Fatty acid composition, phenolic compound content and antioxidant activity of unique walnut genotypes with red seed coat

Abstract

The objective of the present work was to study total oil, fatty acid, tocopherol, total phenol, phenolic compound content and antioxidant activity of unique walnut genotypes with red-coloured seed coat. Seven red walnut genotypes plus ‘Chandler’ as a standard cultivar were selected as plant materials for the work. The total oil content of the geno-types ranged from 409.44 g·kg-1 to 567.87 g·kg-1. Fatty acids from walnut kernel oil were mostly composed of myristic, myristoleic, palmitic, oleic, linoleic and linolenic acids, linoleic acid being dominant. Tocopherol contents varied among the genotypes-α-tocopherol from 1.18 mg·kg-1 to 15.25 mg·kg-1, β-+ γ-tocopherol from 154.76 mg·kg-1 to 331.27 mg·kg-1 and δ-tocopherol from 3.24 mg·kg-1 to 45.86 mg·kg-1. Total phenolics content ranged from 118.12 mg·kg-1 to 169.6 mg·kg-1 (expressed as gallic acid equivalent). Antioxidant capacity was found between 68.2 % and 69.8 %. Contents of phenolics, namely, gallic acid, catechin, caffeic acid, syringic acid, p-coumaric acid, rutin trihydrate, ellagic acid, quercetin, naringin and juglone varied greatly among genotypes. The results indicate that red walnut variants are a great source of oils, fatty acids, tocopherols and phenolics, having good antioxidant potential as well. © 2020 National Agricultural and Food Centre (Slovakia).