Investigation of overfoaming activities and gushing mechanisms of individual beer ingredients as model substances in bottled carbonated water

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Researchers from several disciplines are interested in understanding the spontaneous and eruptive overfoaming (gushing) of carbonated beverages, as it is an essential problem of both brewing and beverage industries. In order to understand the mechanism(s) taking place in gushing-beer, several beer ingredients have been investigated as model substances in much simpler matrix of carbonated water. For this purpose, sinapic acid, vanillic acid, ferulic acid, cinnamic acid and palmitic acid have been chosen as model beer ingredients. Gushing formation of the investigated beer ingredients depends on degree of stabilized solvated molecular carbon dioxide in water. For this purpose, functional groups which are capable of forming hydrogen bonds with electronegative oxygen atoms of carbon dioxide are needed. However, solubility of substances plays an important role in abundance of these functional groups in undissociated form to interact further with solvated molecular carbon dioxide. The reported data provide valuable insights into the gushing problem and help to understand its formation pathways. Each gushing-positive substance has an individual mechanism related to its structural conformation and solubility level. Therefore, possible gushing mechanisms have been proposed with respect to structural changes in model substances to clarify the differences in observed overfoaming and gushing stability levels.

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Beer is one of the most popular alcoholic beverages around the world. It has a very long history, even beyond the record of civilization. Yeast, malt, hops, and water are the main ingredients for beer brewing. Sometimes, other starch adjuncts like rice and syrup are also used as the brewing materials. The brewing process contains several steps, including mashing, fermentation, filtration, and filling. Hops are indispensable in beer, as they supply beer with flavor compounds, antibacterial ability, and health effects. Amylases (α-amylase, β-amylase, α-1,4-glucan glucohydrolase, and deramifying enzyme) and proteases are two main enzymes used in beer brewing. Yeast is the soul of beer brewing, as it plays a decisive role in beer quality. Based on the yeast used in the brewing, the most recognized categories of beer are ale and lager. Because the color, foam, and taste are the critical features that affect the quality of beer, white and smooth foam not only gives drinkers a pleasant feeling and excellent flavor, but also avoids the loss of flavor and direct oxidation. Compounds like CO2, metal ions, proteins, and flavor substances in beer have positive impacts, whereas lipids and alcohols have negative impacts on formation and stabilization of beer foam. Among these compounds, protein Z was the first protein found in beer and has the character of stabilizing beer foam. Moreover, saccharides, as the most abundant material in beer other than water, not only can maintain the nonbiological stability of beer, but also play a very important role in maintaining foam stability. Finally, stability is always the goal for beer brewers, and it is usually referred to as biological stability, nonbiological stability, foam stability, and flavor stability.
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Clanek se zabýva kinetikou narůstu tlaku v hrdlovem prostoru lahve naplněne syceným napojem po rychlem otevřeni a uzavřeni výpustniho ventilu, umistěneho na hrdle lahve. Rychlost narůstu tlaku se měřila elektronickým tlakoměrem s rychlou odezvou. Unik CO2 se take inicioval elektrolýzou nebo vloženim poroviteho materialu do piva. Narůst tlaku v hrdle lahve lze popsat jednoduchou kinetickou rovnici s dvěma parametry, pocatecni rychlosti narůstu tlaku a konstantou popisujici potlaceni uniku bublin z povrchu pevných castic. Při trvalem odstraňovani mikrobublinek CO2 vazaných na povrch pevneho materialu např. vytrvalým třepanim je narůst tlaku omezen rozpustnosti oxidu uhliciteho a teplotou. Tato technika take umožňuje testovat vliv pivovarských substratů a procesnich parametrů na nachylnost k přepěněni piva v lahvi a vyhledavat lahve s naruseným povrchem po naplněni lahvi sycenou vodou.
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Pro předpověď nachylnosti piva ke gushingu lze využit měřeni narůstu tlaku v hrdlovem prostoru po odpustěni tlaku z lahve a jejim opětovným uzavřenim. Významným parametrem je pocatecni hodnota narůstu (kPa/min), nebo hodnota tlaku po 1 min od opětovneho uzavřeni lahve tzv. PG1. Pivo s hodnotou PG1 > 50 kPa se považuje za nachylne k přepěňovani, pivo s hodnotou nad 120 kPa silně vystřikuje, nebo přeteka z lahve. Piva dlouhodobě skladovana v klidu i temnu při 20 oC nevykazovala gushing ani po 11 měsicich skladovani, ale výskyt gushingu se zvysoval s dobou třepani a skladovani piva. Přidavkem zakalotvorných latek např. roztoků taninu a želatiny k sycene vodě nebo pivu se podařilo třepanim vyvolat přepěňovani. Proto předpokladame, že gushing může vznikat i ze sloucenin, přirozeně se vyskytujicich pivu, jako jsou bilkoviny i třisloviny.
