The phytochemical profiles for walnuts (J. regia and J. sigillata) from China with protected geographical indications

Abstract

There is little research about walnuts with the certification of protected geographical indications (PGIs), especially about iron walnut. In this study, the comparison of phytochemical profiles for common walnut (Juglans. regia) and iron walnut (Juglans. sigillata) with PGIs was investigated. The results showed that common walnut has advantage in polyunsaturated fatty acids (71.43%), polyphenols (39.65 mg/g), and flavonoids (21.72 mg/g), while iron walnut has advantage in α-tocopherol and γ-tocopherol (22.13 mg/kg and 420.72 mg/kg) and nutritive elements (Mn, Ba, Ni). Additionally, significant differences of palmitoleic acid, arachidic acid, eicosenoic acid, and flavonoids were existed in the two species walnuts, with highest variances of 87.05%. Compared with walnuts in other reports, walnuts with protected geographical indications have a higher level of beneficial fatty acids, especially for monounsaturated fatty acid. Finally, highly positive correlations were observed among amino acids for all analyzed walnuts, and oleic acid was negatively correlated with linoleic acid.