Microbial catabolism of coffee pulp (poly)phenols during in vitro colonic fermentation
Silvia Cañas, Nicole Tosi, Vanesa Núñez-Gómez, Daniele Del Rio, Pedro Mena, María Á. Martín-Cabrejas, Yolanda Aguilera
Abstract
Coffee pulp is a by-product characterized by its richness in phenolic compounds. This study examined the catabolism of (poly)phenols in digested coffee pulp flour (CPF) and extract (CPE) during in vitro colonic fermentation. After a simulated gastrointestinal digestion, samples were fermented using human microbiota and (poly)phenol transformations were analyzed by UHPLC-ESI-MS/MS. Digested CPF and CPE contained high amounts of phenolic acids, notably 3′,4′-dihydroxycinnamic (99.7–240.1 μmol 100 g −1 ) and 3,4-dihydroxybenzoic acid (174.1–491.4 μmol 100 g −1 ). During the in vitro fecal fermentation, phenylpropanoic acids (1.5- to 2.6-fold), phenyl-γ-valerolactones (1.3- to 23-fold), phenylvaleric acids (1.1- to 2-fold) and benzene derivatives (1.5-fold) increased; while benzoic and cinnamic acids, cinnamoylquinic derivatives, flavonols, benzaldehydes and diphenylpropan-2-ols decreased. The (poly)phenols in CPF were catabolized more slowly than in CPE, suggesting protection of the fibrous matrix against phenolic degradation. Coffee pulp may be a promising food ingredient rich in (poly)phenols contributing to the prevention of intestinal diseases. • High amounts of caffeic and protocatechuic acids were found after digestion. • The concentration of (poly)phenols decreased throughout fecal fermentation. • Benzoic and cinnamic acids decreased in concentration in both CPF and CPE. • Phenylpropanoic acids and phenyl-γ-valerolactones increased upon fermentation. • The coffee pulp matrix affected phenolic compounds release during fermentation.