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In this study, field-grown barley was artificially infected during the heading stage with three Fusarium species, F. culmorum, F. graminearum, and F. poae. The objective was to investigate possible differences among Fusarium species in terms of how severely they affect the quality of barley under Finnish field conditions. Moreover, we studied the effects of heavy infection on corresponding malt quality. Field trials were carried out with two different barley cultivars at two experimental farms. Spike samples collected during the growing period were analyzed for Fusarium infection and moisture content. Total precipitation and temperature data were collected daily. In addition, the harvested barley samples were analyzed for overall microbial flora and for mycotoxins. The infection rate and the amount of mycotoxins produced in the barley samples differed among species. F. graminearum was found to have the most negative effects on barley quality in terms of the studied parameters. Samples were malted in laboratory scale. All three Fusarium species increased the gushing potential of malt. Heavy fungal infection increased the enzyme activities in malt resulting in darker wort color and increased soluble nitrogen and free amino nitrogen content. However, high Fusarium contamination reduced lautering performance.
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J. Inst. Brew. 111(2), 105–111, 2005 Fungal infection of barley and malt, particularly by strains of the genus Fusarium, is known to be a direct cause of beer gushing. We have shown previously that small fungal proteins, hydropho-bins, isolated from strains of the genera Fusarium, Nigrospora and Trichoderma act as gushing factors in beer. A hydrophobin concentration as low as 0.003 ppm was sufficient to induce gush-ing. The gushing-inducing abilities of the isolated hydrophobins varied probably due to their structural differences. The hydro-phobins did not affect beer foam stability. A correlation was ob-served between the hydrophobin level analyzed by the hydro-phobin ELISA developed and the gushing potential of malt. The risk of gushing was found to increase with hydrophobin concen-trations above 250 µg/g malt. The levels of hydrophobin and the Fusarium mycotoxin deoxynivalenol (DON) in malts were not correlated which indicated that the formation of those two fun-gal metabolites may not be linked. Furthermore, we did not ob-serve a correlation between the DON content and the gushing potential of the malt studied. Our observations suggest that the accuracy of predicting gushing could be improved by measuring the amount of the actual gushing factors, hydrophobins, in bar-ley or malt.
Primary beer gushing is defined as the wild and uncontrolled overfoaming of packaged beer induced by contaminated raw materials as barley and malt. It is generally admitted that most probably amphipathic molecules such as hydrophobins and non-specifi c lipid transfer proteins (ns-LTPs) are responsible for this phenomenon. These molecules are synthesized by moulds and by vegetal tissues respectively in order to modify the polarity of surfaces and the solubility of molecules. At present, hydrophobins are extensively studied as they are considered as the major responsible molecules involved in primary gushing. Although a strong reduction (more than 85 %) of the initial concentration of hydrophobins present in malt occurs during the brewing process, the residualquantity remaining in fi nished beer is suffi cient to provoke the gushing of packaged beer and the subsequent dramatic commercial damages to a particular beer brand. This review compiles the relevant fundamental physical and chemical properties of CO2 and experimental observations at laboratory and pilot scale. A plausible mechanism of primary gushing is presented. It is based on the effective role of hydrophobins association to CO2 nanobubbles, acting as "nanobombs" and perhaps as "nucleation sites" causing effects from overfoaming to strong gushing depending on the concentration and the carbonation rate. In beer formation of CO2 bubbles proceeds through heterogeneous nucleation. The rapid heterogeneous nucleation initiated at the opening of the container in excessively gushing beer suggests the the presence of catalysts to overcome the energy barriers. Since hydrophobin molecules are able to bind to carbonic acid, they prevent part of the CO2 from dissolution. These structures will aggregate in timeframes of days or even weeks depending on the beer by forming nanobubbles of a typical critical radius. The internal pressure of these nanobubbles is proportional to the carbonation pressure of gaseous CO 2 in the container at fi lling (about 3.0 till 4.0 ATU of CO 2 ). At the opening of the container, the difference of partial pressure of carbonic acid in the bottle and in the atmosphere provokes the explosion of these nanobubbles and results in a strong gushing effect.
Nickel or iron, though only in association with isohumulone, will contribute to overfoaming in beer; cobalt, alone or with isohumulone, will not. Thus, whilst these three metals all increase foam stability and in fact, when present, become concentrated in the foam, cobalt differs from the two others in its relation to overfoaming.
