Digestibility of (Poly)phenols and Antioxidant Activity in Raw and Cooked Cactus Cladodes (<i>Opuntia ficus-indica</i>)

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 (<i>p</i> < 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