Hop Extract Research Articles

Characteristics and Antimicrobial Activities of Iron Oxide Nanoparticles Obtained via Mixed-Mode Chemical/Biogenic Synthesis Using Spent Hop (Humulus lupulus L.) Extracts.

Iron oxide nanoparticles (IONPs) have many practical applications, ranging from environmental protection to biomedicine. IONPs are being investigated due to their high potential for antimicrobial activity and lack of toxicity to humans. However, the biological activity of IONPs is not uniform and depends on the synthesis conditions, which affect the shape, size and surface modification. The aim of this work is to synthesise IONPs using a mixed method, i.e., chemical co-precipitation combined with biogenic surface modification, using extracts from spent hops (Humulus lupulus L.) obtained as waste product from supercritical carbon dioxide hop extraction. Different extracts (water, dimethyl sulfoxide (DMSO), 80% ethanol, acetone, water) were further evaluated for antioxidant activity based on the silver nanoparticle antioxidant capacity (SNPAC), total phenolic content (TPC) and total flavonoid content (TFC). The IONPs were characterised via UV-vis spectroscopy, scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS) and Fourier-transform infrared (FT-IR) spectroscopy. Spent hop extracts showed a high number of flavonoid compounds. The efficiency of the solvents used for the extraction can be classified as follows: DMSO > 80% ethanol > acetone > water. FT-IR/ATR spectra revealed the involvement of flavonoids such as xanthohumol and/or isoxanthohumol, bitter acids (i.e., humulones, lupulones) and proteins in the surface modification of the IONPs. SEM images showed a granular, spherical structure of the IONPs with diameters ranging from 81.16 to 142.5 nm. Surface modification with extracts generally weakened the activity of the IONPs against the tested Gram-positive and Gram-negative bacteria and yeasts by half. Only the modification of IONPs with DMSO extract improved their antibacterial properties against Gram-positive bacteria (Staphylococcus epidermidis, Staphylococcus aureus, Micrococcus luteus, Enterococcus faecalis, Bacillus cereus) from a MIC value of 2.5-10 mg/mL to 0.313-1.25 mg/mL.

Effect of Polyphenols on the Ultrastructure of the Dentin Pellicle and Subsequent Erosion

Introduction: Erosive tooth wear is a highly prevalent dental condition that is modified by the ever-present salivary pellicle. The aim of the present in situ study was to investigate the effect of polyphenols on the ultrastructure of the pellicle formed on dentin in situ and a subsequent erosive challenge. Methods: The pellicle was formed on bovine dentin specimens for 3 min or 2 h in 3 subjects. After subjects rinsed with sterile water (negative control), 1% tannic acid, 1% hop extract, or tin/fluoride solution containing 800 ppm tin and 500 ppm fluoride (positive control), specimens were removed from the oral cavity. The erosive challenge was performed on half of the specimens with 1% citric acid, and all specimens were analyzed by transmission electron microscopy. Incorporation of tannic acid in the pellicle was investigated by fluorescence spectroscopy. Results: Compared to the negative control, ultrastructural analyses reveal a thicker and electron-denser pellicle after application of polyphenols, in which, according to spectroscopy, tannic acid is also incorporated. Application of citric acid resulted in demineralization of dentin, but to a lesser degree when the pellicle was pretreated with a tin/fluoride solution. The pellicle was more acid-resistant than the negative control when modified with polyphenols or tin/fluoride solution. Conclusion: Polyphenols can have a substantial impact on the ultrastructure and acid resistance of the dentin pellicle, while the tin/fluoride solution showed explicit protection against erosive demineralization.

α acid fraction from Hop extract exerts an endothelium-derived hyperpolarization vasorelaxant effect through TRPV4 employing the feedforward mechanism of PKCα.