Gushing is reviewed with particular attention to the nucleole theory. Evidence derived from phenomena comparable with gushing occurring in fields unrelated to brewing is discussed.
The Research Center Weihenstephan for Brewing and Food Quality has developed a method, based on physical chemistry, for rapid and reliable assessment of colloidal stability by analysing the streaming current potential and surface charge density of particles in filtered beers. In food analysis, the measuring technology is successfully used for fining of fruit juices, for gushing control in sparkling wine production and to determine the influence of clarifying agents on particle charge in beer. Only the surface charge density of particles has been hitherto determined with this method. The new charge titration method developed by Titze & Ilberg additionally makes it possible to reproducibly measure the streaming potential. This first part presents the fundamentals in a simplified manner. In part 2, possibilities of using this method in the brewing industry will be described.
Eine der wichtigsten Eigenschaften des Würzekochens ist die Koagulation des Eiweißes. Der nach dem Kochen noch vorhandene koagulierbare Stickstoff beeinflusst den Biercharakter ebenso wie die kolloidale Stabilität. Seine Bestimmung erfolgt heute meist nach den Methoden von Kjeldahl. In diesem Artikel wird die Möglichkeit der Ladungstitrationsmethode zur Beschreibung der Konzentrationsänderung des koagulierbaren Stickstoffs während des Kochvorgangs vorgestellt. Die Ladungstitration wurde bereits erfolgreich zur Beschreibung der kolloidalen Stabilität des Bieres angewandt.
The relationship between the chemical structure of model substances (fatty acids, monoacylglycerols, and fatty alcohols) and gushing development and suppression was elucidated. Gushing increased with increasing aliphatic chain length, beginning with a minimum length. Mono- and polyunsaturated cis-fatty acids such as oleic acid (C18:1), linoleic acid (C18:2), linolenic acid (C18:3), and arachidonic acid (C20:4) were identified as gushing-negative. These unsaturated fatty acids completely suppressed gushing, which was induced by palmitic acid and malt extract. The trans-isomer of oleic acid (C18:1), the trans-fatty acid elaidic acid (C18:1), which is unsaturated but nearly linear, could not suppress gushing and actually caused it. The results showed that the gushing-suppressing effect of unsaturated cis-fatty acids (C18 and C20) resulted from the physical orientation of the bend(s) in the aliphatic chain. In contrast to the other unsaturated cis-fatty acids, the monounsaturated cis-fatty acid nervonic acid (C24:1) did cause gushing. This was explained by the fact that the rectilinear aliphatic chain (from the head group to the fifteenth C atom) was long enough to enable intensive hydrophobic interaction, which allowed close agglomeration of the compounds. In this context, the melting point proved to be an interesting physicochemical parameter for gushing: all examined fatty substances with a melting point higher than approx. 40°C caused gushing. The model substances were successfully applied to find new and more complex gushing structures. A new amino acid sequence (NH2-Ile-Ile-Ile-Ile-Ile-Asp-Asp-COOH) was chosen to synthesize a peptide that caused distinct overfoaming. Gushing caused by this peptide was completely prevented by linoleic acid. The results of this study demonstrate that the model substances tested could be helpful in the identification of well-known substances in beer and beverages for research into their gushing characteristics.
The phenomenon of gushing, characterized by the spontaneous overfoaming of carbonated beverages directly after opening a bottle (or a can), can still be a problem for the brewing and beverage industry worldwide. Due to its sudden and partly eruptive character, gushing can be detrimental to the image of the industry when it occurs in the hands of the consumer. Gushing is a complex phenomenon, induced by a variety of gushing factors of the raw materials and in the production process. A reliable methodology to avoid gushing is not yet available. Nevertheless, the obvious measure to prevent or at least minimize gushing is to assess the raw materials for their risk of gushing before they are processed further in production. Thus, the investigation of gushing analysis plays a particular role in the industry to prevent gushing and also in research to get more cognition on this phenomenon. This article gives a review of gushing with the focus on analysis. In current gushing tests, the overfoaming amount of bottled and carbonated extracts of the examined raw materials is used to determine the extent of the gushing potential. However, these analytical methods have disadvantages. The overfoaming amount can fluctuate, making it difficult to quantify the gushing potential precisely and the performance of these tests takes time (some days), which can lead to the unfavourable situation where the raw materials have already been processed before gushing could be detected. Therefore, the thematic priority of this review article is to present new ideas to quantify gushing more precisely and novel analytical approaches for the prediction of gushing by applying combined particle analysis.
