Bread enriched with resveratrol: Influence of the delivery vehicles on its bioactivity

Abstract

Trans-resveratrol (RSV) is recognised as a bioactive ingredient in the development of functional foods. Its stability, solubility, and bioavailability constraints can be overcome by delivery systems, not yet tested in foods. This study aims at evaluating the impact of two delivery systems on the stability, antioxidant activity, bioaccessibility and bioavailability of RSV integrated into a bread matrix: an inclusion complex of RSV and γ-cyclodextrin (γCD·RSV) and RSV loaded zein nanoparticles (nZ-RSV). Wheat bread was supplemented with 0.5% of pure RSV (RSV-bread) and equivalent amounts of γ-CD·RSV and nZ-RSV. The amount of RSV recovered from the hydroethanolic extracts of γ-CD·RSV- and nZ-RSV-bread was 70.3% and 62.8% of the initial amount, respectively, lower than RSV-bread extract, 89.0%, indicating lower degradability during bread preparation. Both vehicles helped to retain RSV antioxidant activity but did not increase RSV bioaccessibility (c.a. 40% for free RSV and γCD·RSV, and 29% for nZ-RSV). In vitro tests on intestinal cell monolayers showed that, after 4 h of contact, only 5.0% of the initially available amount of RSV was able to permeate the intestinal barrier in all samples. Thus, bread itself is a vehicle for RSV integration into our daily diet, without the need for an additional delivery system.