Biochemical characterization and antioxidant activity of walnut kernel (Juglans regia L.) of accessions from Middle and High Atlas in Morocco

Resumo

Biochemical composition and antioxidant activity were determined in kernel nuts for eleven Moroccan walnut (Juglans regia L.) accessions representing its main cropping area. Total oil, carbohydrates, crude protein, energy value, crude fiber and flavonoid have varied significantly between accessions, respectively within the range values of 54.50-65.48%, 8.17-19.25%, 11.5-25.58%, 648.91-713.83 Kcal, 4.17-6.75% and 12.59-62.11mg RE 100 g^-1 DM.  Besides, mineral composition (mg 100 g^-1) of kernel have varied also significantly among accessions and particularly for phosphorus (338.1-675.87), copper (2.08-6.67), zinc (3.39-18.63), iron (1.17-2.64), chromium (0.16-0.20), nickel (1.26-1.45) and boron (0.07-1.49). However, dry matter (96.75-98.56%), moisture (1.44-3.24%), ash (1.67-2.53%), total phenols content (1017-3739 mg GAE 100 g^-1 DM), DPPH radical scavenging activity (75.02-85.96%), potassium (210.10-338.93 mg 100 g^-1), magnesium (79.15-374.54 mg 100 g^-1), sodium (1.17-12.63 mg 100 g^-1) and manganese (0.79-1.67 mg 100 g^-1) did not show significant variations between accessions. Furthermore, the results showed that Moroccan walnut constitutes an important source of nutrient elements, essentially fat, carbohydrates, protein, phosphorus and zinc, and natural antioxidants, phenolic compounds. Accordingly, consumption of all studied kernels accessions would be beneficial to health. This study showed considerable biochemical variation between the analyzed walnut accessions, which could help to select genotypes with desired traits according to their chemotypes.