STRAWBERRY JUICE COLOR - THE EFFECT OF SULFUR-DIOXIDE AND EDTA ON THE STABILITY OF ANTHOCYANINS

The loss of anthocyanins and the formation of colour due to polymeric pigments in juices and purees prepared from strawberries (variety Senga sengana) was studied during storage at - 20-degrees-C and + 20-degrees-C. Four different treatments were given to the samples immediately after milling: no additions, EDTA addition, sulphur dioxide addition, and a combination of sulphur dioxide and EDTA. The concentration of anthocyanins and the proportion of colour due to polymeric pigments were measured by high-performance liquid chromatography and spectrophotometry. Losses in anthocyanins were very small during 10 weeks storage at - 20-degrees-C and there was no effect of the treatment. The addition of sulphur dioxide slowed down the loss of anthocyanins at + 20-degrees-C, especially in the purees, and correspondingly decreased the rate of polymeric pigment formation. Addition of EDTA had only a slight effect on colour stability.