Pereira-Caro, G. (Gema)

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    Influence of heat treatment on antioxidant capacity and (poly)phenolic compounds of selected vegetables
    (Elsevier, 2016) Pereira-Caro, G. (Gema); Juaniz, I. (Isabel); Ludwig, I.A. (Iziar Amaia); Cid, C. (Concepción); Peña, M.P. (María Paz) de; Moreno-Rojas, J. M. (José Manuel); Huarte, E. (Estibaliz)
    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.
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    Digestibility of (Poly)phenols and Antioxidant Activity in Raw and Cooked Cactus Cladodes (Opuntia ficus-indica)
    (2018) Santiago, E. (Elsy) de; Pereira-Caro, G. (Gema); Cid, C. (Concepción); Peña, M.P. (María Paz) de; Moreno-Rojas, J. M. (José Manuel)
    This study aims to investigate whether heat treatment applied to cactus cladodes influences the bioaccessibility of their (poly)phenolic compounds after simulated gastric and intestinal digestion. A total of 45 (poly)phenols were identified and quantified in raw and cooked cactus cladodes by ultra high performance liquid chromatography photodiode array detector high resolution mass spectrometry. Both flavonoids (60-68% total), mainly isorhamnetin derivatives, and phenolic acids (32-40%) with eucomic acids as the predominant ones significantly ( p < 0.05) increased with microwaving and griddling processes. After in vitro gastrointestinal digestion, 55-64% of the total (poly)phenols of cooked cactus cladodes remained bioaccessible versus 44% in raw samples. Furthermore, digestive conditions and enzymes degraded or retained more flavonoids (37-63% bioaccessibility) than phenolic acids (56-87% bioaccessibility). Microwaved cactus cladodes contributed the highest amount of (poy)phenols (143.54 mg/g dm) after gastrointestinal process, followed by griddled samples (133.98 mg/g dm), showing the highest antioxidant capacity. Additionally, gastrointestinal digestion induced isomerizations among the three stereoisomeric forms of piscidic and eucomic acids.