The complex phenomenon of gushing occurring in carbonized beverages has been investigated in order to better understand the mechanism and to give input for further research to introduce preventive measures for the industry. The knowledge that microbubbles are stabilized through surface active substances, and in this form can induce gushing, was used to examine a selection of representative surfactants. For the analysis, a particle size distribution method was used which enabled to detect particles at nanometer level, starting from 0.8 nm onwards. The experiments using pure aliphatic surfactants (DTAC, TTAC, CTAC, ODTABr, CPC, SDS, and Tween 20) revealed that only CTAC, solved in CO2 containing table water at 2 g/l (above the critical micellar concentration), induced gushing. CTAC therefore was characterized as gushing typical by its structure (length of hydrophobic part and kind of head group). Gushing caused by CTAC was not only observed through shaking of the bottles, but also without any shaking at all. The latter observed fact was not explainable by the mechanical incorporation of CO2 bubbles stabilized by CTAC monomers, but generally through stabilized microbubbles formed by a mechanism that is yet unknown. The particle size analysis revealed that particles grow, starting from ca. 10 nm to reach several 100 nm, if sufficient amounts of CO2 molecules are present. The growth was accelerated by a mild shaking of the bottles. The results pointed out that CTAC micelles grow by diffusion of CO2 molecules into the hydrophobic core. Thereby, microbubbles are formed and stabilized through CTAC monomers at the interface gas/liquid, and can grow to gushing-relevant sizes of several 100 nm.
This work investigated the gushing phenomenon in wort samples by applying commonly used gushing tests (Weihenstephaner and modified Carlsberg test) in order to identify conditions for the development of gushing. The mashing and boiling procedures were modified (Weihenstephaner test), and the amount of wort and time of shaking of the bottle were increased (modified Carlsberg test). For the experiments one malt sample was applied that was identified as gushing-positive (Weihenstephaner test). A changing pattern of the mashing process revealed that gushing was induced after heating up to 97 °C while no gushing was observed until 80 °C. Heating up the mash from 80 °C to 100 °C and boiling it for 5 min afterwards sufficed for gushing to be induced in the wort sample. From the applied malt sample it was possible to produce not only a gushing-positive wort but also a gushing-negative one. By mixing these wort samples, gushing could be reduced, or even entirely suppressed, applying a volume of only 10 % v/v of the gushing-negative sample. The gushing-positive wort could only induce gushing in amounts of above a critical level. Gushing started to develop after a mild shaking for 10 h (modified Carlsberg test) and increased significantly after 20 h of shaking. The results demonstrated that the temperature of the mash is a decisive parameter for the development of gushing.
In this work it was first shown how to quantify the gushing potential of malt with a modification of a common gushing test. Today there exist two acknowledged gushing tests for the brewing industry (Modified Carlsberg Test and Weihenstephaner Test). Both analytical methods use the overfoaming amount of a test-specific produced carbonated wort to determine the gushing potential of malt. Unfortunately the overfoaming amount can vary statistically in a way that this parameter can “only” be used for qualitative information if the malt has a potential for gushing or not and if one malt has a higher or lower gushing potential than another one; but a precise quantitative comparison for example between two malts which both have a gushing potential is difficult. This was the focus of this investigation. With two gushing-positive samples (malt A and B) it could be shown that with an increase of the concentration of malt solutes a certain point is reached where gushing appears the first time determined by the overfoaming amount applied the Modified Carlsberg Test. For malt A a frequently higher gushing potential (f ≥ 5) than for malt B was identified. These results were verified by determining the amount of a gushing suppressing hop product that led gushing to zero by having a constant concentration of malt solutes. The results demonstrated enhanced gushing analyses to quantify the gushing potential reproducibly, not by the overfoaming amount but by the “zero point” where gushing begins (concentration of malt solutes) or is neutralized (amount of hop product). The introduced methods enable the chance for the first time to quantify the gushing potential of malt more precisely.
