Nutritional composition of domestic and imported walnuts (Juglans regia L.)

Abstract

This study was investigated to compare the nutritional composition of walnuts (Juglans regia L.) between domestic cultivars such as Gimcheon 1ho, Geumgok, and Geumreung as well as imported cultivars from China and the USA. In the free sugar analysis, glucose and maltose were detected. The highest glucose content was found in Geumgok. The highest maltose content was found in Gimcheon 1ho. Linoleic acid and oleic acid were detected as major fatty acids in all walnuts. Total fatty acid contents were the highest in the USA cultivar. However, the ratio of polyunsaturated fatty acid to total fatty acid of the Geumgok and USA cultivars were 54.73% and 49.35%, respectively. Further, a-linolenic acid was only detected in walnuts of the Geumgok and USA cultivars. As a result of the analysis of inorganic components, sodium, sulfur, potassium, magnesium, and phosphorous were detected as major components of walnuts. Major amino acids such as aspartic acid, glutamic acid, and arginine were detected in walnuts. γ-Tocopherol was detected as a major tocopherol in walnuts, and it constituted the highest contents in Gimcheon 1ho and USA in domestic and imported cultivars, respectively. Finally, 60% ethanolic extract of Geumgok had the highest total phenolic and total flavonoid contents. Therefore, these results suggest that domestic Korean cultivars of walnuts are nutritionally competitive when compared with imported walnuts and should be available as high value-added income crop. ? 2020 Korean Society of Food Science and Nutrition. All rights reserved.