Antioxidant properties, profile of polyphenolic compounds and tocopherol content in various walnut (Juglans regia L.) varieties
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The aim of this work was to characterize antioxidant properties, establish the profile of polyphenolic compounds and evaluate the content of tocopherols in walnut fruits. The research material consisted of eleven walnut varieties which were examined for dry matter content, fats and minerals content. Their antioxidant capacity was determined by the ABTS, DPPD and FRAP assays. The profile of polyphenolic compounds was established by means of ultra-high performance liquid chromatography coupled with a mass detector (UPLC–PDA–ESI–MS). In addition, tocopherols (α, β, γ and δ) were quantified using high-pressure liquid chromatography (HPLC). Walnut fruits differed significantly in terms of their physicochemical parameters, antioxidant properties and the content of bioactive compounds. Walnuts of the Lake cultivar exhibited the strongest antioxidant potential, while those of the U02 had the highest content of total polyphenols (2.07 g/100 g). Phenolic acids, among which gallic acid, protocatechuic acid, syringic acid, and genistinic acid were identified, dominated in the polyphenol profile. In turn, the spectrum of tocopherols contained four isoforms: α, β, γ and δ. In the examined walnuts, the total tocopherol content ranged from 19.83 mg/kg (U17) to 126.00 mg/kg (Lake) and β- and δ-tocopherols were present in major quantities.
KeywordsWalnuts Antioxidant properties Polyphenols Tocopherols
Compliance with ethical standards
Conflict of interest
The authors have declared no conflict of interests.
Compliance with ethics requirements
This article does not contain any studies with human and animal subjects.
- 2.FAO (2008) Food and Agriculture Organisation, RomeGoogle Scholar
- 7.Pereira JA, Oliveira I, Sousa A, Valentăo P, Andrade PB, Ferreira ICFR, Ferreres F, Bento A, Seabra R, Estevinho L (2007) Walnut (Juglans regia L.) leaves: phenolic compounds, antimicrobial activity and antioxidant potential of different cultivars. Food Chem Toxicol 45:2287–2295CrossRefGoogle Scholar
- 10.AOAC. Official Methods of Analysis of AOAC International, 17th ed.; Horwitz, W., Ed.; AOAC: Arlington, VA, 2000; Vol. II, 40, 1–3Google Scholar
- 17.Li L, Tsao R, Yang R, Karmer JK, Hernandez M (2007) Fatty acid profiles, tocopherol contents, and antioxidant activities of heartnut (Juglans ailanthifolia Var. cordiformis) and Persian Walnut (Juglans regia L.). J Agric Food Chem 55:1164:1169Google Scholar
- 18.Bolling BW, Chen C-YO, McKay DL, Blumberg JB (2011) Tree nut phytochemicals: composition, antioxidant capacity, bioactivity, impact factors. A systematic review of almonds, Brazils, cashews, hazelnuts, macadamias, pecans, pine nuts, pistachios and walnuts. Nutr Res Rev 24(02):244–275CrossRefGoogle Scholar