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•Hop is an important ingredient for brewing mainly due to its bitterness and aromatic flavor features.•Humulones and Lupulones, also known as - and -acids, are some of the most ...valuable hop compounds.•High performance liquid chromatography is the most used separation technique for bitter acids determination.•Capillary electrophoresis has emerged as a faster and greener alternative to chromatography for bitter acids determination.•Analytical methods for hop acids determination, by LC and CE, are summarized and discussed.
Hop plays an essential role in brewing beer and its study and analysis is of paramount importance. - and -acids are considered two of the most important hop components. While -acids are associated with the bitter flavor, -acids have antimicrobial effects. This work aims to critically review the published analytical methods for - and -acids determination in hops employing separation methods in liquid medium: liquid chromatography (LC) and capillary electrophoresis (CE). The types of hop samples, the optimized protocols to extract the hop acids, and the main instrumental conditions for both LC and CE techniques are highlighted and discussed. Specific and critical aspects of the - and β-acids separation by LC and CE and some challenges in this field are raised. Several key aspects discussed in this review may be of practical importance for brewers, whether in the microbrewery or industry and for researchers in the brewing field.
As aging progresses,
-amyloid (A
) deposition and the resulting oxidative damage are key causes of aging diseases such as senior osteoporosis (SOP).
L. (hops) is an important medicinal plant widely ...used in the food, beverage and pharmaceutical industries due to its strong antioxidant ability. In this study, APP/PS1 mutated transgenic mice and A
-injured osteoblasts were used to evaluate the protective effects of hops extracts (HLE) on SOP. Mice learning and memory levels were assessed by the Morris water maze. Mice femurs were prepared for bone micro-structures and immunohistochemistry experiments. The deposition of A
in the hippocampus, cortex and femurs were determined by Congo red staining. Moreover, protein expressions related to antioxidant pathways were evaluated by Western blotting. It was found that HLE markedly improved learning abilities and ameliorated memory impairment of APP/PS1 mice, as well as regulated antioxidant enzymes and bone metabolism proteins in mice serum. Micro-CT tests indicated that HLE enhanced BMD and improved micro-architectural parameters of mice femur. More importantly, it was discovered that HLE significantly reduced A
deposition both in the brain and femur. Further in vitro results showed HLE increased the bone mineralization nodule and reduced the ROS level of A
-injured osteoblasts. Additionally, HLE increased the expression of antioxidant related proteins Nrf2, HO-1, NQO1, FoxO1 and SOD-2. These results indicated that
L. extract could protect against senior osteoporosis through inhibiting A
deposition and oxidative stress, which provides a reference for the clinical application of hops in the prevention and treatment of SOP.
It is common knowledge that the composition of hops secondary metabolites depends on several factors, among which the storage conditions. In recent years, many studies have been conducted to evaluate ...changes in the chemical composition of hop products in response to different storage temperatures both in aerobic and anaerobic environments. However, little knowledge exists regarding the storage of hop pellets under modified atmosphere for a very long period of time. The aim of this study is to evaluate the effect on hop quality parameters of different storage conditions on U.S. hop cultivar pellets (Chinook and Nugget) in a three-year trial. Storage in modified atmosphere (atmosphere saturated with 70% nitrogen (N2) and 30% carbon dioxide (CO2) and vacuum storage were tested at two different temperatures, 4 °C and 10 °C. In order to establish the best storage condition, the bitter acids content (HPLC-UV method), the essential oil content (steam distillation method) and the essential oil profile (GC-MS method) were determined and characterised at 0, 6, 12 and 36 months. No statistical differences were observed between samples stored under different atmospheres, while significant differences were highlighted as a result of the storage temperature, e.g. the alpha acids content at 4 °C was significantly higher (P = 0.002). The two hop cultivars showed different behaviours in the storage trial, suggesting that high alpha hop varieties, like Nugget, could be stored even at higher temperatures.
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•Hops can be stored for a long time under anaerobic conditions.•During storage, a slight decrease in bitter acids is observed, regardless of storage temperature.•Aromatic profile of hops stored for a long time, at 4 and 10 °C, changes significantly.•Shelf life of hop pellets is cultivar dependent.•To preserve alpha and beta acids hops can be stored at 10 °C.
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•Enriched bitter acids extract from a Brazilian hop variety was successfully produced.•Drying temperature greatly affects hop color and total essential oil content.•Lupulin gland ...protected bitter acids and xanthohumol from oxidation during drying.•Drying up to 70 °C does not influence Supercritical CO2 extraction yields.
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.
