Chemical Composition, Antioxidant Capacity And Total Phenolic Content of Hazelnuts Grown In Different Countries

Abstract

Hazelnut providing the macro-and micronutrients is a constituent of the healthy diet. Hazelnut, one of the most consumed treenut, is produced in the different countries. The geographical origin influences the chemical composition and the biological activity in the several plant foods. The purpose of this study is to evaluate the chemical composition, the antioxidative capacity and total phenolic content of the hazelnut kernels obtained from the different countries, including Azerbaijan, Chile, Italy, and Turkey. The hazelnut kernels were examined for crude oil, ash, moisture, and protein contents. The refractive index, iodine value, and fatty acid composition of the hazelnut oils were identified. In addition, the hazelnut oil, the kernels, and the defatted kernels were tested for their antioxidative activities and total phenolic contents. Protein contents of the hazelnuts from different countries were similar. The largest oil yield was determined in the hazelnut kernels from Chile and Turkey (62.35 ± 0.51 % and 62.29 ± 0.46 %, respectively). While the oil from Turkish hazelnut kernels showed the highest oleic acid content (84.09 ± 0.17 %), Azerbaijan hazelnut oil had the lowest oleic acid content (78.10 ± 0.48). The highest phenolic content was detected in the hazelnut kernels from Azerbaijan. Although the lowest phenolic content was observed in the hazelnut kernels from Turkey, the most potent antioxidative capacity was determined in the Turkish hazelnut kernels, their oil, and their defatted form. It can be concluded that the Turkish hazelnut kernels could contain high amounts of the fat-soluble antioxidants in addition to the water-soluble phenolic antioxidants. The results suggested that the hazelnuts exhibited different chemical composition, antioxidant capacity, and phenolic content depending on their origin.