Chemical changes caused by air drying of fresh plum fruits

Abstract

Drying of fresh plums may provide an excellent delicacy, but such technological process is inevitably followed by certain chemical changes. Three plum cultivars were dried at two different temperatures (70°C and 90°C), and the effect of drying procedure on total anthocyanins, flavonoids, phenolics, selected bioactive compounds and antioxidant capacity were monitored. Polyphenolic compounds suffered strong changes, depending on the applied drying temperature. Drying procedure at both 70°C and 90°C influenced to a great extent for total polyphenolic content in the fresh plums of ‘Čačanska Rodna’ (1.8 and 2.1-fold increase, respectively). The identical drying conditions showed almost no influence on plums of ‘Stanley’, while drying ‘Mildora’ at 70°C resulted in significant decrease, but higher temperature caused the opposite effect. Statistical analysis showed high correlation between polyphenolic content and antioxidant activity, in all tested cultivars and for both fresh plums and prunes. Caffeoylquinic acids and caffeic acids suffered certain changes depending on the cultivar and temperature applied. Anthocyanins completely disappeared after drying. Although drying of fresh plums prompted severe chemical changes, prunes might be considered as functional food due to the high level of antioxidant.