Fatty acid and phytosterol contents in hazelnut (Corylus avellana L.) varieties grown in different regions: A comparative study of functional properties

Hazelnuts (Corylus avellana L) are among the most consumed nuts worldwide due to their high nutritional value and distinctive aroma. Hazelnuts are considered functional foods because of their nutritional and nutraceutical properties. The oils, fatty acids, phenolic compounds, and phytosterols they contain make them ideal for functional food production. The region and environmental conditions where hazelnuts are grown influence their chemical characterization and biological value. Many studies have been conducted on the nutritional composition of hazelnuts. However, no comprehensive study has been conducted on the effects of regional differences on the functional properties of cultivars. This study focused on determining the effects of regional differences on the functional properties of eight hazelnut cultivars grown most intensively in three different hazelnut-growing regions of Turkey (the Eastern Black Sea, Middle Black Sea, and Western Black Sea regions). The results were statistically evaluated at a confidence interval of p<0.05. As a result of comprehensive physicochemical analyses, it was determined that the oil contents of hazelnut varieties varied between 60.28±1.54% and 65.43±0.60%, and the iodine values varied between 92.43±1.74% and 95.35±2.81%, and these changes were found to be significant according to p<0.05. Regional differences were observed, especially in fatty acid compositions, notably oleic acid (C18:1) at 74.10±2.03% - 78.55±2.02% and linoleic acid (C18:2) at 12.18±1.52% - 16.12±1.85%. The phytosterol composition ranged from ß-sitosterol at 59.13±8.29% - 81.65±3.14% and stigmasterol at 6.89±0.86% - 12.50±7.25% (p<0.05), and shows that regional and variety differences also have a significant effect on phytosterol composition. In conclusion, when the data is evaluated holistically, it has been determined that while the functional composition of hazelnuts varies depending on the variety (genetic origin), the growing region conditions also have a significant effect on the functional composition. Furthermore, the data obtained will contribute to the correct sourcing of the most suitable raw materials according to variety and region in the food industry, where hazelnuts and hazelnut products are widely used.