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At least 127 records · Page 7Linked to original sources
PubMed2002

Role of beer lipid-binding proteins in preventing lipid destabilization of foam.

The negative effect of fatty acids on the foam stability of beer has been assessed. Long-chain fatty acids are far more damaging than short-chain fatty acids on the foam stability of beer at the concentrations employed. Polypeptides have been isolated from an all malt beer by hydrophobic interaction chromatography. Using this technique five groups of polypeptides were isolated, group 1 being the least hydrophobic and group 5 the most hydrophobic, all of which exhibited similar polypeptide compositions by SDS-PAGE. All five hydrophobic polypeptide groups bound [(14)C]linoleic acid; however, group 5, the most hydrophobic group, bound the most linoleic acid. Groups 1 and 5 were titrated with cis-parinaric acid (CPA) to produce binding curves, which were compared with a binding curve obtained for bovine serum albumin (BSA). Groups 1 and 5 both produced binding curves that saturated at approximately 5.5 microM and 4 microM CPA and had association constants (K(a)) of 6.27 x 10(7) and 1.62 x 10(7) M(-1), respectively. In comparison, BSA produced a binding curve that saturated at 6 microM CPA and had a K(a) of 3.95 x 10(7) M(-1). Further investigation has shown that group 1 is pH sensitive and group 5 pH insensitive with respect to lipid binding. The lipid-binding activity of group 5 was also shown to be unaffected by ethanol concentration. Linoleic acid (5 microM) when added to beer resulted in unstable foam. Group 5 was added to the lipid-damaged beer and was shown to restore the foam stability to values that were obtained for the control beer. It has therefore been demonstrated that proteins isolated from beer have a lipid-binding capacity and that they can convey a degree of protection against lipid-induced foam destabilization.

Beer↗
PubMed2002

How low pH can intensify beta-damascenone and dimethyl trisulfide production through beer aging.

Flavor quality is of major importance to the consumer, but the flavor characteristics of beer appear to deteriorate greatly with time, at a rate depending on the composition of the beer and its storage conditions (notably pH). Prior to identifying the influence of pH on the development of the most intense staling flavors found in aged lager beers, the corresponding key flavor compounds were determined by aroma extract dilution analysis. In addition to trans-2-nonenal, beta-damascenone seems at least as important in the flavor of aged beer. Ethyl butyrate, dimethyl trisulfide, 2-acetylpyrazine, 3-(methylthio)propionaldehyde, 2-methoxypyrazine, maltol, gamma-nonalactone, and ethyl cinnamate are also relevant to the sensory profile of aged beer. Upon aging, a beer having a higher pH produces less beta-damascenone, because acid-catalyzed glycoside hydrolysis is decreased. On the other hand, it produces more 3-(methylthio)propionaldehyde, owing to Strecker degradation of methionine. Raising the beer pH additionally causes the release of 3-(methylthio)propionaldehyde from sulfitic adducts. These adducts, more stable at a lower pH, protect the aldehyde against premature oxidation to 3-(methylthio)propionic acid, thus making it available for dimethyl trisulfide formation during aging.

Beer↗
PubMed2004

Impact of different wort boiling temperatures on the beer foam stabilizing properties of lipid transfer protein 1.

Beer consumers demand satisfactory and consistent foam stability; thus, it is a high priority for brewers. Beer foam is stabilized by the interaction between certain beer proteins, including lipid transfer protein 1 (LTP1), and isomerized hop alpha-acids, but destabilized by lipids. In this study it was shown that the wort boiling temperature during the brewing process was critical in determining the final beer LTP1 content and conformation. LTP1 levels during brewing were measured by an LTP1 ELISA, using antinative barley LTP1 polyclonal antibodies. It was observed that the higher wort boiling temperatures ( approximately 102 degrees C), resulting from low altitude at sea level, reduced the final beer LTP1 level to 2-3 microg/mL, whereas the lower wort boiling temperatures ( approximately 96 degrees C), resulting from higher altitudes (1800 m), produced LTP1 levels between 17 and 35 microg/mL. Low levels of LTP1 in combination with elevated levels of free fatty acids (FFA) resulted in poor foam stability, whereas beer produced with low levels of LTP1 and FFA had satisfactory foam stability. Previous studies indicated the need for LTP1 denaturing to improve its foam stabilizing properties. However, the results presented here show that LTP1 denaturation reduces its ability to act as a binding protein for foam-damaging FFA. These investigations suggest that wort boiling temperature is an important factor in determining the level and conformation of LTP1, thereby favoring satisfactory beer foam stability.

