Physico-Chemical and Antioxidant Characteristics in Fruits of Walnut (Juglans regia L.) Genotypes from Inner Anatolia

Abstract

Walnut fruits are used for their nutrition properties for a long time in Anatolia, where seed propagated walnuts are naturally found, as solitary individuals or dense populations. Some relevant physico-chemical and antioxidant characteristics of fruits were determined for fifteen promising walnut (Juglans regia L.) selections (named 'G-1' to 'G-15') propagated from seeds. The well-known Turkish walnut cultivar 'Sebin' was included in the analysis as a standard in order to make comparison with seed propagated genotypes. The average fruit weight and kernel ratios ranged from 7.43 to 12.61 g and 45.10 to 57.83% among the studied genotypes, respectively. The chemical analyses showed that protein, crude oil, ash, carbohydrate and dietary fiber contents of the analyzed walnut genotypes were between 11.09-18.16%, 55.38-65.15%, 1.61-2.08%, 12.01-17.89% and 2.90-4.12%, respectively. Total phenolic content was found between 1,107-1,876 mg GAE/100 g among the genotypes and most of them had higher phenolic content compared with cv. 'Sebin'. The total tocopherols content ranged from 30.0 to 44.4 mg/100 g of the extracted oil. The most common tocopherol in all samples was γ-tocopherol. The results obtained in the hereby study indicated that the seed propagated walnut trees can be very diverse and their nuts have a good potential for valuable sources of phytochemicals.