Comparison of α and ß-acid isomerization in hops and beer using HPLC, confocal microscopy, spectrofluorimetry and chemical analysis of metabolites and essential oils in flowers of different hop cultivars produced in Brazil.

We used confocal microscopy and spectrofluorescence to characterize the emission spectra in hop flowers, to follow the isomerization processes in different hop preparations, and beers, to compare with HPLC extracted samples. Flowers of different hop cultivars produced in three regions of Brazil, were quantitated by HPLC and GC-MS. The fluorescence spectra showed two characteristic emission bands evaluated from different preparations. The isomerization process leads to a gradual decrease in fluorescence intensity as the reaction progresses. This demonstrates the valuable use of confocal microscopy and fluorescence spectroscopy for analysis of the correlation between bitter acid indices with fluorescence intensity and lifetime microscopy. Such techniques can be used directly in the flowers allowing rapid monitoring of the brewing process. Twenty-nine substances were characterized in the essential oils and some cultivars presented quantities of bitter acids and essential oil levels close to those expected for plants after more than three years of cultivation.

Unlocking hot trub's potential: a simple method for extracting bitter acids and xanthohumol.

BACKGROUND: Hot trub is a macronutrient- and micronutrient-rich by-product generated in the brewing industry, which is still underrated as a raw material for reprocessing purposes. In this context, this study aimed to investigate the extraction of bitter acids' and xanthohumol from hot trub as well as identify the significance of parameters for the process. The research assessed various extraction parameters, such as pH, ethanol concentration, temperature, and solid-to-liquid ratio, using a Plackett-Burman design. RESULTS: Ethanol concentration and pH were the most significant parameters affecting extraction yield. ß-acids were found to be the principal components of the bitter acids, with a maximum concentration near 16 mg g-1, followed by iso-α-acids and α-acids achieving 6 and 3.6 mg g-1, respectively. The highest yields of bitter acids were observed in the highest ethanol concentration, while pH was relevant to extraction process in treatments with low ethanol ratios. Concerning the xanthohumol extraction, the approach achieved maximum concentration (239 µg g-1) in treatments with ethanol concentration above 30%. Despite their variances, the phytochemicals exhibited comparable extraction patterns, indicating similar interactions with macromolecules. Moreover, the characterization of the solid residues demonstrated that the extraction process did not bring about any alterations to the chemical and total protein profiles. CONCLUSION: Ethanol concentration was found to have the most significant impact on the extraction of bitter acids and xanthohumol, while temperature had no significant effect. The solid remains resulting from the extraction showed potential for use as a protein source. © 2024 Society of Chemical Industry.

Bitter acids from hydroethanolic extracts of Humulus lupulus L., Cannabaceae, used as anxiolytic

Humulus lupulus L., Cannabaceae, é usada como sedativo e ansiolítico na medicina popular. O método de HPLC-DAD-ESI-MSn representa uma ferramenta poderosa para a análise de produtos naturais, desde que ela fornece o espectro de UV e informações estruturais sobre os constituintes da mistura. O objetivo deste trabalho foi o de caracterizar os constituintes encontrados no extrato hidroalcoólico. Os constituintes 1-9 foram tentativamente caracterizados através do UV/DAD e ionização por electrospray (MS/MS) depois da separação usando fase reversa, tempo de retenção e dados da literatura. Os principais compostos fenólicos (baseados na área dos picos) foram caracterizados como ácido hulupínico (9), coulupona (8), dois alfa-ácidos amargos oxidados (principais constituintes), um deles sendo um derivado da coumulinona oxidada (5) e o outro um derivado da humulinona oxidada (7), junto com uma procianidina B (3) e os flavonoides rutina (4) e o canferol-7-O-rutinosídeo (6). Esta planta conhecida devido às suas propriedades ansiolíticas e por ser um componente da cerveja, mostrou derivados oxidados de alfa-ácidos, como principais constituintes do extrato hidroalcoólico.

Humulus lupulus L., Cannabaceae, is commonly used as light sedative and anxiolytics in folk medicine. HPLC-DAD-ESI-MSn represents a powerful tool for the analysis of natural products, since it can simultaneously provide a UV chromatogram and significant structural information about compounds in complex mixture. The aim of this work was characterize the constituents present in hydroethanolic extract. Compounds 1-9 were tentatively characterized on the basis of UV, MS/MS, after reversed phase separation, retention time and literature data. The main phenolic compounds (based on peak area) were characterized as hulupinic acid (9), cohulupone (8), two oxidized hop alfa-bitter acids (principal constituents), one being a oxidized cohumulinone (5) and the other an oxidized humulinone (7) derivatives, together with a procyanidin dimer B (3), flavonoids rutin (4) and kaempferol-7-O-rutinoside (6). This plant known, due to anxiolytic property and beer flavoring, showed oxidized hop bitter acids, as principal constituents, in its hydroethanolic extract.