Effect of modified atmosphere on polyphenols during storage of pasteurised strawberry purées

The minimum loss of processed fruit nutritional quality must been guaranteed during storage and the atmosphere can be a limiting step. Strawberry purées flushed with gas mixtures: 10kPa O2+90kPa N2, 100kPa N2 and air (78kPa N2+21kPa O2+0.03kPa CO2) were stored for 90 days at 4 and 23°C and revealed no effect in total antioxidant activity and in total phenolic content. The compounds (+)-catechin, (-)-epicatechin and quercetin-3-rutinoside were not affected by the atmospheres for both temperatures and ellagic acid was the exception within strawberry phytochemicals, where its concentration was higher for samples stored in air. Total anthocyanin content was better preserved when strawberry purée was stored in 100kPa N2 at 4 and 23°C, at which temperatures their levels decreased 24 and 77%, respectively. At 4°C cyanidin-3-glucoside presented no significant differences between atmospheres. Pelargonidin-3-glucoside and pelargonidin-3-rutinoside decreased both 27% for 100kPa N2 and 45% for 10kPa O2 and air. All the individual anthocyanins were not affected by the atmospheres when stored at 23°C.