Until now, the beneficial vascular properties of Hop reported in the literature have been mainly attributed to specific compound classes, such as tannins and phenolic acids. However, the potential vascular action of a Hop subfraction containing a high amount of α or β acids remains completely understood. Therefore, this study aims to investigate the vascular effects of the entire Hop extract and to fraction the Hop extract to identify the main bioactive vascular compounds. A pressure myograph was used to perform vascular reactivity studies on mouse resistance arteries. Phytocomplex fractionation was performed on a semi-prep HPLC system and characterized by UHPLC-PDA-MS/MS coupled to mass spectrometry. Western blot analysis was performed to characterize the phosphorylation site enrolled. The entire Hop extract exerts a direct dose-dependent endothelial vascular action. The B1 subfraction, containing a high concentration of α acids, recapitulates the vascular effect of the crude extract. Its vasorelaxant action is mediated by the opening of Transient Receptor Potential Vanilloid type 4 (TRPV4), potentiated by PKCα, and subsequent involvement of endothelial small-conductance calcium-activated potassium channels (SKCa) and intermediate-conductance calcium-activated potassium channels (IKCa) that drives endothelium-dependent hyperpolarization (EDH) through heterocellular myoendothelial gap junctions (MEGJs). This is the first comprehensive investigation of the vascular function of Hop-derived α acids in resistance arteries. Overall, our data suggest that the B1 subfraction from Hop extracts, containing only α acids, has great potential to be translated into the useful armamentarium of natural bioactive compounds with cardiovascular benefits.

Hop (Humulus lupulus L.) extract reverts glycaemic imbalance and cognitive impairment in an animal model of obesity.

The rates of overweight and obesity around the world have increased in past years. The body's adipose tissue stimulates the antioxidant and oxidation imbalance capacity at the cellular level. This scenario favors an inflammatory low-grade systemic condition starting with insulin resistance, which in turn may involve diabetes mellitus type 2 and cognitive decline afterward. Neurological diseases have been correlated to senile age diseases over time. This scenario calls for a change in the incidence of obesity in the younger generation. An unhealthy dietary consumption together with sedentary habits might lead to poor gut absorption of nutrients. Several plants and foods have bioactive compounds that can reduce or inhibit radical scavengers, reactive oxygen species, and metal ion complexes that threaten the cerebral defense system. The bitter acids from hops (Humulus lupulus L.) have been demonstrated to have promising effects on lipid and carbohydrate metabolism improvement, reducing inflammatory responses through alpha acids, beta acids, and analogs action. Therefore, the current study aimed to investigate the bioactivity of hop bitter acids in obese and lean mice. For that, a dry hop extract (DHE) was obtained by applying carbon dioxide as the fluid of supercritical extraction. Afterward, seventy-eight male mice of the C57BL/6J strain were weighed and randomly distributed into six groups of 13 animals each according to the diet offered: (NO) normolipidic diet, (NO1) normolipidic diet containing 0.35% alpha acids, (NO2) normolipidic diet containing 3.5% alpha acids, (HP) hyperlipidic diet, (HP1) hyperlipidic diet containing 0.35% alpha acids, and (HP2) hyperlipidic diet containing 3.5% alpha acids. After applying the glycemic tolerance and insulin tolerance tests, a better stabilization of glycemia levels and weight gain among those animals fed with DHE (NO2 and HP2) were observed in comparison to the obese control group (HP) (p < 0.05). There was also an amelioration of antioxidant capacity observed by checking the enzymatic profile by SOD and an apparent mitigation of brain degeneration by checking GSK3β and p-IRS1 proteins expression (p < 0.05). The y-maze cognitive test applied to highlight possible obesity-harmful animal brains did not indicate a statistical difference between the groups. Although the weekly dietary intake between the obese HP2 group (33.32 ± 4.11, p < 0.05) and control HP (42.3 ± 5.88, p < 0.05) was different. The bioactive compounds present in DHE have demonstrated relevant effects on glycemic control, insulin signaling, and the consequent modulatory action of the obesity-related markers with the brain's inflammatory progression.

