In vitro evaluation of the bioaccessibility of phenolic acids in different whole wheats as potential prebiotics

Abstract

Whole wheat has often been associated with health benefits conveyed by the phenolic acids made accessible in the colon which enable the modulation of the gut microbiota. In the present study, the bioaccessibility of nine individual phenolic acids present in different wheat varieties was evaluated by in vitro gastrointestinal digestion and colonic fermentation. Most of the individual phenolic acids in the complex wheat matrix had a higher bioaccessibility after the in vitro digestion step (average 57.7%–82.1%), than after in vitro colonic fermentation (21.9%–47.5%). However, the contents of cinnamic, caffeic, and protocatechuic acids in several wheat varieties were higher in the intestinal digesta than in the undigested samples, and the content of erucic acid was higher in fermented slurry than in the intestinal digesta. The bioaccessibility of certain phenolic compounds also varied significantly between different wheat varieties. Other compounds in wheat interfered with the release of phenolic acids during digestion and fermentation. The contents of phenolic acids remaining in the digesta were significantly correlated with the abundance of at least one bacterial genus during colonic fermentation. This suggests that both concentrations and food composition should be considered when selecting whole wheat with associated phenolic acids for use as potential prebiotics.