Evaluation of the bioaccessibility of peanut skin polyphenols and their potential use for food enrichment

Abstract

Polyphenols obtained from agricultural and industrial residues are also considered as remarkable sources of natural antioxidants to replace synthetic ingredients. In this study, the contents of total polyphenols (TP) and total flavonoids (TF), antioxidant capacity (AC) and in-vitro bioaccessibility of polyphenols (as gastric and intestinal stages) of the extract from peanut skin using water were investigated. Additionally, the potential use of peanut skin extract in noodle production was researched in order to add functionality to noodle, which is a widely consumed product. The results showed that 71.67 mg gallic acid equivalent (GAE)/g dry matter (DM) of TP, 123.11 mg rutin equivalent (RE)/g DM of TF and 66267.46 mmol ascorbic acid equivalent (AAE)/100g DM of AC were found in peanut skin. After the gastric and intestinal stages, the TP content and AC of the skin extract were found to be lower than the initial (before digestion) value. It was determined that polyphenols were more stable in gastric conditions than in the small intestine. The addition of the skin extract (0.4%) to the noodle dough increased the TP and AC of the final product compared to the noodle without the skin extract (control). It was observed that the stability of the polyphenols from the noodle sample was higher in gastric stage than intestinal one. The addition of peanut skin extract to the noodle dough increased the bioaccessibility of the polyphenols. Therefore, this study showed that peanut skin, as an important source of polyphenols, may be useful for food enrichment.