Potential bioaccessibility of phenolic acids in whole wheat products during in vitro gastrointestinal digestion and probiotic fermentation

•Potential bioaccessibility of whole wheat bread, cookie, and pasta was studied.•Phenolic acid concentrations changed mostly within the first hour of gastric and intestinal digestions.•Probiotic fermentation released additional phenolic acids from digestive residues.•Phenolic profiles are better estimated by digestion methods than chemical extractions. Health benefits of whole wheat products are partially attributed by their unique phenolic compounds. This study investigated effect of simulated gastrointestinal digestion and probiotic fermentation on releasing of phenolic acids from whole wheat foods (bread, cookie, and pasta). Kinetics results showed that more phenolic acids were released within the first hour of gastric and intestinal digestions compared to the prolonged digestion. Lactobacillus rhamnosus GG, a common probiotic strain, released additional phenolic acids from the digestive residues during fermentation. Simulated digestion released more soluble trans-ferulic acid than chemical extraction in breads (17.69 to 102.71 µg/g), cookie (15.81 to 54.43 µg/g), and pasta (4.88 to 28.39 µg/g). Phenolic acid composition of whole wheat products appeared to be better estimated by digestion methods than the chemical extraction method. The unique insoluble-bound nature and fermentability of wheat phenolic acids may lead to a mechanistic understanding of whole grain consumption for potential colorectal cancer prevention.