Microencapsulation of hop bioactive compounds by spray drying: Role of inlet temperature and wall material

This study explores the effect of spray-drying (SD) inlet temperatures (Tinlet 120 and 150 °C) and wall material on the chemical and physico-chemical properties of microencapsulated hop extracts (MHE). Hop extract was formulated with maltodextrin (MD) and gum Arabic (GA) used in single or in combination with β-cyclodextrin (βCD). MHE were evaluated for physical properties, bitter acids (BA), total polyphenol content (TPC) and encapsulation efficiency (TPC EE), and antioxidant capacity (AOC). Powders produced at Tinlet 150 °C exhibited the highest flowability and generally higher TPC yield. Besides Tinlet, MD enabled the obtaining of MHE with the highest encapsulation efficiency. Other physico-chemical and antioxidant properties differently varied depending on the Tinlet. Overall, the βCD addition positively affected α-acids, and β-acids of MHE obtained at Tinlet 120 °C. ATR-FTIR analysis showed hydrogen bond formation between hop compounds and βCD. Multifactorial ANOVA highlighted that Tinlet, W, and their interaction influenced almost all the chemical and physico-chemical properties of MHE.

Facile green synthesis of wasted hop-based zinc oxide nanozymes as peroxidase-like catalysts for colorimetric analysis.

Hops are a common ingredient in beer production, and a considerable quantity of hops is usually discarded as a waste material once the brewing process is completed. Transforming this waste material into valuable nanomaterials offers a sustainable approach that has the potential to significantly mitigate environmental impact. Herein, a facile and green protocol for the production of zinc oxide nanozymes (ZnO NZs) using wasted hop extract (WHE) as a natural precursor was demonstrated. The process involved a hydrothermal synthesis method followed by a calcination step to form the final ZnO NZs. The results revealed that lupulon, the main β-acid in hops, particularly the phenolic hydroxy group, is primarily responsible for the biosynthesis of ZnO NZs. The WHE-ZnO NZs exhibited exceptional peroxidase-like (POD-like) activity and served as effective catalysts for the oxidation of 3,3,5,5-tetramethylbenzidine (TMB) in the presence of hydrogen peroxide (H2O2). Analysis of the catalytic mechanism revealed that the POD-like activity of these WHE-ZnO NZs originated from their ability to expedite the transfer of electrons between TMB and H2O2, resulting in the enzymatic kinetics following the standard Michaelis-Menten mechanism. Furthermore, we developed a straightforward and user-friendly colorimetric technique for detecting both H2O2 and glucose. By utilizing the WHE-ZnO NZs as POD-like catalysts, we achieved a linear detection range of 1-1000 μM and a limit of detection of 0.24 μM (S/N = 3) for H2O2 detection and a linear range of 0-100 mM and a detection limit of 16.73 μM (S/N = 3) for glucose detection. These results highlighted the potential applications of our waste-to-resource approach for nanozyme synthesis in the field of analytical chemistry.

Investigation of the possibility of hop extract usage in the cheese production

The article presents the results of the use of plant extract from hops in the production of cheese in order to enrich it with antioxidant properties. The main material of the study was hops growing in the Abad region. It was previously shown that the protein content in ordinary hops was 1.7 times less (19%) than in baker's yeast (33%), while the tannin content in ordinary hops was quite high (3.8%). As is known, tannins have anti-ulcer, capillary-strengthening and analgesic properties, which increases the interest of researchers in using ordinary hops as functional properties.The article presents the results of studies of physico-chemical and organoleptic parameters of soft brine cheese. One of the important indicators in determining the quality of raw materials and in choosing them as raw materials for further processing is its physico-chemical properties and organoleptic characteristics. Under laboratory conditions, the results of a study were obtained to determine the physico-chemical parameters, organoleptic quality indicators of soft brine cheese.The safety parameters of hops have been studied in order to produce cheese of guaranteed quality, as well as the physico-chemical composition of raw milk. The stage of application of plant extract is determined - in the process of forming the cheese mass. Studies have also been conducted on the content of vitamin C in various cheese samples with different content of hop extract. The effect of the introduction of hop extract on the organoleptic properties of the product has been studied. It should be noted that the use of plants with antioxidant properties can significantly reduce the rate of oxidative spoilage of dairy products. The obtained results of the study allow us to consider.