Altitude↗
PubMed2004

Influence of the brewing process on furfuryl ethyl ether formation during beer aging.

In beer, the development of a solvent-like stale flavor is associated with the formation of furfuryl ethyl ether. The synthesis rate of this important flavor compound is proportional to the concentration of furfuryl alcohol in beer. This study shows that furfuryl alcohol in beer is mainly formed by Maillard reactions initiated during wort boiling and malt production. A mechanism for its formation from alpha-(1,4)-oligoglucans and amino acids in wort and beer is proposed. During wort boiling, a quadratic relationship was found between the wort extract concentration, on the one hand, and the increase of furfuryl alcohol and furfural, on the other. The reduction of furfural by yeast during fermentation further increases the furfuryl alcohol content. In pale beers, the furfuryl alcohol concentration is essentially determined by the thermal load on wort during brewing operations. In dark beers, a considerable fraction of furfuryl alcohol may, however, come from the dark malts used. These results lead to important practical conclusions concerning the control over furfuryl ethyl ether in beer.

Beer↗
PubMed2005

Effective prevention of chill-haze in beer using an acid proline-specific endoprotease from Aspergillus niger.

Chill-haze formation during beer production is known to involve polyphenols that interact with proline-rich proteins. We hypothesized that incubating beer wort with a proline-specific protease would extensively hydrolyze these proline-rich proteins, yielding a peptide fraction that is unable to form a haze. Predigestion of the proline-rich wheat gliadin with different proteases pointed toward a strong haze-suppressing effect by a proline-specific enzyme. This finding was confirmed in small-scale brewing experiments using a recently identified proline-specific protease with an acidic pH optimum. Subsequent pilot plant trials demonstrated that, upon its addition during the fermentation phase of beer brewing, even low levels of this acidic enzyme effectively prevented chill-haze formation in bottled beer. Results of beer foam stability measurements indicated that the enzyme treatment leaves the beer foam almost unaffected. In combination with the enzyme's cost-effectiveness and regulatory status, these preliminary test results seem to favor further industrial development of this enzymatic beer stabilization method.

Aspergillus niger↗
PubMed1999

Inhibitory effects of beer and other alcoholic beverages on mutagenesis and DNA adduct formation induced by several carcinogens.

The possibility that beer and other alcoholic beverages could be antimutagenic against the heterocyclic amines (HAs), a group of carcinogens produced on cooking proteinaceous foods, has been explored. In the Salmonella mutation assays, beer showed inhibitory effects against several HAs [preactivated Trp-P-1, Trp-P-2(NHOH), and Glu-P-1(NHOH)] that are directly mutagenic in bacteria. Japanese sake, red and white wines, and brandy were also effective. However, ethyl alcohol alone did not show these effects. The formation of O(6)-methylguanine by N-methyl-N'-nitro-N-nitrosoguanidine in the DNA of Salmonella YG7108 was also inhibited by beer. Nonvolatile beer components were administered orally to CDF(1) mice together with Trp-P-2. Adducts in the liver DNA were significantly decreased by the beer, as compared to those in controls fed Trp-P-2 only. Although several phenolic compounds known to be present in beer were antimutagenic toward these mutagens, their effects were very small. It was concluded that some yet to be identified component(s) of beer is (are) responsible for this antimutagenicity.

Alcoholic Beverages↗
PubMed2005

Effects of long-term beer ingestion on plasma concentrations and urinary excretion of purine bases.

To investigate the long-term effects of beer ingestion on plasma concentrations of purine bases (hypoxanthine, xanthine, and uric acid), ten healthy males ingested beer (15 ml/kg body weight) every evening for three months. Blood and 24-hour urine samples were collected in the morning on one day before and one, two, and three months after starting the experiment to determine the plasma concentrations and urinary excretion of uric acid, hypoxanthine, and xanthine. Plasma concentrations and urinary excretion of uric acid, hypoxanthine, and xanthine in five of the participants that did not regularly ingest beer at a quantity of more than 15 ml/kg body weight in a single day prior to the experiment were not increased during the experimental period. In contrast, plasma concentrations and urinary excretion of uric acid were increased in five participants who regularly ingested more than 15 ml/kg body weight of beer in a single day prior to the experiment, although hypoxanthine and xanthine levels were not significantly increased during the experimental period. In both groups, uric acid clearance and purine ingestion were not significantly different throughout the study. Our results suggest that the production of uric acid caused by ethanol ingestion from beer is a significant contributor to the increase in plasma uric acid concentration in patients that regularly consume more than 15 ml/kg body weight of beer each day. Therefore, patients with gout should be encouraged to refrain from drinking large amounts of beer on a daily basis.

