Bioaccessibility of (poly)phenolic compounds of raw and cooked cardoon (Cynara cardunculus L.) after simulated gastrointestinal digestion and fermentation by human colonic microbiota

A total of 17 (poly)phenolic compounds have been quantified in the free and bound fraction of raw, olive oil fried, sunflower oil fried and griddled cardoon (Cynara cardunculus L.). Caffeoylquinic acid derivatives (CQAs), particularly 5-CQA, were the major compounds. The bioaccessibility of (poly)phenols after gastrointestinal digestion and fecal fermentation (24 h) was studied. Heat treatment exerted a positive effect on the bioaccessibility of (poly)phenols. In raw cardoon, only 2% of the total amount of (poly)phenolic compounds was still bioaccessible after gastrointestinal digestion, while in cooked cardoon samples, between 60 and 67% of the total amount of (poly)phenolic compounds remained unmodified. An important microbial metabolic activity was observed during the fecal fermentation, which resulted in a complete degradation of CQAs after 5 h and in the formation of different catabolites. 3-(3′-hydroxyphenyl)propionic acid was by far the most abundant catabolite produced. Catabolic pathways for colonic microbial degradation of CQAs of cardoon have been proposed.