Evaluation of Drying Temperature and Air Velocity Dependent Profile of Bioactive Compounds, and Antioxidant Capacity of Black Mulberry (Morus Nigra L.) Fruit: a Chemometric Approach

Abstract

The aim of this study was to determine the effect of drying temperature (50, 60, 70, and 80 °C) and air velocity (AV) (2 m/s and 3 m/s) on the phenolic compounds, antioxidant capacity, total phenolic and monomeric anthocyanin contents, and color parameters (L*, a*, b*, C*, h) of the black mulberry (Morus nigra L). The phenolic compounds and antioxidant capacity of the fruit decreased under all drying temperature and air velocity conditions; however, higher drying temperatures combined with higher air velocity resulted in comparatively better retention of total phenolics and antioxidant capacity than lower temperature and air velocity conditions. Anthocyanins and other phenolics detected in the fruit were protected better by drying at 60 °C drying temperature and 3 m/s air velocity. While the L* and b* values generally increased, the a* value decreased as a result of the drying process. In terms of the properties considered, the product obtained by drying at 50°C and 2 m/s air velocity was found to be of the lowest quality. Principal component analysis (PCA) and hierarchical classification analysis (HCA) showed that the samples dried at 70 and 80 °C at both air velocities and the sample dried at 60 °C at 3 m/s air velocity were grouped with the fresh sample in terms of phenolic components and antioxidant capacity. In conclusion, drying at 70 °C and 3 m/s air velocity for color, 80 °C and 3 m/s air velocity for antioxidant capacity, and 60 °C and 3 m/s air velocity for phenolic compounds can be recommended in dried mulberry production.