The effect of thermal processing and storage on the color stability of strawberry puree originating from different cultivars

Abstract

The effect of cultivar on color (CIELab values, anthocyanin content and % polymeric color), chemical composition (vitamin C, total phenolic content) and enzyme activities during thermal processing and subsequent storage (35 °C for 14 days) as well as their suitability for puree processing was evaluated for twelve strawberry cultivars. Degradation of anthocyanins, color (based on a* and C* values) and total phenols during thermal processing (95 °C, 1 min) was cultivar dependent whereas vitamin C decreased similarly in all cultivars. Despite different levels of POD and PPO activity observed in fresh purees of the different cultivars, these enzymes were completely inactivated in all cultivars after pasteurization. Anthocyanin degradation, which was accompanied by a fade in red color, and loss of vitamin C were remarkable during a 14-day storage period, but the rate differed among the cultivars. In contrast, polymeric color formation was unaffected by the cultivar. Despite the differences in initial chemical composition, Rendezvous, Senga Sengana and 6082 were the cultivars exhibiting the highest anthocyanin stabilities and lowest % polymeric color values after storage, being good candidates for processing, and suggesting that some intrinsic factors (e.g. copigments) in these cultivars could affect anthocyanin stability.