Soy protein-based delivery systems as carriers of trans-resveratrol: Bioaccessibility using different in vitro digestion models

Ingestion of trans-resveratrol promotes health benefits, but the low solubility and chemical stability of this compound may hamper its bioaccessibility. To overcome these drawbacks, O/W emulsions loaded with resveratrol (liquid or gelled) and stabilized by soy protein isolate (SPI) were used to protect and vehiculate the bioactive compound to the target absorption site. Two distinct strategies were used to allow protein denaturation: heating the A) aqueous phase of the emulsion before homogenization; or B) emulsion after homogenization. Delivery efficacy of resveratrol was evaluated by static or semi-static in vitro digestion assays. For the semi-static approach, a dynamic gastric model was developed that was able to simulate the intensity of contraction forces and the gradual decrease of pH in the gastric step in vivo. The structure of the liquid emulsions remained similar in the static and semi-static digestion approaches, showing little influence of peristalsis on droplet size. The gelled emulsions showed breakdown of the gel network in the presence of the mechanical forces of the semi-static tests, although its structure was not completely degraded at the end of the in vitro digestibility tests. Anyway, the results of bioaccessibility of the carriers were similar (around 70-75%) and high, being these emulsions effective carriers of resveratrol. However, the bioaccessible fraction of liquid emulsions was much higher after digestion under static conditions, showing the relevance of developing dynamic systems for a more realistic simulation of in vitro digestion processes.