Adult↗
PubMed1988

Attempts to train novices for beer flavor discrimination: a matter of taste.

Inexperienced beer-drinkers who could not pass a beer-flavor discrimination test were divided into a taste group, which received additional perceptual experience with beer flavors; a verbal group, which received instruction in beer flavor terminology; a taste/verbal group, which received both additional experience and instruction; and a control group. Before and after training, all subjects participated in a similarity rating task involving beer flavors and flavor-related adjectives. Additional taste experience--but not increased experience with beer-flavor terminology--improved novices' ability to detect identical beer flavors. Results are discussed in terms of the trainability of flavor discrimination and the role of cognitive factors (both flavor-related and flavor-independent) in marketing beverages.

Beer↗
PubMed2002

Mycotoxins in South African traditionally brewed beers.

Traditionally brewed alcoholic beverages are regularly consumed by most ethnic black South Africans. Maize and barley, both of which are used for producing locally brewed alcoholic beer, are frequently contaminated by mycotoxin-producing moulds. The study was undertaken to investigate whether these toxins are present in raw grains and the traditional beers imbibed by the local black African population. It was established that the raw ingredients (sorghum, sorghum malt grains, maize grits), commercially produced traditional beers (Utshwala and Utshwala special) and home-brewed beers (Umqombotha, Isiqatha, Imfulamfula) were contaminated by bacteria and fungi (both yeasts and moulds). The contaminating moulds were isolated and identified. The contaminated samples were analysed for aflatoxins B1, B2, G1 and G2, zearalenone, citrinin, deoxynivalenol, and ochratoxin A using a multi-mycotoxin thin-layer chromatography screening method and the toxins were quantified by high-performance liquid chromatography. Grain samples were infected by. Aspergillus flavus, A. alliaceus, A. clavatus, Penicillium spp., Rhizopus spp. and Mucor spp. Sorghum malt grain samples contained the toxin zear alenone. No mycotoxin-producing fungi were present in the fermented beers but two of six commercial beer samples contained aflatoxins (200 and 400 microg l(-1) and 45% (13 of 29) of the home-brewed beers had zear alenone (range 2.6-426 microg l(-1) and/or ochratoxin A (3-2340 microg l(-1).

Bacteria↗
PubMed1997

Natural occurrence of trichothecenes and zearalenone in Korean and imported beers.

In order to survey the natural occurrence of Fusarium mycotoxins including deoxynivalenol (DON), nivalenol (NIV), and zearalenone (ZEN) in beers consumed in Korea, a total of 54 extracts of Korean and imported beers were derivatized with heptafluorobutyric anhydride and analysed by gas chromatography-mass spectrometry with selected ion monitoring mode. DON was detected in 14 samples (26%) and NIV was detected in 43 samples (80%). ZEN was not detected in any of the samples tested. The incidence of DON was 19% for Korean beers and 50% for imported beers, whereas the incidence of NIV was 85% for Korean beers and 58% for imported beers. This is the first report that the beers consumed in Korea are contaminated with DON and NIV.

Beer↗
PubMed1999

Presence and distribution of arsenical species in beers.

The total content of arsenic and of its inorganic (As(III) and As(V)) and organic (monomethylarsonic acid, MMAA, and dimethylarsinic acid, DMAA) species were determined in a set of 21 alcoholic and alcohol-free beer samples using the technique of Hydride Generation Atomic Absorption Spectrometry. For total arsenic analysis, beer samples were dried and then microwave digested with nitric acid in polytetrafluoroethylene containers. For the speciation analysis, beers were previously subjected to ion exchange chromatography to elute the mentioned inorganic and organic arsenical species. Both microwave digestion and chromatographic separation methods were validated from certified reference materials and prepared standard solutions, respectively. The results obtained are presented in terms of the distribution and occurrence of arsenical species in the samples. The As levels of the beer samples were in the range of 1.5-12.4 micrograms/l. The influence of the production process for the alcohol-free beers in the speciation of arsenic is discussed. In alcoholic beers MMAA was the most abundant species, and for non-alcoholic beers inorganic As(III) was similar to the organic species. An estimated intake of total As of 0.47 microgram/person/day and 11.4 micrograms/person/day was obtained for average consumers and for heavy drinkers, respectively.

