Effects of drying and extraction methods on bioactive properties of plums

Abstract Plums are a popular fruit whose large quantities are subjected to processing, which contributes to changes in the physicochemical parameters, and the magnitude of these changes is determined by the technology applied. The study aimed to analyse the bioactive compound content and the antioxidant capacity of plums of the Bluefree, Stanley and Sweet Common Prune (Wegierka Zwykla) varieties, depending on the drying and extraction processes applied. Significant differences in the bioactive compound content and the antioxidant capacity were found between the varieties under study. The convection drying process resulted in the greatest significant decrease in both the anthocyanin pigment content (by an average of 82%) and the total polyphenol content (by an average of 41%). The average losses of phenolic acids reached 34%, and the greatest decrease was noted for chlorogenic acid (an average of 69%). As regards flavan-3-ols and flavonols, the drying processes caused their losses by an average of 56%. The vacuum drying and lyophilisation processes applied were softer for the tested bioactive compounds. Moreover, these processes reduced the ABTS and FRAP antioxidant capacity. The ultrasound- and microwave-assisted extraction increased the total anthocyanin content by an average of 29%. These methods yielded significantly greater amounts of all four determined anthocyanins in the tested fruit. The results show that the search for a safe, inexpensive raw material drying method is still a current research issue.