Effect of drying kinetics on main bioactive compounds and antioxidant activity of acerola (Malpighia emarginata D.C.) residue

Abstract

This study investigates the drying kinetics of residue of acerola, in a fixed-bed dryer, analysing the effect of the process variables on the antioxidant properties of the residue. A complete factorial design 32 has been performed, where the independent variables studied were as follows: air velocity (0.5, 1.0 and 1.5ms-1) and air-drying temperature (40, 50 and 60°C). The bioactive compounds studied were L-ascorbic acid, total phenolic, total flavonoids and antioxidant activity (expressed as IC50) was determined using free radical DPPH•. Both independent variables studied have shown to be statistically significant. The content of ascorbic acid was the highest at 60°C and 1.0ms-1 (126.2±0.004mg100g-1) while for the fresh residue 16.12±0.003mg100g-1, whereas the total phenolic showed the highest content at 50°C and 1.5ms-1 (46.2±0.003mg gallic acid.100g-1) while for the fresh residue 12.59±0.001mg gallic acid.100g-1. The drying conditions play an important role in determining the final quality of the product mainly in terms of antioxidant activity. © 2013 The Authors. International Journal of Food Science and Technology © 2013 Institute of Food Science and Technology.