İncedayı B. , Türkmen Erol N.

7th International Agriculture Congress, Ankara, Turkey, 16 October 2021, pp.13

  • Publication Type: Conference Paper / Summary Text
  • City: Ankara
  • Country: Turkey
  • Page Numbers: pp.13


During hazelnut processing, a large amount of hard shell and inner skin are generated as waste. Hazelnut skin is a valuable waste as it contains a large amount of polyphenols, which have many health effects, including antioxidant and anticancer properties and the prevention of cardiovascular diseases. The bioaccessibility of polyphenols is important to determine their stability and absorption during gastrointestinal digestion. In this study, total polyphenol (TP) content, antioxidant capacity (AC) and in-vitro digestion of polyphenols (as gastric and intestinal stages) of the extract obtained from hazelnut skin with water were investigated. Gallic and ellagic acids, which are important phenolic compounds of hazelnut skin, were determined by High Performance Liquid Chromatography (HPLC). In addition, the potential use of hazelnut skin extract in noodle production was investigated in order to gain functionality to noodle, which is a widely consumed product. The results showed that hazelnut skin contained 49.00 mg gallic acid equivalent (GAE)/g dry matter (DM) TP and had 62848.57 mmol ascorbic acid equivalent (AAE)/100g DM AC. As a result of HPLC analysis, gallic acid content (20.39 mg/g DM) of hazelnut skin was found to be approximately 5.4 times higher than ellagic acid (3.80 mg/g DM). The stability and AC of the skin polyphenols during in-vitro digestion varied depending on the digestion stage. After the gastric and intestinal stages, the TP content was found to be lower than the initial (before digestion) value. A similar trend was also observed for the AC of the skin extract. It was determined that polyphenols were more stable in gastric stage than in the intestinal one. 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). As in the skin extract, it was observed that the stability of the polyphenols from the noodle sample was higher in gastric stage than intestinal one. The addition of hazelnut skin extract to the noodle dough increased the bioaccessibility of the noodle polyphenols. Therefore, this study showed that hazelnut skin, as an important source of polyphenols, may be useful for food enrichment.

Keywords: Hazelnut Skin, Polyphenol, In-Vitro Digestion, Noodle