The use of extracts from peanut, chestnut and hazelnut shells for enhancement of phenolic substances of noodles

In this study, peanut, chestnut and hazelnut shell extracts were investigated in terms of total polyphenol (TP) and total flavonoid (TF) content, antioxidant capacity (AK), individual phenolic compounds and in vitro bioaccessibility of their polyphenols (as stomach and intestinal stage). In this study, the potential use of suitable shell in noodle production was investigated in order to add functionality to noodle, which is one of the commonly consumed products. The results showed that the highest amount of TP (172,67mg gallic acid equivalent (GAE)/g dry matter (DM)) and AK (174319,64 mmol ascorbic acid equivalent (AAE)/100g DM) were found in chestnut bark. Chestnut and peanut shells contained more TF (124,63 and 123,11 mg routine equivalents (RE)/g KM, respectively) than hazelnut shells, with no significant difference between results (p> 0,05). Among the phenolic compounds, gallic acid and ellagic acid were detected only in chestnut and hazelnut shells. After in-vitro digestion for all three shells, TP bioaccessibility decreased, with the greatest bioaccessibility observed at the end of the gastric stage. The bark extracts showed a decrease in AK, mostly in the intestinal phase. The addition of chestnut shell extract with the highest phenolic compounds and AK (1%) to the noodle dough increased the TP, TF and AK of the final product compared to the noodles without shell extract (control). As with the shell extract, it was observed that the stability of polyphenols obtained from the noodle sample was higher in the stomach stage than in the intestine. In addition, the use of shell extract in noodle formulation in creased the bioaccessibility of noodle polyphenols. The addition of shell extract decreased the uncooked noodle's lightness (L) while increasing its redness (a) but did not affected its yellowness (b). Unlike uncooked noodle, (b) value of noodle cooked decresed. As a result of the cooking process, weight gains for control and enriched noodles were determined as 166,34% and 332,34%, respectively. As a result, it has been seen that peanut, hazelnut and especially chestnut shell can be used as a good source of polyphenols for food enrichment.