The objective of this study was to determine changes in some selected bio-active components of strawberry juices and half-concentrates stored at a temperature of 4ºC. The contents of anthocyanins and polyphenols were measured in two products investigated. Additionally, the antioxidant activity of DPPH• was determined in juices, and the content of ascorbic acid in semi concentrates. The investigation included products from two strawberry cultivars: Honeoye, which is a very popular fresh fruit, and Senga Sengana – an industrial cultivar. Immediately upon the production, juices produced from the Honeoye cultivar contained, averagely, 22,9 mg/100 ml of anthocyanins, and from the Senga Sengana cultivar: 22,3 mg/100 ml; the content of total polyphenols was 123,2 and 105, 8 mg/100 ml, respectively. It was stated that the stability of anthocyanins was better in juices produced from the industrial cultivar, after they have been stored for 3 months. The antioxidant activity of juices produced from the Honeoye strawberries was 14,8 μmol of Trolox/1ml of juice, and it was 7,6 μmol of Trolox/1ml of juice in the juices from the Senga Sengana cultivar. Diverse changes in the content of bioactive components, active while storing juices, were found both in juices and in semi-concentrates under investigation. The chromatography analyses of the anthocyanins contents in semi-concentrates showed a time-dependent differentiation of the stability of individual monomers, and this differentiation impacted the rate of changes occurring.
strawberries, juices, semi-concentrates, polyphenols, anthocyanins, antioxidant activity