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PubMed2004

Xanthohumol and related prenylflavonoids from hops and beer: to your good health!

Xanthohumol (3'-[3,3-dimethyl allyl]-2',4',4-trihydroxy-6'-methoxychalcone) is the principal prenylated flavonoid of the female inflorescences of the hop plant ('hops'), an ingredient of beer. Human exposure to xanthohumol and related prenylflavonoids, such as 8-prenylnaringenin and isoxanthohumol, is primarily through beer consumption. Xanthohumol has been characterized a 'broad-spectrum' cancer chemopreventive agent in in vitro studies, while 8-prenylnaringenin enjoys fame as the most potent phytoestrogen known to date. These biological activities suggest that prenylflavonoids from hops have potential for application in cancer prevention programs and in prevention or treatment of (post-)menopausal 'hot flashes' and osteoporosis. Xanthohumol and 8-prenylnaringenin are metabolized into many flavonoid derivatives with modified 3,3-dimethyl allyl (prenyl) moieties. Xanthohumol is formed in lupulin glands by a specialized branch of flavonoid biosynthesis that involves prenylation and O-methylation of the polyketide intermediate chalconaringenin. Although a lupulin gland-specific chalcone synthase is known, the aromatic prenyltransferase and O-methyltransferase participating in xanthohumol have not been identified. The prenylflavonoid pathway is a possible target for breeding or biotechnological modification of hops with the aim of increasing xanthohumol levels for beer brewing and 8-prenylnaringenin levels for pharmaceutical production.

Anticarcinogenic Agents↗
PubMed2005

Price elasticity of demand for malt liquor beer: findings from a US pilot study.

Our objective is to estimate the relative price elasticity of demand for malt liquor beer (MLB), regular beer, hard liquor, and a combined group of all other alcoholic beverages. Three hundred and twenty-nine alcohol consumers (mostly male) in South-Central Los Angeles answered a series of questions pertaining to expected consumption responses to hypothetical price increases. We found that based on a 10% price increase, the mean price elasticity of demand (% change in quantity demanded / % change in price) was -0.79 for MLB drinkers, -1.14 for regular beer drinkers, -1.11 for hard liquor drinkers, and -1.69 for the combined group of all other drinkers. Logistic regression analysis revealed that the personal characteristics significantly related to being a MLB drinker were older age, not working, being homeless, and a daily drinker. Daily (or nearly daily) drinkers were more likely to be married, earning lower incomes, and hard liquor drinkers. This study is the first to investigate the price elasticity of demand for MLB drinkers and other heavy alcohol consumers in poor urban neighborhoods of the US. Future research can use the methods from this pilot study to more rigorously examine and compare the price sensitivity among heavy drinking groups.

Adult↗
PubMed1980

Use of cation-exchange resin for the detection of alkylpyridines in beer.

A method has been devised whereby trace amounts of certain basic compounds, such as pyridines, may be detected and semi-quantified in beer in the presence of an excess of other flavour constituents including pyrazines. The method involves steam distillation of beer under reduced pressure and subsequent passage of the distillate through a column of weakly acidic Zerolit cation-exchange resin. The resin is eluted with aqueous sodium chloride, the eluate extracted with organic solvent and the concentrated extract analysed by gas chromatography coupled with mass spectrometry. Using this technique with multiple ion detection, a series of alkylpyridines was readily detectable in beers and worts at levels below 1 ppb.

Beer↗
PubMed2000

In vitro approach to evaluate potential harmful effects of beer on teeth.

OBJECTIVE: The purpose of the present work was to examine some properties of different brands of beer manufactured in Brazil that may be important to oral health. METHODS: Samples from seven different beer brands were analyzed for pH, titratable acidity, calcium and phosphate concentrations. Demineralization experiments were carried out by incubating samples with crown tooth particles (40-80 mesh) at 37 degrees C under agitation (100 strokes/min). RESULTS: The pH was lower than 4.0 for three of the seven samples and higher than 4.0 for the others. The amount of titratable acidity, expressed as the volume of 0.1N NaOH solution consumed to raise the initial pH to 7.0, and the concentrations of calcium and phosphate varied. Calcium concentration ranged from 0.21 to 1.59 micromol/ml, while phosphate concentration varied from 0.048 to 0.094 micromol/ml. Calcium released to the incubation medium was proportional to the time of incubation up to 5min. Maltose, a disaccharide, was detected in all samples studied. CONCLUSION: Differences in the properties examined indicated that some brands of beer studied may have potential dental effects.