Safety Assessment of Hops as Used in Cosmetics.

The Expert Panel for Cosmetic Ingredient Safety (Panel) assessed the safety of Humulus Lupulus (Hops) Extract (reported functions include antimicrobial agent and hair conditioning agent) and Humulus Lupulus (Hops) Oil (reported function is fragrance). The Panel reviewed the relevant data related to these ingredients. Because final product formulations may contain multiple botanicals, each containing the same constituents of concern, formulators are advised to be aware of these constituents and to avoid reaching levels that may be hazardous to consumers. For these ingredients, the Panel was concerned about the presence of 8-prenylnaringenin, β-myrcene, and quercetin in cosmetics, which could result in estrogenic effects, dermal irritation, and genotoxicity, respectively. Industry should use current good manufacturing practices to limit impurities and constituents of concern. The Panel concluded that Humulus Lupulus (Hops) Extract and Humulus Lupulus (Hops) Oil are safe in cosmetics in the present practices of use and concentration when formulated to be non-sensitizing.

β-cyclodextrin versus hydroxypropyl-β-cyclodextrin: is inclusion complexation a suitable alternative to improve the properties of hop-derived β-acids?

Cyclodextrins (CD) are versatile molecules that have been widely studied in several technological areas, as efficient carrier molecules for natural bioactives, through inclusion complexes (IC) formation. The present study aimed to investigate and compare the host:guest interaction between two types of CD (β-cyclodextrin ‘βCD’ and 2-hydroxypropyl-β-cyclodextrin ‘HPβCD’) with a commercial β-acid rich hop extract (βHE), identifying how β-acids properties can be affected by inclusion complexation. Results evidenced that IC formation enhanced β-acids thermal and oxidative stability. Both IC demonstrated great application prospects, however, some differences were observed for the IC structures (observed through DLS, FTIR, XRD, TGA, and SEM analyzes) as well as the properties such as bioctives release, particle stability, antioxidant and antibacterial activities of β-acids. Probably due to a higher content of β-acids on the molecule's outer face, βCD:βHE presented a lower stability, nevertheless, exhibited faster release into meat products simulant solution, along with a higher antibacterial activity.

Анализ состояния и перспектив мировой пивоваренной промышленности и ее влияния на хмелеводческую отрасль

Abstract. The global brewing industry has recently undergone a series of changes, both related to the impact of the coronavirus pandemic (for example, the development of online sales), and based on structural changes caused by changes in consumer demand (reduction in total consumption due to the expansion of various alternative products, growth craft breweries, increased consumption of premium beer, etc.). The authors set a purpose to explore the industry for further use of information in order to establish the impact of new trends in the brewing industry on the hop industry. Methods. The calculations were carried out using the methods of statistical analysis of data from international and Russian official Internet resources. Scientific novelty. The main consumers of hop products are brewers. Accordingly, the identification of trends in the development of the brewing industry will serve as a good information base for making decisions about the direction of development of hop-growing. Results. Taking into account the global trend of accelerated development of craft brewing (China, USA), we can make an unambiguous conclusion about the great prospects for the development of aromatic hop varieties. In China, craft beer consumption is expected to triple by 2025. In the USA, consumers also prefer beer with unique flavors to the already fed up traditional beer drinks. Transnational companies, in turn, are trying to get out of the situation by making their products cheaper. In Brazil and Mexico, the main market share is occupied by subsidiaries of the large transnational company AB InBev. The German market has stabilized for a long time, a small negative dynamics of the market volumes is caused by a large number of alternative drinks. In Russia, beer consumption per person is also decreasing. However, beer sales in value terms continue to grow (mainly due to price growth). As of the beginning of 2022, 70 % of the Russian market was accounted for by transnational companies, which are the main consumers of hop extracts, the production of which is technologically more difficult than the production of hop pellets.

ECHOPvir: A Mixture of Echinacea and Hop Extracts Endowed with Cytoprotective, Immunomodulatory and Antiviral Properties.

