Gelatin-based nanocomposite films activated by double emulsion loaded with “Pitanga” leaf extract: Bioaccessibility and cytotoxicity of emulsions and films after in vitro digestion

Abstract

The main aim of this study was to carry out an in vitro digestion of gelatin-based films and nanocomposite films activated with Pitanga (Eugenia uniflora L.) leaf extract (PLE) encapsulated in a W/O/W double emulsion. Also, the effects of encapsulation and addition of crystalline nanocellulose on PLE bioaccessibility, and on Caco-2 cells viability, after in vitro digestion, were evaluated. The free PLE, W/O (SE) emulsions and W/O/W (DE) emulsions were also submitted to in vitro digestion. The encapsulation of PLE within DE considerably increased the stability and bioaccessibility of PLE after in vitro digestion, which was also higher compared to SE. The PLE encapsulation within DE was positive compared to encapsulation only in SE, as DE also showed higher digestibility and lower cytotoxicity than SE. The active films and nanocomposite films showed lower PLE bioaccessibility when compared to SE and DE, but they were not cytotoxic to Caco-2 at all PLE concentrations studied. The PLE stability and bioaccessibility were higher using N-DE (nanocomposite film activated with DE). The effect of previously encapsulating PLE in DE, and the addition of crystalline nanocellulose in the film matrix, contributed to the protection of PLE's biological activity. Gelatin-based films and active nanocomposite films may have additional properties and applications in the food industry, as they have been shown to be active after in vitro digestion. Furthermore, DE was an effective encapsulation system for aqueous active compounds and can be potentially applied to several other areas of the food industry.