Beer↗
PubMed1999

Glycine betaine in beer as an antimutagenic substance against 2-chloro-4-methylthiobutanoic acid, the sanma-fish mutagen.

Beer can inhibit the mutagenicity of the sanma-fish mutagen, 2-chloro-4-methylthiobutanoic acid (CMBA) in Salmonella typhimurium TA100 and TA1535. The antimutagenic component was isolated from beer and identified as glycine betaine, a compound known to be distributed widely in plants and animals including humans. Beer also contains components that interfere the antimutagenic action of glycine betaine. Glycine betaine seems to antagonize CMBA in a specific manner, since several other direct-acting mutagens tested were not subject to inhibition by glycine betaine. CMBA was stable in the presence of glycine betaine under neutral conditions. Since a treatment of Salmonella with glycine betaine before the bacteria was exposed to CMBA resulted in inhibition of the mutagenesis, the antimutagenic action of glycine betaine may be taking place inside the cells. These observations suggest that the mutagenic action of CMBA may be modified by the presence of both extracellular and intracellular glycine betaine.

Animals↗
PubMed2003

Molecular genetic identification of Saccharomyces sensu stricto strains from African sorghum beer.

Genetic relationships of 24 phenotypically different strains isolated from sorghum beer in West Africa and the type cultures of the Saccharomyces sensu stricto species were investigated by universally primed polymerase chain reaction (PCR) analysis, microsatellite fingerprinting and PCR-restriction fragment length polymorphism (RFLP) of the ribosomal internal transcribed spacers. The results demonstrate that internal transcribed spacer (ITS) PCR-RFLP analysis with the endonucleases HaeIII, HpaII, ScrFI and TaqI is useful for discriminating S. cerevisiae, S. kudriavzevii, S. mikatae from one another and from the S. bayanus/S. pastorianus and S. cariocanus/S. paradoxus pairs. The sorghum beer strains exhibited the same restriction patterns as the type culture of S. cerevisiae CBS 1171. PCR profiles generated with the microsatellite primer (GTG)(5) and the universal primer N21 were almost identical for all isolates and strain CBS 1171. Despite phenotypic peculiarities, the strains involved in sorghum beer production in Ghana and Burkina Faso belong to S. cerevisiae. However, based on sequencing of the rDNA ITS1 region and Southern hybridisation analysis, these strains represent a divergent population of S. cerevisiae.

Base Sequence↗
PubMed2004

Quantification of organic and amino acids in beer by 1H NMR spectroscopy.

The quantification of organic and amino acids in beer using 1H NMR spectroscopy is demonstrated. Quantification was made both by integration of signals in the spectra together with use of calibration references and by use of partial least-squares (PLS) regression. Results from the NMR quantifications were compared with those obtained from determinations by amino acid analysis on HPLC and organic acid analysis by capillary electrophoresis. The described NMR-based methods could satisfactorily be used for quantification of several of the investigated metabolites in beer down to approximately 10 mg/L and for most with a good to high accuracy compared to results obtained by HPLC and capillary electrophoresis (R2 0.90-0.99). This was achieved with a simple sample preparation and one-dimensional 1H NMR spectra obtained in a few minutes. The use of PLS clearly improves the accuracy of the quantifications, based on comparison to results obtained by HPLC and capillary electrophoresis, and furthermore permits the determination of components with partially overlapped signals in the spectrum. NMR spectroscopy in combination with PLS will be a useful tool for the quantification of metabolites, not only in beer but also in other beverages and biofluids.