Respiratory viral infections continue to pose significant challenges, particularly for more susceptible and immunocompromised individuals. Nutraceutical strategies have been proposed as promising strategies to mitigate their impact and improve public health. In the present study, we developed a mixture of two hydroalcoholic extracts from the aerial parts of Echinacea purpurea (L.) Moench (ECP) and the cones of Humulus lupulus L. (HOP) that can be harnessed in the prevention and treatment of viral respiratory diseases. The ECP/HOP mixture (named ECHOPvir) was characterized for the antioxidant and cytoprotective properties in airway cells. Moreover, the immunomodulating properties of the mixture in murine macrophages against antioxidant and inflammatory stimuli and its antiviral efficacy against the PR8/H1N1 influenza virus were assayed. The modulation of the Nrf2 was also investigated as a mechanistic hypothesis. The ECP/HOP mixture showed a promising multitarget bioactivity profile, with combined cytoprotective, antioxidant, immunomodulating and antiviral activities, likely due to the peculiar phytocomplexes of both ECP and HOP, and often potentiated the effect of the single extracts. The Nrf2 activation seemed to trigger these cytoprotective properties and suggest a possible usefulness in counteracting the damage caused by different stressors, including viral infection. Further studies may strengthen the interest in this product and underpin its future nutraceutical applications.

Preparation and characterization of a solid dispersion of Hexahydrocolupulone and its application in the preservation of fresh apple juice.

Hops extracts and their derivatives have many important biological activities, among them, excellent antibacterial and antioxidant properties make them a promising food preservative. However, poor water solubility limits their application in the food industry. This work aimed to improve the solubility of Hexahydrocolupulone (HHCL) by preparing solid dispersion (SD) and investigating the application of the obtained products (HHCL-SD) in actual food systems. HHCL-SD was prepared by solvent evaporation with PVPK30 as a carrier. The solubility of HHCL was dramatically increased to 24.72mg/mL（25 ℃)by preparing HHCL-SD, much higher than that of raw HHCL (0.002mg/mL). The structure of HHCL-SD and the interaction between HHCL and PVPK30 were analyzed. HHCL-SD was confirmed to have excellent antibacterial and antioxidant activities. Furthermore, the addition of HHCL-SD proved to be beneficial for the sensory, nutritional quality, and microbiological safety of fresh apple juice, hence prolonging its shelf-life.

Antioxidant Activity of Different Hop (Humulus lupulus L.) Genotypes.

The antioxidant activity (AA) of hop extracts obtained from different hop genotypes (n = 14) was studied. For comparison, the purified β-acids-rich fraction and α-acids-with-β-acids-rich fraction were also used to test the antioxidative potential. The AA of purified hydroacetonic hop extracts was investigated using the Ferric Reducing Ability of Plasma (FRAP), Oxygen Radical Absorption Capacity (ORAC) and Intracellular Antioxidant (IA) methods. The FRAP values in different hop genotypes ranged between 63.5 and 101.6 μmol Trolox equivalent (TE)/g dry weight (DW), the ORAC values ranged between 1069 and 1910 μmol TE/g DW and IA potential values ranged between 52.7 and 118.0 mmol TE/g DW. Significant differences in AA between hop genotypes were observed with all three methods. AAs were determined using three different methods, which did not highly correlate with each other. We also did not find significant correlations between AA and different chemical components, which applies both to AA determined using individual methods as well as the total AA. Based on this fact, we assume that the synergistic or antagonistic effects between hop compounds have a more pronounced effect on AA than the presence and quantity of individual hop compounds.

