Enzyme-assisted aqueous extraction processing(EAEP) is an environmentally friendly technology that simultaneously extracts both oil and protein.It has shown to be commercial feasibility for high oil recovery(97%) and favorable protein functionality properties.The present study used soy skim,the liquid co-products obtained using EAEP to produce a polypeptiderich spray-dried powder.The effects of inlet drying air temperature(140 ℃,160 ℃,180 ℃and 200 ℃),feed flow rate(3,6,9,and 12 m L/min),and solids concentration(25%,30%,35%,and40%) on the properties of the polypeptide-rich powders were investigated.Water activity(aw),color characteristics,bulk density,Carl Index(CI),Water Solubility Index(WSI),micro-morphology,peptide distribution,and antioxidant capacity were significantly affected by different spray-drying parameters.The results of antioxidant capacity test showed that the spray drying conditions significantly affected the antioxidant capacity of the polypeptide-rich powders.The polypeptide molecular weight size and distribution,the composition of the peptide chain,and the crosslinking with other substances could all affect its antioxidant capacity.Overall,good quality polypeptide-rich powders in terms of physicochemical characteristics,micro-morphology,and functional properties can be produced by spray-drying at an inlet temperature of 160 ℃,a feed flow rate of 6 m L/min,and solids concentration of 35%.
