Comparisons on the Functional Properties and Antioxidant Activity of Spray-Dried and Freeze-Dried Egg White Protein Hydrolysate

Freeze-dried and spray-dried egg white protein hydrolysates (FD-EWPH, SD-EWPH) prepared by papain were evaluated for their proximate composition, color, molecular weight distribution, physical structures, functional properties, and antioxidant activity. FD-EWPH and SD-EWPH had similar proximate composition and molecular weight distribution, but they had different color and physical structures. There was no significant difference (P>0.05) in solubility among egg white protein hydrolysate (EWPH) before drying (UD-EWPH), FD-EWPH, and SD-EWPH. The foaming properties of EWPH were improved by freeze-drying but reduced by spray-drying (P<0.05). Freeze-drying did not influence the emulsifying properties of EWPH while spray-drying had harmful effects on it. In the antioxidant test, no significant differences (P>0.05) in 1,1-diphenyl-2-picryl-hydrazyl radical-scavenging activity, reducing power, and lipid peroxidation inhibition was found among UD-EWPH, FD-EWPH, and SD-EWPH. The results indicated that spray-drying might be suitable to dry antioxidant hydrolysates for its simple, cost-effective, and time-saving process. Moreover, further modeling study of optimized spray-drying processing parameters is needed in order to minimize the emulsifying and foaming property damage.