Fresh fruit of three strawberry cultivars Fragaria ananassa × Duch. (cvs. ‘Clery’, ‘Honeoye’ and ‘NF 421’ (Asia)) were investigated and used to produce jams, which were analyzed before and after dark storage at 20 °C for six months. The aim of this investigation was to characterize all the samples in relation to the total phenolics, flavonoids, nonflavonoids, total anthocyanins and antioxidant activity. Among investigated strawberry fruit cv. Clery showed the highest amount of total phenolics, while regarding to total anthocyanins, cvs. ‘Honeoye’ and ‘NF 421’ showed higher amounts of total anthocyanins. The jam processing under applied conditions had appreciable effects on preserving stability of polyphenolics.
Our results showed that total phenolics were more stable during processing in comparison with total anthocyanins. Furthermore, in all investigated samples flavonoids were predominant. Relevant differences among cultivars were observed when total phenolics, total anthocyanins, flavonoid and nonflavonoid contents in jams were compared. After six months storage, in all investigated samples anthocyanins were at least stable, without marked influences of cultivar. Compared to the strawberry fruits, the jams also represented a significant source of antioxidant compounds, even considering the lower content of phenolic compounds. Six month storage had influence on further decrease of antioxidant activity. Among investigated samples, the highest correlation was found in the total anthocyanins contents and the DPPH. Hence, the obtained results showed that besides fresh strawberry fruit, the strawberry jams also possess noticeable content of important bioactive compounds with considerable antioxidant activity.

strawberry; jam; phenolics; antioxidant activity; storage

Published by University of Zagreb, Faculty of Agriculture, Zagreb, CROATIA
Sponsored by Ministry Science and Education of the Republic of Croatia