The Influence of Oxidizing and Non-Oxidizing Biocides on Enzymatic and Microbial Activity in Sugarcane Processing

Processing aids are utilized during raw sugar manufacturing at sugarcane processing facilities to mitigate unwanted contamination from microorganisms and their associated exopolysaccharides (EPS). Microorganisms in processing facilities contribute to sugar losses through sucrose inversion and consumption, with many bacteria strains subsequently producing dextran and fructan EPS that can cause downstream issues related to viscosity and crystallization. Similar issues also result from the presence of unwanted starches from plant material in cane juices. Processing aids include biocides for bacterial inhibition, and enzymes (e.g., dextranase, amylase) to break down polysaccharides in juices. However, oxidizing biocide processing aids (e.g., sodium hypochlorite) may inhibit enzymatic processing aid activity. In this study, biocides (sodium hypochlorite, carbamate, and hop extract) and enzymes (dextranase and amylase) were simultaneously added to sugarcane juice to measure residual enzymatic activity for dextranase and amylase. The same biocides were also tested to estimate minimum inhibitory concentrations against bacterial strains isolated from Louisiana sugarcane processing facilities. These experiments provide evidence to suggest that sodium hypochlorite may interfere with enzymatic processing aid activity, with lesser/limited enzymatic inhibition from carbamates and hop extracts. Biocide susceptibility assays suggest that sodium hypochlorite has limited effectiveness against tested bacterial strains. Hop extract biocide was only effective against Gram-positive Leuconostoc while carbamate biocide showed more broad-spectrum activity against all tested strains.

Novel Brazilian hop (Humulus lupulus L.) extracts through supercritical CO2 extraction: Enhancing hop processing for greater sustainability

Hop cultivation has been increasing in the past decade in Brazil, demanding a better understanding of how the processing influences the national hop varieties. Despite the hop process being well-established in the producer countries, there is still room for optimization to reduce energy consumption for a more sustainable process. This study’s main purpose was to understand the influence of drying and supercritical CO2 extraction on the quality of hop extracts. The hop quality during drying was evaluated regarding color, bitter acids, xanthohumol, total essential oil content, and volatile profile. Supercritical CO2 extraction yields, and bitter acid recovery were assessed by HPLC in a range of different temperatures (40 or 60 °C) and pressure (15, 20, 25, or 30 MPa) conditions. Hop processing was optimized to produce a greater extract quality from a Brazilian hop variety, saving energy and solvent consumption, and consequently, reducing the process footprint. Furthermore, this study established supercritical CO2 extraction conditions for Brazilian hop extract production, offering the national beer industry an alternative to overpriced products.

Predictive distribution coefficient (pKD) model for hops extract fractionation in high-pressure CO2 - ethanol - water solvent systems

Predictive distribution coefficient (pKD) model for hops extract fractionation in high-pressure CO2 - ethanol - water solvent systems

Identification of colupulone and lupulone as the main contributors to the antibacterial activity of hop extracts using activity-guided fractionation and metabolome analysis

Hop is widely used in beer brewing and as a medicinal product. The present study comprehensively analyzed the main molecular determinants of the antibacterial activity of hop extracts. Minimum inhibitory concentrations (MIC) against Bacillus subtilis between 31.25 and 250 µg/mL were found in the ethanolic extracts of five hop varieties for beer brewing, but not in the tea hop sample. Activity-guided fractionation revealed the highest antibacterial activity for lupulone and adlupulone (MIC 0.98 µg/mL). Metabolome profiling and subsequent multistep statistical analysis detected 33 metabolites out of 1826 features to be associated with the antibacterial activity including humulone, adhumulone, colupulone, lupulone, and adlupulone. Xanthohumol, the three humulone- and three lupulone congeners were quantified in the hop extracts by a validated ultrahigh-performance liquid chromatography–mass spectrometry method. Considering concentrations and MICs, colupulone and lupulone were identified as major contributors to the antibacterial activity of hop extract with the highest antibacterial activity values (concentration/MIC) of 1.59 and 2.56.

Chemical compositions and sleep-promoting activities of hop (Humulus lupulus L.) varieties.

