Geographical Origin Affects the Nut Traits, Bioactive Compounds, and Fatty Acid Composition of Turkish Hazelnut Cultivars (Corylus avellana L. cvs. Çakıldak, Palaz, and Tombul)

Hazelnuts are valuable for human health and nutrition. They are also an economically important type of nut. This study was conducted to determine the effect of different geographical origins (Giresun, Ordu, and Samsun/Türkiye) on the nut characteristics, bioactive compounds, and fatty acid composition of three hazelnut cultivars (cvs. Çakıldak, Palaz, and Tombul). The highest nut and kernel weights and sizes were determined to be in all cultivars in Samsun. The highest kernel ratio was recorded in the Çakıldak and Palaz cultivars grown in Giresun. However, shell thickness was not affected by geographical origin. The highest levels of total phenolics and total flavonoids were recorded in all cultivars in Samsun. The antioxidant activity of the cultivars differed according to geographical origin. The highest oleic acid was found in all cultivars in Giresun, while the highest linoleic acid was observed in those grown in Ordu. Generally, the highest results in terms of other fatty acids were recorded in all cultivars in Samsun. According to the results of the principal component analysis (PCA), the cultivars grown in the Samsun region were generally related to better nut traits and phenolics, while the cultivars grown in the Giresun and Ordu regions were associated with better antioxidant activity and fatty acid composition. This study shows that the nut traits, bioactive compounds, and fatty acid composition of hazelnuts are affected by geographical differences. These results provide valuable insights for hazelnut growers and the food industry.