Stability of anthocyanins in berry juices stored at different temperatures

The bright purple-red colour caused by anthocyanins is characteristic of berry products. The colour becomes easily distorted as anthocyanins are susceptible to various degradation reactions. In this study, we monitored the stability of structurally different anthocyanins in several berry juices during storage at different temperatures. The anthocyanin stability was found to be affected by a number of factors including the type of anthocyanin, the origin of the juice, and especially the storage temperature. In all studied juices, half-life (t½) of anthocyanins was much shorter at room temperature than at cold storage. Anthocyanins were more stable in chokeberry juice (t½ = 6.7 weeks at 21 °C and 23.8 weeks at 9 °C, 32.5 weeks at 4 °C for total anthocyanins) than in blackcurrant (t½ = 3.0 weeks at 21 °C, 11.5 at 9 °C and 20.3 weeks at 4 °C) and crowberry juice (t½ = 2.2 weeks at 21 °C, 7.3 at 9 °C and 12.3 weeks at 4 °C). It was also evident that the long shelf life often applied for the commercial juice drinks is detrimental to the anthocyanins. Only 11-15% of the original anthocyanin content was detected in two commercial juice drinks at their expiry date, after storage of 35-49 weeks at room temperature.