Nutritional composition and antioxidant activity of different walnut varieties (Juglans regia L.) from Nerpio (Spain) in comparison to commercial varieties

Abstract

In the Nerpio region (Albacete, Spain), endogenous walnut cultivars have been grown since ancient times. None of them has been chemically characterized to valorize them in comparison to commercial varieties. In this work, 47 native (N) and 7 foreign (F) walnut cultivars grown in Nerpio, and 13 commercial (C) samples were studied during three seasons. The average yield, moisture, and protein and oil contents were slightly lower in the N samples than in C. The composition of fatty acid suggested that the N walnuts could be more stable against oxidation due to their higher amount of MUFA and lower amount of PUFA. The biological protein value for the samples was similar but the antioxidant capacity marked important differences among them: N cultivars reached the highest scores, with intermediate F values. Local walnut varieties from Nerpio should be valorized on the basis of their potentially enhanced health benefits, although further studies must be developed on their phytochemicals.