Amino Acids↗
PubMedDate not supplied

Improved performances and control of beer fermentation using encapsulated alpha-acetolactate decarboxylase and modeling.

The use of the enzyme alpha-acetolactate decarboxylase allows the acceleration of beer fermentation/maturation because it shunts diacetyl formation, whose elimination is the rate-limiting step of the process. To obtain a cost reduction by using this exogenous enzyme, we propose a new process involving recoverable encapsulated alpha-acetolactate decarboxylase. The performance of traditional and new processes was investigated by a modeling approach. A simple model, focused on alpha-acetolactate and diacetyl profiles during beer fermentation, was set up. The simulated profiles are consistent with literature data. This study shows also that encapsulated alpha-acetolactate decarboxylase allows the acceleration of beer fermentation as efficiently as free alpha-acetolactate decarboxylase. The advantage of immobilized alpha-acetolactate decarboxylase versus free enzyme is that it is recoverable and reusable, which means a process cost reduction.

Acetoin Dehydrogenase↗
PubMed2001

Assay of ochratoxin A in wine and beer by high-pressure liquid chromatography photodiode array and gas chromatography mass selective detection.

To routinely assay the concentrations of ochratoxin A (OTA) in wines and beers, two new methods were developed and evaluated. The first utilized solid-phase extraction on a C(18) cartridge to achieve a 100-fold sample concentration followed by high-performance liquid chromatography on a C(18) column with gradient elution and quantitation at 333 nm by means of a photodiode array detector. Positive confirmation can be carried out by purity and match-factor analysis as well as peak shift following esterification with BF(3). Total run time is 28 min. The limits of detection (LOD) and quantitation (LOQ) are 0.05 and 0.10 microg/L, respectively. Recovery and imprecision ranged from 83 to 94% and from 4.0 to 8.9%, respectively. With a throughput of 35 assays per working day, this method is ideal for routine OTA analysis. It was used to survey the concentrations of OTA in 942 wines (2 of which gave values between 0.1 and 0.2 microg/L) and 107 beers (2 of which gave values between 0.05 and 0.1 microg/L). OTA was detected more frequently in red than white wines, with the highest incidence in red wines from Spain and Argentina. There was no association between OTA and country of origin or beverage type among the beers analyzed. The second method utilized gas chromatography with mass selective detection monitoring eight specific ions, preceded by extraction in dichloromethane and derivatization with bis[trimethylsilyl]trifluoroacetamide. LOD and LOQ were 0.1 and 2 microg/L, respectively; recovery and imprecision were 69-75 and 9.0-11.1%, respectively. The method is not suitable for routine quantitation but is potentially useful as a confirmatory tool for samples with OTA > or =0.1 microg/L.

Beer↗
PubMed2002

High-resolution nuclear magnetic resonance spectroscopy and multivariate analysis for the characterization of beer.

Beer contains a very complex mixture of nutrients, which in this work are identified to some extent by high-field high-resolution nuclear magnetic resonance (NMR) one- and two-dimensional methods. The (1)H NMR spectrum of beer shows a predominance of strongly overlapped peaks arising from several carbohydrates. Minor components are clearly observed both in the aliphatic and in the aromatic regions of the spectrum. With the aid of two-dimensional methods, spectral assignment was carried out, enabling the identification of approximately 30 compounds and identifying about the same number of spin systems for further assignment. The variability of the spectral profile of beers differing in type and label was studied by principal component analysis (PCA), and it was found that, although some distinction is achieved on the basis of the aliphatic and sugar compositions, clearer separation between ales and lagers is obtained by PCA of the aromatic profiles alone. The potential of this technique as a rapid and informative quality control tool is discussed.

Analysis of Variance↗
PubMed2002

Release of deuterated (E)-2-nonenal during beer aging from labeled precursors synthesized before boiling.

