Influence of drying processes on anthocyanin profiles, total phenolic compounds and antioxidant activities of blueberry (Vaccinium corymbosum)

Abstract

This work studies blueberry convective drying-process at 30, 40 and 50 °C, with the aim to obtain juices with the highest concentration of phenolics compounds and antioxidant activity. To predict changes in moisture content versus drying time, the results were adjusted to 5 mathematical models to evaluate the best fit, which is the one with the highest value of the coefficient of determination (R2) and lowest values the reduced chi square (χ2) and the root mean square error (RMSE). The Page model was the best model for the drying processes at 30 and 50 °C, while at 40 °C, the best model was the Approximation of diffusion model. The values of effective moisture diffusivity ranged between 2.58 × 10−11 and 4.58 × 10−11 m2/s, and the activation energy was 23.13 kJ/mol. The increase in temperature increased the absorbances at 420, 520 and 620 nm of the juice, the total phenolic contents (TPC) values and the anthocyanin concentration. The antioxidant activity, evaluated by the DPPH and ABTS methods, increased with the drying temperature. The best TPC values, antioxidant activity, anthocyanins concentration and color parameters were obtained from blueberries dried at 50 °C, being the most effective process in removing water.