Abstract: In this work, the effects of spray drying process parameters such as vacuum dehydration ratio, inlet air temperature and feeding rate on the recovery and antioxidant properties of protein hydrolysate powder were explored by response surface methodology. Mathematical predictive models were established, respectively, describing hdyrolysate recovery and reducing power, hydroxyl free radical scavenging activity and Fe2+ chelating activity as a function of these three spray drying process parameters. The prepared powder had certain antioxidant activity, which was dependent on the spray drying process parameters. Process parameters optimization was performed using the SAS software, and the optimized parameters were experimentally validated. In general good results for the spray drying of sweet almond protein hydrolysate could be achieved with a vacuum dehydration ratio of 0.5－0.6, an inlet air temperature of approximately 200 ℃, and a feeding rate of f 270－320 mL/h.

Key words: sweet almond, protein hydrolysate, spray drying, antioxidant activity