Efectos de la digestión gastrointestinal in vitro en la bioaccesibilidad de compuestos fenólicos y actividad antioxidante de dos matrices alimentarias de origen vegetal

Abstract

Polyphenols are secondary metabolites with bioactive properties, including antioxidant activity. Their availability after gastrointestinal digestion is crucial for their functionality, as only released phenols can be potentially utilized. This study aimed to evaluate the effects of in vitro gastrointestinal digestion on the bioaccessibility of phenolic compounds and antioxidant activity in two plant-based food matrices: grape pomace powder (POU) and amaranth flour (HA). The total polyphenol content (TPC) varied significantly (p<0.05) throughout the process, progressively increasing (oral < gastric < intestinal) in both samples. In the intestinal phase of POU, recovery was 2.5 times higher than previously reported for white grape pomace, whereas in HA, a possible overestimation of TPC was identified, as values in this phase were 3.2 times higher than those obtained in the control. Regarding bioaccessibility, POU exhibited a recovery comparable to that of fresh blueberries (15%), whereas in HA, it increased significantly (>300%), possibly due to the interaction of other components with the Folin-Ciocalteu reagent. Antioxidant activity (AA) showed a strong correlation with TPC in POU, in contrast to HA, where the relationship was negative, suggesting the involvement of other compounds in AA. These findings highlight the importance of considering the bioaccessibility of polyphenols from different plant matrices to understand their potential health impact and application in functional foods.