Bioaccessibility of (poly)phenolic compounds of raw and cooked cardoon (Cynara cardunculus L.) after simulated gastrointestinal digestion and fermentation by human colonic microbiota Isabel Juániz a,b , Iziar A. Ludwig c,1 , Letizia Bresciani c , Margherita Dall’Asta c , Pedro Mena c , Daniele Del Rio c , Concepcion Cid a,b , María-Paz de Peña a,b,⇑ a Universidad de Navarra, Facultad de Farmacia y Nutrición, Departamento de Ciencias de la Alimentación y Fisiología, C/ Irunlarrea 1, E-31008 Pamplona, Spain b IdiSNA, Navarra Institute for Health Research, Spain c The Laboratory of Phytochemicals in Physiology, LS9 InterLab Group, Department of Food & Drug, University of Parma, Parma, Italy article info Article history: Received 20 December 2016 Received in revised form 17 February 2017 Accepted 22 February 2017 Keywords: Cynara Polyphenols In vitro bioaccessibility In vitro gastrointestinal digestion Colonic catabolism Heat treatment abstract 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 gas- trointestinal 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 impor- tant microbial metabolic activity was observed during the fecal fermentation, which resulted in a com- plete degradation of CQAs after 5 h and in the formation of different catabolites. 3-(3 0 -hydroxyphenyl) propionic acid was by far the most abundant catabolite produced. Catabolic pathways for colonic micro- bial degradation of CQAs of cardoon have been proposed. Ó 2017 Elsevier Ltd. All rights reserved. 1. Introduction Cynara cardunculus L. belongs to the family of Asteraceae. In Spain, globe artichoke is the most commonly consumed part of Cynara cardunculus L. (2.6 g/capita/day). However, other parts of this vegetable, such as stalks (popularly named cardoon), are also consumed fresh in salads (when they are soft) and fried or griddled in typical meals (0.16 g/capita/day) (AECOSAN, 2011). Several studies report the (poly)phenolic composition of leaves and heads of globe artichoke. Its major (poly)phenols are caffeic acid derivatives, which mainly occur as esters with quinic acid (Hausler, Ganzera, Abel, Popp, & Stuppner, 2002; Mulinacci et al., 2004; Schutz, Kammerer, Carle, & Schieber, 2004; Wang et al., 2003). However, only a few studies about stalks (cardoon) compo- sition have been reported (Juániz, Ludwig, Huarte, et al., 2016; Ramos et al., 2014; Velez et al., 2012) and only two of them pro- vided information on (poly)phenolic profile by high-performance liquid chromatographic (HPLC) (Juániz, Ludwig, Huarte, et al., 2016; Ramos et al., 2014). Even the presence of bound phenolic compounds has been reported from the 1980s (Krygier, Sosulski, & Hogge, 1982a; Krygier, Sosulski, & Hogge, 1982b; Naczk & Shahidi, 1989; Sosulski, Krygier, & Hogge, 1982), none studies about free and bound phenolic compounds in cardoon have been found. The most abundant (poly)phenols of cardoon are chloro- genic acids (CGAs) (caffeoylquinic acids (CQA), diccaffeoylquinic acids (diCQA) and succinyldicaffeoylquinic acids (succinyldiCQA)). Traces of some flavonoids were also reported (Juániz, Ludwig, Huarte, et al., 2016). Vegetables are usually eaten cooked, and the softening effect of the cooking process due to heat-induced wall and cell ruptures can affect (poly)phenolic extractability (Palermo, Pellegrini, & Fogliano, 2014), possibly favoring the release of these compounds from the food matrix. Then, the action of digestive enzymes after consump- tion may further modulate and affect (poly)phenols bioaccessibil- ity. It is known that, in particular chlorogenic acids are characterised by a low absorption at small intestinal level (Erk et al., 2014), with a large amount reaching the colon to be then metabolized by the local microbiota to smaller and more absorb- able compounds (Ludwig, de Peña, Cid, & Crozier, 2013). http://dx.doi.org/10.1016/j.jff.2017.02.033 1756-4646/Ó 2017 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. E-mail address: mpdepena@unav.es (M.-P. de Peña). 1 Current address: Food Technology Department, Universitat de Lleida-Agrotecnio Center, Lleida, Spain. Journal of Functional Foods 32 (2017) 195–207 Contents lists available at ScienceDirect Journal of Functional Foods journal homepage: www.elsevier.com/locate/jff