Spray-drying of grape skin-whey protein concentrate mixture.

The aim of this work was to evaluate the effect of process conditions (inlet air temperature, paste flow rate, and whey protein concentration) on the physical and physicochemical characteristics of the powder obtained from spray dried grape skin-whey protein concentrate mixture. The experiments were performed according to the 23 factorial design, with repetition of the central point. The highest values of anthocyanin retention (> 92%) were obtained with the highest inlet air temperature (190 °C) and the highest whey protein concentration (15% (w/w)). The powder also showed solubility above 78.3%, and low values of moisture content, hygroscopicity and bulk density. Spray drying of grape residues, using whey protein as carrier agent, resulted in a powder with a high level of anthocyanin retention and of good quality, showing a potential application in food products. Therefore, the method indicates a possible alternative to change post-harvesting waste in a natural source of bioactive compounds.