THE EFFECT OF AIR-DRYING, FREEZE-DRYING AND STORAGE ON THE QUALITY AND ANTIOXIDANT ACTIVITY OF SOME SELECTED BERRIES

The aim of this study was to analyze the effects of air-drying and freeze-drying and subsequent storage of dried products on the content of polyphenols, anthocyanins and the antioxidant properties of selected berry fruits. The material was raspberry (Rubus ideaus L.), strawberry (Fragaria ananassa Duch) and bilberry (Vaccinum myrtillus). Despite exposure to atmospheric oxygen, the stored freeze-dried fruit retained the properties of the raw material better than the air-dried product. In the case of the latter, there were considerable differences in the retention of total polyphenolic and anthocyanin content as well as antioxidant properties in the three fruit species examined. In particular, bilberry maintained a high polyphenol and anthocyanin content and high antioxidant potential despite the greatest losses of these compounds.