(Poly)phenol characterisation in white and red cardoon stalks: could the sous-vide technique improve their bioaccessibility?

This study aims to evaluate whether sous-vide cooking better preserves the (poly)phenol content and profile of red and white cardoon stalks versus traditional boiling, both before and after simulated oral-gastro-intestinal digestion. Thirty one (poly)phenols were quantified in red and white cardoon by HPLC-MS/MS, phenolic acids being >95%, and 5-caffeoylquinic and 1,5-dicaffeoylquinic acids the major ones. Although both varieties showed a similar profile, raw red cardoon had 1.7-fold higher (poly)phenol content than raw white cardoon. Culinary treatments decreased (poly)phenol content, but sous-vide cooked cardoon had a greater content than the boiled one, suggesting a protective effect. After gastrointestinal digestion, (poly)phenol bioaccessibility of boiled and sous-vide cooked cardoon (52.6-90.5%) was higher than that of raw samples (0.2-0.7%), although sous-vide system no longer played a protective effect compared to boiling. In summary, red cardoon was a richer source of bioaccessible (poly)phenols than white cardoon, even sous-vide cooked or boiled.

Raw and Sous-Vide-Cooked Red Cardoon Stalks (Cynara cardunculus L. var. altilis DC): (Poly)phenol Bioaccessibility, Anti-inflammatory Activity in the Gastrointestinal Tract, and Prebiotic Activity.

The in vitro anti-inflammatory and prebiotic activity and the content and profile of bioaccessible (poly)phenols and catabolites of raw and sous-vide-cooked red cardoon (Cynara cardunculus L. var. altilis DC) were investigated during gastrointestinal (GI) digestion. Raw cardoon after in vitro GI digestion had 0.7% bioaccessible (poly)phenols, which protected against lipopolysaccharide-induced inflammation by counteracting IL-8, IL-6, TNF-α, and IL-10 secretions in differentiated Caco-2 cells. Contrarily, GI-digested sous vide cardoon showed higher (poly)phenol bioaccessibility (59.8%) and exerted proinflammatory effects in Caco-2 cells. (Poly)phenols were highly metabolized during the first 8 h of in vitro fermentation, and nine catabolites were produced during 48 h of fermentation. Colonic-fermented raw and sous-vide-cooked cardoon did not show anti-inflammatory activity in HT-29 cells but presented potential prebiotic activity, comparable to the commercial prebiotic FOS, by stimulating health-promoting bacteria such as Bifidobacterium spp. and Lactobacillus/Enterococcus spp. and by increasing the production of total SCFAs, especially acetate.

DNA damage and DNA protection from digested raw and griddled green pepper (poly)phenols in human colorectal adenocarcinoma cells (HT-29).

PURPOSE: To determine whether (poly)phenols from gastrointestinal-digested green pepper possess genoprotective properties in human colon cells and whether the application of a culinary treatment (griddling) on the vegetable influences the potential genoprotective activity. METHODS: (Poly)phenols of raw and griddled green pepper (Capsicum annuum L.) submitted to in vitro-simulated gastrointestinal digestion were characterized by LC-MS/MS. Cytotoxicity (MTT, trypan blue and cell proliferation assays), DNA damage and DNA protection (standard alkaline and formamidopyrimidine DNA glycosylase (Fpg)-modified comet assay) of different concentrations of (poly)phenolic extracts were assessed in colon HT-29 cells. RESULTS: A total of 32 (poly)phenolic compounds were identified and quantified in digested raw and griddled green pepper. Twenty of them were flavonoids and 12 were phenolic acids. Griddled pepper doubled the (poly)phenol concentration compared to raw; luteolin 7-O-(2-apiosyl)-glucoside and quercitrin constituted the major (poly)phenols in both extracts. Raw and griddled pepper (poly)phenolic extracts impaired cell proliferation and induced low levels of Fpg-sensitive sites, in a dose-dependent manner, even at a non-cytotoxic concentration. None of the concentrations tested induced DNA strand breaks or alkaline labile sites. Nor did they show significant genoprotection against the DNA damage induced by H2O2 or KBrO3. CONCLUSIONS: Green pepper (poly)phenols did not show genoprotection against oxidatively generated damage in HT-29 cells at simulated physiological concentrations, regardless of the application, or not, of a culinary treatment (griddling). Furthermore, high concentrations of (poly)phenolic extracts induced a slight pro-oxidant effect, even at a non-cytotoxic concentration.

Influence of heat treatment on antioxidant capacity and (poly)phenolic compounds of selected vegetables.

The impact of cooking heat treatments (frying in olive oil, frying in sunflower oil and griddled) on the antioxidant capacity and (poly)phenolic compounds of onion, green pepper and cardoon, was evaluated. The main compounds were quercetin and isorhamnetin derivates in onion, quercetin and luteolin derivates in green pepper samples, and chlorogenic acids in cardoon. All heat treatments tended to increase the concentration of phenolic compounds in vegetables suggesting a thermal destruction of cell walls and sub cellular compartments during the cooking process that favor the release of these compounds. This increase, specially that observed for chlorogenic acids, was significantly correlated with an increase in the antioxidant capacity measured by DPPH (r=0.70). Griddled vegetables, because of the higher temperature applied during treatment in comparison with frying processes, showed the highest amounts of phenolic compounds with increments of 57.35%, 25.55% and 203.06% compared to raw onion, pepper and cardoon, respectively.