Walnut (J. regia) agro-residues as a rich source of phenolic compounds

Medič, Aljaž (author), Jakopič, Jerneja (author), Solar, Anita (author), Hudina, Metka (author), Veberič, Robert (author)

The present study was designed to identify and quantify the major phenolic compounds (phenolics) in the inner and outer husks, buds and bark of the Persian walnut, Juglans regia L. A comparison across six different cultivars grown in Slovenia was also carried out: ‘Fernor’, ‘Fernette’, ‘Franquette’, ‘Sava’, ‘Krka’ and ‘Rubina’. A total of 83 compounds were identified, which included 25 naphthoquinones, 15 hydroxycinnamic acids, 8 hydroxybenzoic acids, 13 flavanols, 2 flavones, 1 flavanone and 19 flavonols. For the first time, 38 phenolics in the husks, 57 phenolics in the buds and 29 phenolics in the bark were presented in J. regia within this study. Naphthoquinones were the major phenolics determined, approximately 75% of all analysed phenolics in the inner husk, 85% in the outer husk, 50% in buds and 80% in bark. The highest content of phenolics was found in the walnut buds, followed by the bark, the inner husk and the outer husk. On the basis of these high phenolic contents, walnut husks, buds and bark represented valuable by-products of the walnut tree. These data also show origin-related phenolic contents across the cultivars, and thus these phenolic profiles might serve to define the origins of different walnut cultivars.

• Language: English
• Keywords: hydrojuglone, juglone, naphthoquinones, phenolic compounds, 1, 4–naphthoquinone, bark, buds, husk
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: BF - Biotechnical Faculty
• Publication status: Published
• Publication version: Version of Record
• Year: 2021
• Number of pages: 24 str.
• Numbering: Vol. 10, iss. 6, art. 535
• PID: 20.500.12556/RUL-135592
• UDC: 634.1/.7
• ISSN on article: 2079-7737
• DOI: 10.3390/biology10060535
• COBISS.SI-ID: 67153667
• Publication date in RUL: 21.03.2022

Record is a part of a journal

• Title: Biology
• Shortened title: Biology
• Publisher: MDPI
• ISSN: 2079-7737
• COBISS.SI-ID: 523004441

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.
• Licensing start date: 15.06.2021

Secondary language

• Language: Slovenian
• Keywords: oreh, Juglans regia, lupina, fenolne spojine

Projects

• Funder: ARRS - Slovenian Research Agency
• Project number: P4-0013
• Name: Hortikultura