Physicochemical stability and in vitro bioaccessibility of β-carotene nanoemulsions stabilized with whey protein-dextran conjugates

In this study, β-carotene (BC)-loaded nanoemulsions encapsulated with native whey protein isolate (WPI) and WPI-dextran (DT, 5 kDa, 20 kDa, and 70 kDa) conjugates were prepared and the effects of glycosylation with various molecular weight DTs on the physicochemical property, lipolysis, and BC bioaccessibility were evaluated. Mean particle diameter of BC-loaded nanoemulsions stabilized with WPI-DT (5 kDa, 20 kDa, and 70 kDa) conjugates (156.8, 156.0, and 155.6 nm) were significantly lower than that stabilized with native WPI (165.6 nm). The pH stability of BC-loaded nanoemulsions, especially when the pH was close to the isoelectric point of 5.0 was remarkedly improved after glycosylation regardless of the molecular weight of DTs. No appreciably creaming or flocculation was observed for all nanoemulsions after 30 days of storage at 25 and 50 °C. BC retention was the highest at both temperatures when stabilized with WPI-DT (5 kDa) conjugates due to the relatively higher DPPH scavenging ability. When glycosylated 70 kDa DT, the encapsulated nanoemulsions had remarkable inhibition on the extent of lipolysis and release of BC. A positively linear correlation between lipolysis and BC bioaccessibility was found. The information obtained in this study will facilitate the uses and applications of nutraceuticals-loaded nanoemulsion delivery system.