The harvesting of hops (Humulus lupulus L.) generates large amounts of nutrient-rich leaves that can be used in composting mixtures to add value to other organic resources on the farm. In this study, ...hop leaves were mixed with cow manure and wheat straw in several combinations with the aim of establishing guidelines on how farmers can manage the raw materials and better use these valuable organic resources. The composting process was monitored and the quality of the composts evaluated in relation to the effects on lettuce (Lactuca sativa L.) grown in pots over two consecutive cycles. The mixture of hop leaves with cow manure produced a stable compost after nine months of composting which may be used in horticultural crops, irrespective of the proportion of raw materials, due to their low and similar C/N ratios. However, when using mixtures of leaves and straw in proportions of less than 2:1, the composts did not mature properly, showing high C/N ratios. Their application to the soil led to a strong reduction in plant tissue N concentrations, due to biological N immobilization, which significantly reduced lettuce dry matter yield. Thus, to reduce composting time and increase the quality of the compost, the ratio leaves/straw should be as high as possible, at least 2:1. Alternatively, either the composting process should take longer, or the poorly-matured compost be applied far in advance of sowing a crop so that complementary biological processes can take place in the soil, as recorded in the second cycle of lettuce. Ash from hop stems did not benefit the composting process and proved itself not to be worth using in mixtures.
•Hop leaves accelerated the decomposition rate and increased the quality of straw-based composts.•Hop leaves and farmyard manure produced stable composts irrespective of the proportion of raw materials.•Ash from hop stems did not add anything relevant to the composting process of hop leaves and other waste.•Poorly-matured compost should be applied far in advance of sowing a crop.
Hops are a major component of beer that is added during brewing. In addition to its wide range of bioactivity, it exhibits neuroactive properties as a sedative and sleeping aid. The compounds ...responsible for this activity are yet to be revealed and understood in terms of their pharmacological properties. Here we evaluated the potential of several hops flavonoids in modulating the GABAergic activity and assessed their selectivity to GABAA receptors subtypes. GABA-potentiating effects were measured using 3Hethynylbicycloorthobenzoate (EBOB) radioligand binding assay in native and recombinant α1β3γ2, α2β3γ2 and α6β3δ receptors expressed in HEK293 cells. Flumazenil sensitivity of GABA-potentiating effects and 3HRo 15-4513 binding assay were used to examine the flavonoids binding to benzodiazepine site. The prenylflavonoids xanthohumol (XN), isoxanthohumol (IXN) and 8-prenylnaringenin (8PN) potentiated GABA-induced displacement of 3HEBOB binding in a concentration-dependent manner. The IC50 for this potentiation in native GABAA receptors were 29.7 µM, 11.6 µM, 7.3 µM, respectively. In recombinant receptors, the sensitivity to prenylflavonoid potentiation of GABA-induced displacement of 3HEBOB binding followed the order α6β3δ > α2β3γ2 > α1β3γ2 with the strongest inhibition observed by 8PN in α6β3δ (IC50 = 3.6 μM). Flumazenil had no significant effect on the prenylflavonoid-induced displacement of 3HEBOB binding and 3HRo 15-4513 displacement from native GABAA receptors was only detected at high micromolar concentrations (100 µM). We identified potent prenylflavonoids in hops that positively modulate GABA-induced responses in native and αβγ/δ recombinant GABAA receptors at low micromolar concentrations. These GABAergic modulatory effects were not mediated via the high-affinity benzodiazepine binding site.
Hop powdery mildew, caused by Podosphaera macularis, may be initiated by sexual or asexual spores of the pathogen, but only asexual reproduction has been reported in the Pacific Northwest United ...States. In this region, overwintering is via bud perennation, leading to "flag shoots" the following season. We expanded on previous research and analyzed 766 location-years of flag shoot data from Oregon hop yards collected from 2014 to 2020, examining potential risk factors of yard age, cultivar susceptibility to powdery mildew, pruning method (mechanical means or not), and pruning thoroughness. Bayesian logistic regression models were fitted to estimate the probability of flag shoot presence or absence. We found little evidence to support yard age as a significant risk factor for flag shoot presence, as the 95% credible interval for the parameter associated with yard age was consistently centered around 0 in each of our models. However, cultivar susceptibility to powdery mildew, spring pruning method, and spring pruning thoroughness were associated with increases in the probability of observing a flag shoot. Although yard age was not an important risk factor, there was an interrelationship between yard age, pruning method, and pruning thoroughness that suggests second-year yards may indirectly be at an elevated risk for flag shoot development because these yards are less often pruned using mechanical methods. Our research further identifies yards that are most at risk for overwintering of P. macularis and reinforces the importance of thorough pruning in yards with an elevated risk for possessing a flag shoot.
Formula: see text The author(s) have dedicated the work to the public domain under the Creative Commons CC0 “No Rights Reserved” license by waiving all of his or her rights to the work worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law, 2023.
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