Hot-air drying and degradation kinetics of bioactive compounds of gilaburu (Viburnum opulus L.) fruit

Abstract

The purpose of this study is to determine whether drying is a suitable preservation method for gilaburu fruit and to determine the changes in the bioactive components of gilaburu fruit (Viburnum opulus L.) at the end of the drying process. In this study, gilaburu fruits were dried in cabinet dryer at different temperatures (50,60 and 70?C). The analyses of trans-resveratrol, water-soluble vitamins, organic acids and phenolic compounds were made by using the HPLC method while total phenolic contents and antioxidant activity were spectrophotometric. As a result of drying of gilaburu fruit at 50, 60 and 70?C, the highest component loss was observed at 70?C. A loss of 73.64% and 84.08%, respectively, was detected in the total phenolic substance and antioxidant capacity content of gilaburu fruit after drying at 70?C. While the trans-resveratrol content was 1.26?0.05 (g/100 g dry weight (DW)) in fresh fruit, it reduced to 0.31?0.03, 0.30?0.01 and 0.21?0.01 after drying at 50, 60 and 70?C, respectively. In terms of vitamins, the highest loss was seen in niacin. The contents of ascorbic acid, pyridoxine, niacin and thiamine contents of fresh gilaburu fruit decreased from 0.78, 3.14, 0.12 and 0.30 g/100 g to 0.24, 0.75, 0 and 0.14 g/100 g, respectively, after drying at 70?C. In addition, drying kinetics of water-soluble vitamins, total phenolic contents, antioxidant activity and trans-resveratrol were modeled. The Page model best described the drying behavior of fruits at 70?C, and the Parabolic model at both 50?C and 60?. Thermal degradation of water-soluble vitamins, total phenolic contents, antioxidant activity and trans-resveratrol were fitted the first-order kinetic model.