In vitro assessment of the effect of microencapsulation techniques on the stability, bioaccessibility and bioavailability of mulberry leaf bioactive compounds

Mulberry (Morus alba L.) leaf extract is well-known for its health-promoting features. However, food processing conditions affect its bioactive profile, which could be limited by encapsulation. Nevertheless, assessing the impact of encapsulating techniques on the digestibility of embedded biocompounds requires further knowledge. Hence, the aimed of this study was to assess the effects of carrier materials and drying techniques on (i) bioaccessibility and bioavailability indexes, (ii) stability of nutraceuticals, and (iii) changes in antioxidant activities of mulberry leaf extract powder by using an in vitro oral-gastrointestinal digestion. Digestion was performed out at 37 C in darkness by shaking encapsulated extract with human saliva during 2 min, followed by 2 h of incubation with a pepsin-HCl mixture, then mixed for 2 h with bile salts and pancreatin. After digestion the samples were acidified and HPLC assayed. A significant (p < 0.05) decrease in nutraceuticals content was noted during the intestinal phase with more reduction in gamma-aminobutyric acid (34.91-51.14%) compared to that of flavonols (16.58-28.90%), 1-deoxynojirimycin (17.56-20.42%) and phenolic acids (0.53-0.67%) in the gastric digesta. Although encapsulation was observed to enhance the bioaccessibility, negative effects were found in terms of the bioefficiency and bioavailability. Furthermore, encapsulation techniques mostly affected the ion reducing capacity than the radical scavenging capacity. The outcomes suggested that carriers had a major effect on the digestibility and antioxidative activity, whilst the drying techniques mostly affect the bioaccessibility and bioavailability of the flavonols.

Automated summary

This study assessed the effects of carrier materials and drying techniques on the digestibility and antioxidant activity of mulberry leaf extract. The results showed that encapsulation enhanced bioaccessibility but had negative effects on bioefficiency and bioavailability. Furthermore, carriers had a major impact on digestion and antioxidative activity, while drying techniques mostly affected the bioaccessibility and bioavailability of flavonols.