Although female cones of the hop plant (Humulus lupulus) are known primarily as raw material supplying characteristic bitterness and aroma to beer, their equally significant health-promoting effects have been known to mankind for several thousand years and hop is a plant traditionally utilized in folk medicine. This paper summarizes the scientific knowledge on the effects of all 3 major groups of secondary metabolites of hops; polyphenols, essential oils, and resins. Because of their chemical diversity, it is no coincidence that these compounds exhibit a wide range of pharmacologically important properties. In addition to antioxidant, anti-inflammatory, and anticancer-related properties, particular attention is being paid to prenylflavonoids that occur almost exclusively in hops and are considered to be some of the most active phytoestrogens known. Hop oils and resins are well known for their sedative and other neuropharmacological properties, but in addition, these compounds exhibit antibacterial and antifungal effects. Recently, alpha bitter acids have been shown to block the development of a number of complex lifestyle diseases that are referred to by the collective name "metabolic syndrome." Information presented in this review confirms the significant potential for the use of hops in the pharmaceutical industry and provides an understanding of beer as a natural drink that, although moderately consumed, may become a source of many health-promoting compounds.

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Historically, hop cones (Humulus lupulus) have been used since ancient times as a remedy for many ailments and, as a source of polyphenols and bitter acids, is very effective in the treatment of metabolic syndrome (MS). Hop flavonoids, particularly xanthohumol (XN), are substances with hypoglycemic, antihyperlipidemic, and antiobesity activities. Iso-α-acids (IAA) and matured hop bitter acids (MHBA) improve health by influencing lipid metabolism, glucose tolerance, and body weight. The modulatory effect of IAA and MHBA on lipid metabolism may also be responsible for a loss in body weight. These results suggest promising applications for IAA, MHBA, and XN in humans, particularly in the prevention of diet-induced obesity and diabetes.

Arrested or limited fermentation process is a widespread method used for production of alcohol-free beer (AFB). However, it usually leads to worty off-flavour and a lack of pleasant fruity flavour/aroma. The aim of this study was to isolate spontaneous mutants of Saccharomyces pastorianus strain 2 resistant to 5,5,5-trifluoro-DL-leucine, since the resistance is related to overproduction of flavour active isoamyl alcohol (IAAL) and isoamyl acetate (IAAC). The mutants were the subject of selection during series of screening tests aimed at selecting the best producer of target compounds (IAAL and IAAC). Subsequently, the overproduction stability of the selected mutant strain was verified in four consecutive fermentations of AFBs. A higher pitching rate and increased fermentation temperature did not result in an overall improvement in the production of the target compounds. Sensory analysis proved the flavouring effect of the spontaneous lager yeast mutant on the AFB produced by arrested fermentation.

Hop (Humulus lupulus L.), as a key ingredient for beer brewing, is also a source of many biologically active molecules. A notable compound, 8-prenylnaringenin (8-PN), structurally belonging to the group of prenylated flavonoids, was shown to be a potent phytoestrogen, and thus, became the topic of active research. Here, we overview the pharmacological properties of 8-PN and its therapeutic opportunities. Due to its estrogenic effects, administration of 8-PN represents a novel therapeutic approach to the treatment of menopausal and post-menopausal symptoms that occur as a consequence of a progressive decline in hormone levels in women. Application of 8-PN in the treatment of menopause has been clinically examined with promising results. Other activities that have already been assessed include the potential to prevent bone-resorption or inhibition of tumor growth. On the other hand, the use of phytoestrogens is frequently questioned regarding possible adverse effects associated with long-term consumption. In conclusion, we emphasize the implications of using 8-PN in future treatments of menopausal and post-menopausal symptoms, including the need for precise evidence and further investigations to define the safety risks related to its therapeutic use.

The determination of polyphenols by spectrophotometric detection is complicated due to their low concentrations in beer. The beer samples have to be pre-concentrated before using the spectrophotometric detection for their quantification. An analytical method based on solid-phase extraction (SPE) and followed by high performance liquid chromatographic separation with diode-array detection is used for the determination of free gallic, protocatechuic, caffeic, p-coumaric, ferulic and salicylic acids, of (+)-catechin, (–)-epicatechin, and quercetin. These phenolic compounds participate in colloidal and sensory stability of beer. Six different SPE cartridges were tested and three different types of elution with the most appropriate solvents (acetonitrile, acetone and methanol) were used. The performance of the HPLC method was assessed by the evaluation of parameters such as absolute recovery, relative standard deviation (RSD – lower than 10%), the limit of quantification (LOQ), and the limit of detection (LOD). The polyphenol content in various types of Czech beer is presented.

Jelínek L., Šneberger M., Karabín M., Dostálek P. (2010) Seven Czech hop varieties (dry hop cones) coming from the harvest of 2008 (Agnus, Bor, Harmonie, Premiant, Rubín, Sládek, and Saaz) were compared for their composition depending on their varietal differentiation. These cultivars were analysed for the contents of α-and β-bitter acids analogues, essential oils, and polyphenols. Hop essential oil constituents significantly contribute to the individual hop varieties. The dichotomous key for the authentication of Czech hop varieties was established based on some characteristic varietal markers.

Xanthohumol is a hop polyphenol with proven positive effects on human health. The aim of this work was to use special malts (roasted malt and melanoidin malt) for the preparation of high-gravity sweet worts with an extremely high xanthohumol content. The solubility of xanthohumol was higher in sweet worts prepared from roasted malts than from Pilsen or melanoidin malts. This sweet wort (xanthohumol~20 mg L À1 ) was used for the preparation of xanthohumol-rich beer. The importance of melanoidins in xanthohumol solubility was also examined. Isomerization reactions occurring at increased temperatures is one of the main reasons for the loss of xanthohumol in the brewing process and therefore the most appropriate temperature for addition of xanthohumol products to sweet worts was determined. The influence of filtration and stabilization materials (diatomaceous earth, polyamide sorbents and tannic acid) on the concentration of xanthohumol in enriched beer was also examined. Only a small effect of these materials was shown in xanthohumol-rich dark beers, with the exception of tannic acid, which removed a significant amount of this polyphenol.