Valorization of Sweet Cherries (Prunus avium) Using Different Drying Methods for Obtaining a Healthy Dried Product

Large amounts of sweet cherries (Prunus avium) are annually discarded in Chile because they do not meet exportation standards, and these cherries are sold as fresh fruit in local markets at a low price. To increase the valorization of this important fruit and avoid environmental problems, different drying methods to process this fruit are proposed in this work. Five techniques were used: freeze-drying (FD); convective drying (CD); vacuum drying; infrared radiation (IRD); and solar drying. Fresh and dried samples were evaluated in terms of proximate composition, color, total phenolic content (TPC), total flavonoid content (TFC), total anthocyanin content (TAC), phenolic profiles, and antioxidant potential. Results showed that different drying methods have their respective advantages. For instance, FD samples showed the lowest total color change and highest TAC, as well as provided an increase of the chlorogenic acid (28.63 mg/100 g dry matter [d.m.]) with respect to the fresh material. CD significantly increased TPC (714 mg gallic acid equivalents/100 g d.m.) and TFC (589 mg quercetin equivalents/100 g d.m.), thereby demonstrating the highest free radicals (2,2-diphenyl-1-picryl-hydrazyl). Interestingly, IRD samples exhibited the highest antioxidant activity by oxygen radical absorbance capacity assay. Hence, considering the economic benefits of the process and the overall product quality, CD would be an effective drying method to use in sweet cherries with potential to replace FD.