Alcohol Drinking↗
PubMed2004

Genetic marker for differentiating beer-spoilage ability of Lactobacillus paracollinoides strains.

AIMS: To determine whether the beer-spoilage ability is an intrinsic character of Lactobacillus paracollinoides and identify a genetic marker for differentiating the beer-spoilage ability of strains belonging to this species. METHODS AND RESULTS: The ribotype of a nonspoilage strain, Lact. brevis ATCC8291, was found to be identical with that of Lact. paracollinoides LA7. The 16S rDNA sequence analysis and DNA-DNA hybridization study indicates that nonspoilage ATCC8291 should belong to Lact. paracollinoides. We further isolated nonspoilage variants from Lact. paracollinoides LA2(T) and LA9 by incubating these strains at 30 degrees C. To identify a genetic marker for differentiating the beer-spoilage ability of Lact. paracollinoides, open reading frames 5 (ORF5), the previously reported genetic marker for Lact. brevis, was evaluated. As a result, ORF5 homologues were detected in all of the 12 beer-spoilage strains of Lact. paracollinoides, while this ORF was not found in ATCC8291 or the two nonspoilage variants obtained from LA2(T) and LA9. CONCLUSIONS: Lactobacillus paracollinoides is not an intrinsic beer-spoiler and the nonspoilage strain Lact. brevis ATCC8291 should be reclassified as Lact. paracollinoides. ORF5 was found to be useful for differentiating beer-spoilage ability of this species. SIGNIFICANCE AND IMPACT OF THE STUDY: The finding that Lact. paracollinoides includes nonspoilage strains necessitates brewers to use a genetic marker that is associated with the beer-spoilage ability of this species.

Bacterial Proteins↗
PubMed1998

Correlation between the drinkability of beer and gastric emptying.

A subjective evaluation of beer drinkability and the degree of stomach fullness were found to correlate with the relaxed cross-sectional area of the pylorus antrum measured by real-time ultrasonography. Five kinds of beer with a different malt/adjuncts ratio and degree of attenuation were used. Each beer was given to 9 healthy volunteers at the rate of 3 ml/kg/15 min, and they each recorded the degree of stomach fullness, desire to drink and tastiness every 30 min. With increasing volume drunk, the degree of tastiness and desire to drink were lowered, and the degree of stomach fullness raised. The relaxed cross-sectional area of the pylorus antrum measured by an ultrasonic image analyzer every 30 min was highly correlated with the degree of stomach fullness, tastiness of the beer, and desire to drink (p = 0.0021, < 0.0001, 0.001). The beer giving the lowest degree of stomach fullness was appraised to be tasty and highly drinkable. These findings suggest that the rate of gastric emptying is one of the factors determining the drinkability of beer, and that measurement of the relaxed cross-sectional area of the pylorus antrum is useful to evaluate stomach fullness during beer drinking.

Adult↗
PubMed1991

Beer versus mixed-drink consumption at fraternity parties: a time and place for low-alcohol alternatives.

Blood alcohol concentration (BAC) measurements were taken of university students entering and exiting three fraternity parties: during each party, the rates of drinking beer and mixed drinks were monitored. The parties choose beer or mixed drinks to consume exclusively throughout the evening at no cost. Unbeknownst to the subjects, the following conditions were manipulated across successive parties: (1) at the first party (64 males and 43 females) the beer alternative had standard alcohol content (i.e., 7% alcohol by volume), (2) at the second party (70 males and 48 females) the beer was a low-alcohol beer (3% alcohol) and (3) at the third party (53 males and 41 females) the partiers were randomly assigned to a regular alcohol content conditions of beer or mixed drinks or to a low-alcohol content condition (i.e., 3% beer or mixed drinks made with 7/8-oz of distilled spirits). Since those assigned to the low-alcohol conditions did not consume more beverages than those in the regular alcohol conditions, a titration hypothesis was not supported and the exit BACs were significantly lower for partiers in the low-alcohol conditions. When females drank at the same rate as males, their exit BACs were significantly higher than those of males. Implications for DWI prevention are discussed.

