The Effect of Cultivar and Cultivation on Antioxidant Activity in Fresh and Processed Strawberries

The aim of this study was to investigate the stability of polyphenolics and to evaluate their antioxidant activity during processing and storage. Low sugar jams were prepared under vacuum from two strawberry cultivars Elasanta and Marmolada, grown in conventional and organic cultivation in Croatia. fresh fruit and prepared jams were analyzed before and after storage. Differences between strawberries from organic vs. conventional cultivatiuon were investigated and the influence of cultivar on phenolics and antioxidant activity was studied, too. Compared to conventional cultivation, organic cultivation had effect on slightly higher levels of total phenolics, flavonoids and nonflavonoids. In spite of this, conventional strawberries showed higher antioxidant activity. Among fresh samples it is observed that cv. Elsanta contains higher amounts of total phenolics and flavonoids while cv. Marmolada contains higher amounts of nonflavonoids. During processing into jams, greater stability of total phenolics can not be considerably associated to influence of cultivation or cultivar. Flavonoids showed slightly higher stability than nonflavonoids without greater imact of cultivar and cultivation. Conventional jams showed slightly higher stability of anthocyanins while cultivar effects were not noticed. After 6 months storage, total phenolics were more stable in conventional jams. Influence of cultivar was perceived in amounts of nonflavonoids and anthocyanins and influence of cultivation was noticed in amounts of flavonoids. Antioxidant activity did not change markedly during processing neither during storage, so antioxidant activity of fresh atrawberries is comparable to their jams and both are certainly recommended as rich source in natural antioxidants.