Effect of the condition of spray-drying on the properties of the polypeptide-rich powders from enzyme-assisted aqueous extraction processing

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 polypeptide-rich spray-dried powder. The effects of inlet drying air temperature (140 °C, 160 °C, 180 °C and 200 °C), feed flow rate (3, 6, 9, and 12 mL/min), and solids concentration (25%, 30%, 35%, and 40%) 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 cross-linking 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 °C, a feed flow rate of 6 mL/min, and solids concentration of 35%.