Although lipid autoxidation in the boiling kettle is a key determinant of the cardboard flavor of aged beers, recent results show that mashing is another significant source of wort nonenal potential, the well-known indicator of how a beer will release (E)-2-nonenal during storage. Although unstable, deuterated (E)-2-nonenal nitrogen adducts created during mashing can in some cases partially persist in the pitching wort, to release deuterated (E)-2-nonenal during beer aging. In the experiment described here, the relative contributions of mashing and boiling were estimated at 30 and 70%, respectively. The presence of oxygen during mashing and, to a lesser extent, high lipoxygenase activity can intensify the stale cardboard flavor.

Aldehydes↗
PubMed2003

Analysis of aldehydes in beer using solid-phase microextraction with on-fiber derivatization and gas chromatography/mass spectrometry.

A new, fast, sensitive, and solventless extraction technique was developed in order to analyze beer carbonyl compounds. The method was based on solid-phase microextraction with on-fiber derivatization. A derivatization agent, O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine (PFBOA), was absorbed onto a divinyl benzene/poly(dimethylsiloxane) 65-microm fiber and exposed to the headspace of a vial with a beer sample. Carbonyl compounds selectively reacted with PFBOA, and the oximes formed were desorbed into a gas chromatograph injection port and quantified by mass spectrometry. This method provided very high reproducibility and linearity. When it was used for the analysis of aged beers, nine aldehydes were detected: 2-methylpropanal, 2-methylbutanal, 3-methylbutanal, pentanal, hexanal, furfural, methional, phenylacetaldehyde, and (E)-2-nonenal.

Aldehydes↗
PubMed2005

Automated on-line solid-phase extraction-liquid chromatography-electrospray tandem mass spectrometry method for the determination of ochratoxin A in wine and beer.

An automated on-line solid-phase extraction-liquid chromatography-electrospray tandem mass spectrometry (SPE-LC-ESI-MS/MS) method was developed for the determination of ochratoxin A (OTA) in alcoholic beverages. Mean recoveries for wine and beer were, respectively, 75 and 82%. Detection was achieved in negative ionization with a Q TRAP mass spectrometer operating in multiple-reaction monitoring (MRM) mode or enhanced product ion (EPI) mode, using the third quadrupole as linear ion trap. The MRM mode turned out to be more sensitive; the method allowed accurate determination of OTA in the range of 0.01-25 ng mL(-1) using external calibration. Within-day and between-day relative standard deviation percentages were <6.2 and <9.1%, respectively. In EPI mode, fragmentation spectra at the limit of quantification (0.03 ng mL(-1)) and good linearity could be obtained. Application of the method (MRM mode) to the analysis of several wine and beer samples purchased in local stores revealed OTA levels in the ranges of 0.03-1.44 ng mL(-1) for wines and 0.02-0.14 ng mL(-1) for beers.

Autoanalysis↗
PubMed2005

Behavior of myclobutanil, propiconazole, and nuarimol residues during lager beer brewing.

Over a 4 month brewing process, the fate of three fungicides, myclobutanil, propiconazole, and nuarimol, was studied in the spent grain, brewer wort, and final beer product. Only the residual level of myclobutanil after the mashing step was higher than its maximum residue limit (MRL) on barley. A substantial fraction was removed with the spent grain in all cases (26-42%). The half-life times obtained for the fungicides during storage of the spent grains ranged from 82 to 187 days. No significant influence of the boiling stage on the decrease of the fungicide residues was demonstrated. During fermentation, the content reduction varied from 20 to 47%. After the lagering and filtration steps, no significant decrease (<10%) was observed in any of the residues. Finally, during storage of the beer (3 months), the amounts of fungicides fell by 25-50% of their respective concentrations in the finished beer.

Beer↗
PubMed2006

Determination and levels of the biocide ortho-phenylphenol in canned beers from different countries.

