-5 %, 0.7 % and 0-3 % of the total and two cyanidin peaks were present, being 3.3 % and 0.4 % of the total. Clarification before storage caused considerable losses in the initial anthocyanin concentrations. Storage conditions (air versus nitrogen) did not influence the rate of loss of anthocyanins during storage or the formation of polymeric pigments. There were no losses in anthocyanins and no increase in the amount of colour measured at 510 nm due to polymers in samples stored at - 20-degrees-C. Polymerisation occurred in the samples stored at + 20-degrees-C , especially in the clarified samples.