Bioaccessibility of polyphenolic compounds of six quinoa seeds during in vitro gastrointestinal digestion

The aim of this work was to evaluate the effect of simulated in vitro gastrointestinal digestion (GID) on (i) phenol and flavonoid recovery and bioaccessibility indexes, (ii) the antioxidant activity and (iii) the polyphenolic profile of six quinoa seeds. The recovery indexes obtained after the oral, gastric and intestinal digested fractions of quinoa seeds showed increasing concentrations of both total phenolic and flavonoid content. After GID, the average bioaccessibility percentage of samples was 73.29 and 12.64 for phenols and flavonoids, respectively. The LC-MS results obtained showed that the concentration of the polyphenolic compounds analyzed decreased after GID, although DPPH, TEAC-ABTS, FRAP and FIC assays pointed to a large increase in antioxidant activity. Of the investigated samples, red and black quinoa seeds showed the highest antioxidant activity, although they also seemed to be the most affected by GID. Further studies should be undertaken to understand the bioaccessibility of bioactive compounds in quinoa seeds and the factors that interfere with the same.