Accidents, Traffic↗
PubMed1999

Beer drinking accounts for most of the hazardous alcohol consumption reported in the United States.

OBJECTIVE: Patterns and correlates of hazardous drinking, defined as occasions in which five or more drinks were consumed in a day, were compared for wine, beer and distilled spirits. METHOD: From a probability sample of the U.S. adult household population, 2,817 respondents who had consumed at least one drink in the previous year were selected for analysis. RESULTS: The results show that, in the U.S., beer accounts for the bulk of alcohol consumed by the heaviest drinkers. Beer also accounts for a disproportionate share of hazardous drinking. Logistic regression analyses revealed that drinkers who consume beer in a hazardous fashion at least monthly are more likely to be young, male and unmarried, and less likely to be black than are other drinkers. Hazardous beer consumption is more predictive of alcohol-related problems than hazardous consumption of wine or spirits. CONCLUSIONS: Three potential explanations for the results are considered: advertising, beer-drinking subcultures and risk compensation. Additional research is urged in order to better specify the causal role of these and other factors in hazardous beer drinking.

Adult↗
PubMed1987

Voluntary beer drinking in rats.

Female Long-Evans rats (N = 30) were tested for individual preference for beer for a 24 h period and then assigned to beer (BR) (N = 15) or control (CT) (N = 15) groups according to preference. BR animals were allowed ad libitum access to beer, food and water; while CT animals were allowed ad libitum access to food and water for a 21 day period. Beer, food and water consumption levels were recorded daily. Animals were weighed every other day. Blood alcohol levels and pattern of drinking (comparison of beer consumption in light versus dark cycles) were measured in a separate set of animals. At the end of 21 days of drinking, beer was withdrawn from the BR group and all animals were observed for withdrawal symptomology. BR animals ate more food than CT animals days 2 through 13, and then ate less than CT on days 17 through 21. BR animals drank more "total water" (drinking water plus water in beer) than CT. Body weights were not affected. Changes in body temperatures and tail flick latency, and notation of hyperactivity, shivering and tremoring during 8 hours of withdrawal indicated that BR animals were dependent on alcohol.

Alcohol Drinking↗
PubMed1985

Fortification of sorghum beer with thiamin.

The consumption of indigenous cereal-based fermented beer is widespread throughout Africa and other parts of the world. In some countries such beer is brewed commercially as well as at home. As evidence of beri-beri may occur in habitual consumers of the beer, the thiamin content of beer brewed commercially from a mixture of sorghum and maize was investigated. Thiamin concentration in beer averaged 0.33 mg/l, with more than 95% in the cellular fraction, mainly live yeast cells. The thiamin in the cells is not generally available for absorption and the cells take up thiamin added to the beer. At low concentrations (0.25-0.5 mg/l) up to 90% of added 14C-thiamin was taken up by the cells but with concentrations in excess of 2.5 mg/l, the uptake was less than 30%. These results indicate that fortification of sorghum beer with thiamin is feasible. The addition of 2.5 mg/l would supply up to 1.6 mg of absorbable thiamin and thus meet the recommended daily allowance in the target group of habitual consumers.

Beer↗
PubMed1978

[Current knowledge on the organoleptic characteristics of beer].

This important subject will be considered in three parts: I. Tasting procedures. As there is no standard nomenclature in brewing for describing the organoleptic properties, each brewery has devised its own terminology for this purpose. Four organizations: the European Brewery Convention (EBC), the American Society of Brewing Chemists (ASBC), the Master Brewers Association of America (MBAA) and the Institute of Brewing have collaborated to produce a standard terminology for beer tasting suitable for international use. Different tasting procedures, as well as their statistical interpretation will be discussed. II. Threshold values of certain compounds. Several hundred compounds present in beer have been studied and their threshold values are known for certain types of beer. Particular methods of tasting have been tried out to determine precisely the threshold value of a pure compound in beer. III. Correlation between the tasting results and the physico-chemical properties of beer. The application of statistical methods of analysis to the testing results and physico-chemical properties of different beers has allowed the importance of certain constituants of these beers to be estimated.

Beer↗