Among natural products with sleep-promoting activity, hops have been used since ancient times as a tranquilizer and hypnotic agent. This study investigated the sleep-promoting effects of extracts of various hop (Humulus lupulus L.) varieties in invertebrate and vertebrate models. The content of α-acids, β-acids, and xanthohumol was higher in hop 70% alcohol extracts than in hop hot water extracts. Among the alcohol extracts, Citra contained a high α-acid content (229.32µg/mg), while Saphir showed high β-acid and xanthohumol content (66.37 and 4.23µg/mg, respectively). In Drosophila melanogaster, Simcoe and Mosaic water extracts and Saphir and Simcoe alcohol extracts significantly increased total nighttime sleep. Total sleep time of mice with pentobarbital-induced sleep was significantly increased by Simcoe and Mosaic water extracts and Saphir and Simcoe ethanol extracts compared to the normal group. Oral administration of Simcoe water extract and Saphir alcohol extract improved sleep in the caffeine-induced insomnia model and upregulated the mRNA expression of GABAA (gamma 2 subunit) and GABAB receptors in mouse brains. Additionally, Saphir alcohol extract significantly increased the GABA content in mouse brains. Simcoe water extract and Saphir ethanol extract modulated GABAergic signaling to improve sleep-related behaviors, including sleep duration.

Extraction of hops pelletized (Humulus lupulus) with subcritical CO2 and hydrodistillation: Chemical composition identification, kinetic model, and evaluation of antioxidant and antimicrobial activity

Hop essential oil and hop extract using carbon dioxide (CO2) are products with high added value because they have bioactive and sensory properties. In this context, the objective of this study was to obtain and characterize essential oil and extracts from pelleted hops of El Dorado, Polaris, Hallertau Blanc and Callista varieties using hydrodistillation and subcritical CO2 extraction methods. Extraction yield ranged from 0.38 % to 1.97 % (m/m) for essential oils and from 8.76 % to 15.35 % (m/m) for extracts using subcritical CO2. The chemical compositions of the essential oils were mainly monoterpene (18.14 % to 29.91 %) and sesquiterpene (46.01 % to 59.03 %) hydrocarbons and for the extracts were sesquiterpene hydrocarbons (33.05 % to 71.90 %) and oxygenated sesquiterpenes (14.80 % to 34.89 %). The extracts showed better antioxidant activity than essential oils due to the presence of phenolic compounds and flavonoids. Hop extracts showed some antimicrobial activity, but essential oils did not demonstrate antimicrobial potential. Hop extracts obtained with subCO2 have the potential to be used in the brewing industry as a flavoring and as natural antioxidants.

Conventional and innovative extraction technologies to produce food-grade hop extracts: Influence on bitter acids content and volatile organic compounds profile.

Hop extracts represent a natural alternative to synthetic food additives because of their high content of bitter acids and volatile organic compounds (VOCs) with bittering, flavoring, and antimicrobial properties. However, broader uses of hop extracts as natural techno-functional ingredients rely on the identification of sustainable and affordable extraction technologies allowing to diversify the processes and produce extracts characterized by different compositions and, consequently, qualitative properties. Thus, this study is aimed to evaluate and compare the effect of innovative and conventional extraction methods on the bitter acids content and VOCs pattern of food-grade ethanolic hop extracts for food applications. Innovative extractions were carried out by using two ultrasound systems (a laboratory bath [US] and a high-power ultrasound bath [HPUS]), and a high-pressure industrial process (high hydrostatic pressure [HHP]). Conventional extractions (CONV) were performed under dynamic maceration at 25 and 60°C; for ultrasound and conventional methods, the effect of the extraction time was also investigated. Among the extracts, the highest and lowest content of bitter acids was found in CONV 60°C extracts, and HHP and CONV 25°C extracts, respectively. Of the 34 VOCs identified in dry hops, ∼24 compounds were found in US, HPUS and CONV extracts, while only 18 were found in HHP. CONV extractions showed higher selectivity for sesquiterpenes, while US and HPUS showed higher selectivity for esters and monoterpenes. Hierarchical cluster analysis (HCA) and partial least squares-discriminant analysis (PLS-DA) allowed classifying hop extracts based on the extraction methods and also allowed highlighting the technological conditions to produce hop extracts with specific techno-functional and flavoring properties. PRACTICAL APPLICATION: The study showed that different extraction methods can lead to hop products with varying sensory and functional properties. By selecting the right extraction method, companies can produce hop extracts with specific compositions that meet their needs for clean label and sustainable food products, as well as new edible packaging or coatings.