Polyphenols in white and green shoots of cultivated hop (Humulus lupulus L.)

Čeh, Barbara (author), Karničnik Klančnik, Ana (author), Poklar Ulrih, Nataša (author)

Green and white hop shoots are routinely removed during hop production and represent an underutilized biomass stream with potential for valorization. This study evaluated the biomass yield and polyphenolic composition of shoots from three cultivated hop varieties, Aurora, Celeia, and Styrian Wolf. White and green shoots were sampled in 2021, while green shoots were additionally sampled in 2023. Total phenolics were determined by the Folin–Ciocalteu method, and individual polyphenols were quantified by HPLC. Green shoot biomass removed during training differed significantly among varieties, ranging from 76 kg/ha in Aurora to 188 kg/ha in Styrian Wolf. Total phenolic content of green shoots ranged from 2.22 to 3.47 mg CAE/g dry matter, with Styrian Wolf showing the highest value. Polyphenolic profiles differed markedly between shoot types: white shoots contained higher concentrations of catechin, epicatechin, and naringin, whereas green shoots contained quercetin, higher ferulic acid levels, and the hop-specific prenylflavonoid xanthohumol. Interannual variation was compound-specific at green shoots: the wet ter February–April period in 2021 coincided with higher epicatechin and ferulic acid concentrations, whereas naringin and 4-hydroxybenzoic acid were higher in the drier 2023 February–April period. Compared with commonly consumed polyphenol-rich foods, hop shoots contained relatively low concentrations of individual polyphenols; however, their routine generation as an agricultural side stream may make them an attractive raw ma terial for selective recovery of specific compounds, particularly hop-specific xanthohumol.

• Language: English
• Keywords: white hop shoots, green hop shoots, waste plant biomass, circular economy, polyphenols, catechin, epicatechin, naringin, rutin, quercetin, xanthohumol, ferulic acid, 4-hidroxybenzoic acid
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: BF - Biotechnical Faculty
• Publication status: Published
• Publication version: Version of Record
• Publication date: 01.01.2026
• Year: 2026
• Number of pages: 17 str.
• Numbering: Vol. 16, Iss, 17, art. 1685
• PID: 20.500.12556/RUL-187766
• UDC: 633.791:631.57:547.56
• ISSN on article: 2073-4395
• DOI: 10.3390/agronomy16171685
• COBISS.SI-ID: 289760003
• Publication date in RUL: 14.09.2026

Record is a part of a journal

• Title: Agronomy
• Shortened title: Agronomy
• Publisher: MDPI AG
• ISSN: 2073-4395
• COBISS.SI-ID: 522953241

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.

Secondary language

• Language: Slovenian
• Keywords: hmelj, Humulus lupulus L., beli hmeljevi poganjki, zeleni hmeljevi poganjki, stranski proizvodi, odpadna rastlinska biomasa, polifenoli