Evaluation of the behaviour of bio-based nanostructures in food systems

Abstract

The growing consumers’ interest in healthier foods has led the food industry to develop functional foods specifically designed to improve human health, well-being, and performance. Curcumin is a natural polyphenol that presents numerous biological activities. However, curcumin has low water solubility, poor chemical stability, and low bioavailability. Lipid-based nanostructured delivery systems can be used to encapsulate curcumin. In this study, solid lipid nanoparticles (SLNs) encapsulating curcumin were developed and incorporated into a gelatine food matrix. SLNs (before and after incorporation in the gelatine) were characterized through mean diameter (Z-average diameter), polydispersity index (PDI) and zeta potential (ζ-potential) by Dynamic light scattering (DLS). Gelatine and gelatine-SLNs were evaluated through colour, texture, and rheology during 21 days of storage. In vitro digestion of the SLNs and gelatine-SLNs was performed and curcumin bioaccessibility, stability, and bioavailability were measured. The degree of hydrolysis (DH) of proteins and the production of free fatty acids (FFA) of gelatine and gelatine-SLNs were evaluated at gastric and intestinal phases, respectively. During 21 days, the Z-average diameter of the SLNs was maintained and the ζ-potential slightly decreased. The incorporation of the SLNs into gelatine did not significantly change neither the initial particle size nor PDI. ζ-potential of SLNs and gelatine-SLNs is different and this is due to the fact that gelatine has a slightly positive surface charge. The total colour difference (TCD) of the gelatine and gelatine-SLNs remained constant during 21 and 14 days of storage, respectively. The addition of SLNs did not lead to changes in the textural parameters of the gelatine, however, they promoted more solid behaviour to this food matrix. The value of DH of proteins in the gelatine and gelatine-SLNs were 47.8 % and 52.2 %, respectively. The total production of FFA of gelatine-SLNs was almost double of that of SLNs. Curcumin bioaccessibility and bioavailability were not statistically different between SLNs and gelatine-SLNs. However, the stability was higher in the gelatine-SLNs sample, suggesting that this food matrix provides a protective effect to curcumin. Finally, these results suggest that SLNs encapsulating curcumin and their incorporation in the gelatine food matrix is a promising application for the food industry.