Effect of temperature and shear stress on properties of nanovesicles carrying hydrolyzed pollen protein

Abstract

In this study, the effect of storage (65 °C, 24 h) and shear rates (2-100 s−1, 10 min) on the particle size, poly-dispersity index (PDI), encapsulation efficiency (EE), Angiotensin-converting enzyme (ACE) and DPPH radical inhibition, iron ion reduction ability and flow behavior of nanovesicles containing hydrolyzed bee pollen (produced by alcalase and pepsin) were evaluated. Nanoliposomes were coated by chitosan (0.2 % w/w). After storage at 65 °C, the size of the nanovesicles raised 2–2.5 folds while EE showed 5–8 % decline. ACE and DPPH radical inhibition activity were also decreased. After applying the shear stress, PDI was increased significantly (P<0.05), while EE of the nanoniosomes showed a drastic decline (P<0.05). Nanoliposomes and nanoniosomes exhibited decline in the ACE inhibitory and antioxidant activity. At low shear rates Newtonian-like and weak pseudo-plastic behavior of the chitosan-coated nanoliposomes were observed. The flow index (n), (k) and (R2) indicated the suitability of power law model for describing the flow characteristics.