Effect of temperature and storage time on bioactivity and physicochemical stability of nanovesicles containing hydrolyzed bee pollen protein

In this study, the effect of temperature and storage time on biological activity and physicochemical stability of nanovesicles (liposomes and niosomes) containing bee pollen hydrolyzed protein obtained from alcalase and pepsin enzymatic hydrolysis was evaluated. 0.2% chitosan was used to coat nanoliposomes. DPPH radical scavenging power, ferric ion reducing power, ACE scavenging power, particle size, particle dispersion index, zeta potential, encapsulation efficiency and release rate of hydrolyzed proteins from nanovesicles during 28 days storage at refrigerator and ambient temperature were investigated. Results of DLS showed that the size of nanovesicles increased significantly by loading with hydrolyzed protein and coated with chitosan (P<0.05). Chitosan coated nanoliposomes had the highest amount of PDI. The zeta potential of nanovesicles reached the highest value by coating with chitosan. Chitosan coated nanoliposomes had the highest encapsulation efficiency. After 28 days, the size of coated and uncoated nanovesicles increased 2-26 times.The encapsulation efficiency of nanonisomes and uncoated nanoliposomes showed the lowest and highest decrease, respectively. The values of the measured factors during storage at the refrigerator were significantly lower than ambient temperature (P<0.05). The decline in the antioxidant activities of nanovesicles was significantly prevented by loading hydrolyzed proteins and coating the nanovesicles with chitosan. The ACE inhibition was lower in the nanoliposomes as compared with the nanoniosomes. After 28 days, the ACE inhibition activity of the loaded in nanoliposomes without coating chitosan decreased slightly. These findings are of great importance for designing and developing nutritious foods containing hydrolyzed protein.