Biosorption of phenolic compounds from Plinia cauliflora seeds in residual yeast: Kinetic, equilibrium, and bioaccessibility studies

Abstract

This study aimed to evaluate the biosorption mechanisms of bioactive compounds from jaboticaba (Plinia cauliflora) seeds adsorbed on residual Saccharomyces cerevisiae. The bioaccessibility of bioactive compounds before and after the biosorption process was tested using the simulated gastrointestinal digestion technique. The biosorption process was evaluated at different solution pH values (2, 4, 6, and 8). In the present study, the biosorption occurred more favorably in an acid solution medium, and the highest adsorption capacity was found at pH 2 (qe = 49 mg g−1). In alkaline conditions (pH > 7), the biosorption was disfavored. The biosorption kinetics of phenolic compounds from jaboticaba seed extract in yeasts showed a fast equilibrium time (45 min). In addition, 80% of biosorption occurred within the first 15 min. Regarding the isotherm studies, the increased adsorption capacity observed was directly proportional to the increase in the concentration of the initial solution, presenting an L-type curve characteristic of monolayer adsorption. The Sips and Jovanovic monolayer models suggest that the maximum adsorption capacity (q) was 75 mg g−1. According to the separation factor (RL) of the Langmuir model, the adsorption of the phenolic compounds extracted from the jaboticaba seeds occurred favorably (RL = 0.509). In addition, the concentration of total phenolic compounds after simulated gastrointestinal digestion was reduced in crude and biosorbed extracts, with bioaccessibility values of 5.37 and 2.64, respectively. However, the concentration of these total compounds increased after intestinal digestion of the biosorbed yeast. The biosorption equilibrium time was reached at 45 min, and the maximum adsorption capacity for the concentrations studied was 50 mg g−1 at pH 2. These results show that S. cerevisiae is a biosorbent capable of protecting and releasing compounds during gastrointestinal digestion and acts as a polyphenol delivery system. Novelty impact statement Yeasts biosorbed with bioactive compounds of plants can be used as a delivery system of secondary metabolites where the enriched biomass act in preserving the antioxidant and bioaccessibility of the molecules.