The aim of this study was to assess the content of total polyphenols and anthocyanins together with antioxidant activity in strawberry juices. Also the addition of pectin was done in order to check its influence on radical scavenging activity during storage in 4°C. The amount of anthocyanins right after production reached 14.5 mg/100 ml and 12.1 mg/100 ml in control and pectin enriched samples respectively. The major anthocyanin monomer was pelargonidin-3-glucoside (89% of all anthocyanins). After three months of storage samples without pectin lost 57% of anthocyanins, whereas those with addition of pectin only 34%. During storage the decrease of total polyphenols was also found and as a result the antioxidant activity was smaller. The amount of total polyphenols that were lost reached 17% and 9% in control and pectin samples respectively. The measurement of antioxidant capacity using EPR method proved, that pectin prevents the loss of polyphenols, thus keeping radical scavenging activity of strawberry juices at high level. The activity in samples with pectin was only 7% lower, while in control samples it dropped down 28%.
strawberries, juices, anthocyanins, antioxidant activity, EPR, free radicals