Effects of Pretreatment and Drying on the Volatile Compounds of Sliced Solar-Dried Ginger (Zingiber officinale Roscoe) Rhizome

Ginger (Zingiber officinale Roscoe) rhizomes are mostly used as spice and medicine due to their high aroma intensity and medicinal bioactive compounds. However, the volatile compounds of ginger, partly responsible for its aroma and medicinal properties, can be affected by the pretreatment, drying method, and extraction processes employed. The objective of this study was to assess the effects of pretreatment and drying on the volatile compounds of yellow ginger variety at nine months of maturation. The effect of potassium metabisulfite (KMBS) and blanching pretreatment and drying on the volatile compounds of ginger using head space solid-phase microextraction with GCMS/MS identification (HS-SPME/GCMS/MS) was investigated. KMBS of concentrations 0.0 (control), 0.1, 0.15, 0.2, and 1.0% and blanching at 50°C and 100°C were used for pretreatment and dried in a tent-like concrete solar (CSD) dryer and open-sun drying (OSD). The different concentrations of KMBS-treated fresh ginger rhizomes did not result in any particular pattern for volatile compound composition identification. However, the top five compounds were mostly sesquiterpenes. The 0.15% KMBS-treated CSD emerged as the best pretreatment for retaining α-zingiberene, β-cubebene, α-farnesene, and geranial. The presence of β-cedrene, β-carene, and dihydro-α-curcumene makes this study unique. The 0.15% KMBS pretreatment and CSD drying can be adopted as an affordable alternative to preserve ginger

Antifungal activity of hop extracts and compounds against the wheat pathogen Zymoseptoria tritici

International audienceSearching for alternative methods to conventional pesticides against crop pathogens is a huge challenge. Here, we tested the potential of hop extracts and compounds to be used as biofungicides towards Zymoseptoria tritici, the most frequently-occurring and damaging pathogen on wheat crops. Hop (Humulus lupulus L.) is known for its benefits on human health conferred by its antifungal, antiviral and antibacterial properties. However, this species has never been examined for its ability to biocontrol phytopathogens. Hydro-alcoholic crude extracts from different parts of hop (leaves, stems, rhizomes, and female cones also called hops), as well as hops essential oil, were assessed for their activity against Z. tritici using spotting bioassays on PDA medium. Moreover, the major phenolic compounds purified from the hydro-alcoholic extract of hops following a bioguided fractionation and the three major terpenes of hops essential oil, previously characterized by GC-MS, were also tested using a microdilution method. Furthermore, checkerboard method was used to assess the potential co-action of hops essential oil and the synthetic fungicide bixafen. Dose-response-curves revealed that only the crude extract and the essential oil from hops significantly decreased fungal growth. Among the purified prenylated chalcones and acylphloroglucinol derivatives, only des-methylxanthohumol and co-humulone showed an antifungal activity against Z. tritici with a half-maximal inhibitory concentration of 0.2 and 0.11 g L-1 respectively. The three major terpenes of hops essential oil were not active but an additive to synergistic effect was observed when the essential oil is combined to bixafen. This study provides new insights into the valorization of antimicrobial properties of hop in crop protection

Hop (Humulus lupulus L.) Specialized Metabolites: Extraction, Purification, Characterization in Different Plant Parts and In Vitro Evaluation of Anti-Oomycete Activities against Phytophthora infestans

Botanicals represent a promising source of metabolites in the search for new biofungicides. In this context, this study aimed at evaluating the in vitro anti-oomycete activity of hop (Humulus lupulus L.) extracts and metabolites against Phytophthora infestans, an oomycete causing late blight disease in Solanaceae. Crude hydro-ethanolic extracts and dichloromethane sub-extracts of different parts (cones, leaves, stems and rhizomes) were characterized by UHPLC-UV–MS and some cone specialized metabolites were purified by CPC and preparative HPLC. A commercial hop cone essential oil was also analyzed by GC–MS. All extracts succeeded in inhibiting mycelial growth and spore germination with morphological alteration of the mycelium. Extracts of leaves showed a significant anti-oomycete activity compared to the extracts of cones, stems, and rhizomes. Moreover, no difference was noticed between the crude hydro-ethanolic extract and the dichloromethane sub-extract activity, except for leaves, with the apolar sub-extract being more active than the crude one. The extracts of cones succeeded in inhibiting more P. infestans than the essential oil, which appeared to be the less active evaluated modality. Some purified prenylated phenolic compounds also inhibited P. infestans although copper sulfate, a mineral fungicide control, was still more active. This study highlights the potential use of hop by-products as biofungicides to manage P. infestans

Phytochemical characterisation and aromatic potential for brewing of wild hops (Humulus lupulus L.) from Northern France: Towards a lead for local hop varieties

peer reviewedIn the current context of developing aromatic beers, our study aims at deciphering the chemical characterisation of cones from 39 wild hop genotypes collected in the North of France and replanted in an experimental hop farm, as well as 10 commercial and 3 heirloom varieties, using HS-SPME/GC–MS for the volatile compounds, UHPLC-UV for phenolic compound quantification, and UHPLC-IMS-HRMS for untargeted metabolomics. These analyses revealed a strong opposition between wild accessions and reference varieties, and an original chemical composition of some genotypes. 27 beers were produced with the same recipe, analysed by SBSE-GC–MS and evaluated by panellists. The unique difference relates to the hops to be assessed in order to determine their sensory profile. The different datasets were compared by OPLS-DA analysis in order to identify chemical markers which may influence the hop aromatic potential. Our results highlight the aromatic potential of some wild accessions, close to the commercial variety Cascade