A method was developed for the determination of the biocide ortho-phenylphenol (biphenyl-2-ol; OPP) in beer, using deuterated OPP as an internal standard. A new liquid-liquid extraction procedure, employing acetonitrile, diethyl ether, and n-pentane, afforded rapid phase separation. The evaporated extract was derivatized with pentafluorobenzyl bromide in a water-acetonitrile mixture that was buffered with potassium carbonate, followed by extraction of the derivative into cyclohexane and analysis by gas chromatography-mass spectrometry in electron ionization mode. The method enables the detection of OPP in 50 mL of beer at concentrations as low as 0.1 microg/L and provides a linear range of quantification of 0.5-40 microg/L. Samples from 61 beers canned over the past 12 years and sold in 27 countries were analyzed for OPP. In 40 of them, the target compound was present at concentrations of 1.2-40 microg/L. Our investigations indicate that the ends of the cans, which contain sealing material presumably treated with OPP, are responsible for this contamination.

Agrochemicals↗
PubMed2006

Phenol and terpene quenching of singlet- and triplet-excited states of riboflavin in relation to light-struck flavor formation in beer.

Phenolic compounds present in beer were shown by fluorescence spectroscopy and laser flash photolysis to deactivate both singlet- and triplet-excited states of riboflavin with bimolecular rate constants close to the diffusion control ranging from 2.8x10(9) to 1.1x10(10) M-1 s-1 and from 1.1x10(9) to 2.6x10(9) M-1 s-1, respectively. Enthalpies of activation were low (up to 33.2 kJ mol-1), and entropies of activation were positive, ranging from 17 to 92 J mol-1 K-1, as derived from temperature dependence, indicating a compensation effect. From a Stern-Volmer analysis of the singlet-excited riboflavin quenching by phenols it was found that high amounts of phenolic compounds (>0.3 M) would be needed to hinder triplet-excited riboflavin generation. On the other hand, a phenolic content of 0.36 mM is likely to quench 90% of the triplet-excited state. Phenol photodegradation was found to be complex, and using ESI-MS analysis it was not possible to identify specific photooxidation products of the phenolic compounds; only the photoproducts of riboflavin could be detected and structurally assigned. The rate of reaction of triplet-excited riboflavin with phenolic compounds in acetonitrile/citrate buffer (pH 4.6, 10 mM) is 550 times faster than the reaction with iso-alpha-acids from hops, indicating that triplet-excited quenchers such as phenols may be involved in the early steps in light-struck flavor formation in beer through radical formation. Terpenes present in herb-flavored beers were found to be nonreactive toward singlet- and triplet-excited-state riboflavin, and any protection depends on other mechanisms.

Beer↗
PubMed1977

Colorectal cancer and beer drinking.

Evidence is presented of a significant statistical association between beer drinking and colorectal cancer, particularly rectal cancer. This finding is based on correlations between consumption and cancer mortality and between changes in consumption and changes in cancer mortality for 47 states in the United States of America. Also various secular trends, an urban-rural gradient, socioeconomic gradients and sex ratios in the United States are shown to be generally consistent with a relationship between beer consumption and colorectal cancer, particularly rectal cancer. The limitations on drawing sound aetiological inferences from such data are acknowledged. In particular, several other variables are shown to be associated with both beer drinking and colorectal cancer. Also, a discussion of previous epidemiological studies is given, and it appears there is only a limited amount of direct evidence in humans to support the statistical demographic relationships.

Alcohol Drinking↗
PubMed1989

Spectrophotometric determination of tannins in tea and beer samples with iron(III) and 1,10-phenanthroline as reagents.

A simple and accurate spectrophotometric method is proposed for the determination of tannins in tea and beer samples based on the reduction of iron(III) to iron(II) by tannins at 80 degrees C for 20 min. The iron(II) was then reacted with 1,10-phenanthroline at pH 4.4 to form a coloured complex. Background correction could be effected by precipitating the tannins in the sample solution twice with gelatin and kaolin. Absorbance measurements were made at 540 nm and the calibration graph was linear from 0 to 5.5 micrograms ml-1 of tannic acid with a slope of 0.213 A p.p.m.-1. The precision for the determination of tannins in a tea sample containing 9.45% of tannins was 1.8%. Most of the ingredients commonly found in tea and beer samples do not interfere with the determination. Several tea and beer samples were analysed for their tannin content using the proposed method.

Beer↗