Food Research Institute

Ozcan, A. – Sutyemez, M. – Attar, S. H. – Kafkas, E. – Ergun, M.
Fatty acid composition, phenolic compound content and antioxidant activity of unique walnut genotypes with red seed coat
Journal of Food and Nutrition Research, 59, 2020, No. 4, s. 352-360

Muharrem Ergun, Department of Horticulture, Bingol University, 12100 Bingol, Turkey. E-mail: muharem.ergun@yahoo.com

Received 9 June 2020; 1st revised 18 September 2020; 2nd revised 22 October 2020; accepted 4 November 2020; published online 4 December 2020.

Summary: 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 genotypes 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 - alpha-tocopherol from 1.18 mg·kg^-1 to 15.25 mg·kg^-1, beta- + gamma-tocopherol from 154.76 mg·kg^-1 to 331.27 mg·kg^-1 and delta-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.

Keywords: red walnut; walnut pellicle; phenolic compounds; ellagic acid; fatty acids; tocopherols

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