Particle analysis and its potential in describing the physico-chemical characteristics of particles in beer were investigated. It was the aim to figure out the feasibility for its application in brewing and beverage science. To describe existing problems in the beverage industry caused by insufficient physico-chemical stability of the beverages a rule of great generality according to the particle characteristics was also defined as follows: Beverages are liquids, in which colloids, also called particles, exist in disperged (e.g. beer) or emulsified (e.g. milk) form. One main particle characteristic is the surface. This can be seen in many interfacial phenomena, like the surface potential. Mathematically it was shown, that especially for small particles the ratio between surface and volume increases. Surfaces carry electric charges, which terminate or change the physicochemical characteristics of the particles. By combining (1) the particle charge detection with polyelectrolyte titration for determining the surface charge, the surface potential and charge density of particles with (2) the particle size analysis by dynamic stray light to analyze the particle size and particle size distribution, the particles could be characterized. The results, conducted with the help of a Forcier test, revealed that with the increased aging of beer the particle charge, measured by the titrated volume, as well as the surface potential decrease. Both dimensions are in a linear relation with a coefficient of determination of R2 = 0.9611. The results could not explain if the decrease has been caused by the reduction of particle surfaces due to agglomeration or by a significant loss of surface charges of the particles. However, using a particle size measurement, it was found out that small particles (sizes < 50 nm) disappeared and larger particles with sizes from 700 nm to 2000 nm occurred. So it could be demonstrated that the coarsening of particles was caused by agglomeration. In addition to that, the mechanism of forming a 1:1 stoichiometrical charge complex was graphically displayed by the particle size measurement. The highest coefficients of determination (R2 = 0.9997) were found for the titrated volume and the concentration of beer in a dilution series by mixing beer and water, which shows the use of particle charge titration for quantitative determination. In contrast to that, it could be illustrated by nearly identical particle size distribution curves at different concentration levels that it is not possible to “quantify” the detected particles by using only particle size measurement. Therefore, the particle analysis was introduced as a combined method. Due to the statistically good results of this particle analysis, future experiments should involve impacts on the colloidal stability of filtration or flash pasteurization in the beverage industry to get more information in the area of physico-chemical stability of beverages. Besides further experiments, interlaboratory tests should be conducted additionally to utilize the presented particle analysis for the brewing and beverage industry.
Combined particle analysis was applied as a tool to predict gushing in alcohol-free beverage products. Gushing is known as spontaneous overfoaming of carbonated beverages that is an intermittent problem for brewers and the beverage industry. Therefore, preventive tests to examine raw materials for their gushing risk are of interest for the industry. Previously, the focus of gushing tests was on the overfoaming of carbonated samples in specifically shaken bottles, after which the amount of overfoaming was recorded as the measure of gushing. As these tests require a number of days to be performed, it often happens that the raw materials have already been processed before the results are available. Here the combined particle analysis is presented as a “real time” alternative to such tests. This testing methodology was applied in beverage products (for producing spritzers) where it was shown that this analysis was successful in predicting gushing. In the test samples for producing apple spritzers putative gushing causing particles with sizes of only 1–2 nm were identified. Significantly higher stray light intensities for these particles with sizes of 1–2 nm were detected for the gushing-positive compared to gushing negative samples. The particle charge titration method revealed higher titrated volumes for the gushing-positive samples (to neutralize the entire particle surface charge) than for the gushing-negative ones. Therefore, the higher titrated volumes were associated with significantly higher amounts of 1–2 nm-particles. Accordingly the titrated volume for charge neutralization was proposed as measurement parameter to “quantify” gushing-relevant 1–2 nm-particles in order to estimate the gushing propensity. In further beverage products (for producing apple-cherry-spritzers) small particles were not detected, which explains why considerably lower titrated volumes were used and no gushing was observed. The results demonstrate that the particle size and the particle surface charge are promising analytical parameters to predict the gushing propensity of beverage products.
Risks associated with mycotoxin contamination of cereals, that are included in the ten major staple foods and greatly contribute to the dietary energy intake, are of worldwide relevance. In small grain cereals, mycotoxins are produced by fungi such as Aspergillus, Penicillium, Alternaria and Fusarium that colonize the plant in the field and can grow during the post-harvest period, producing several classes of mycotoxins. The identification of mycotoxigenic fungal species and strains is essential for developing effective strategies for control. For this purpose, genetic traceability has proved to be a valuable tool that can be applied along the whole production chain, starting in the field for early diagnosis of FHB (Fusarium Head Blight) disease to the final processing steps, such as malting or pasta making. In this paper, DNA-based analytical tools that are currently available for the identification and quantification of mycotoxigenic fungal species and strains are reviewed, with particular emphasis on Fusarium, and their possible applications in mycotoxin control in small grain cereal chains are discussed.
In bright beers, the formation of haze is a serious quality problem, which places limitations on the storage life of the product. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) immunoblot analysis using an antiserum that was raised against a silica eluate (SE) protein fraction (obtained from silica gel, used for the colloidal stabilisation of beer), detected a range of protein bands in barley, malt, beer and haze. A polymorphism was observed in which some barley varieties contained a molecular weight (MW) ∼12,000 band (SE +ve) while in other varieties this band was absent (SE −ve). A survey of 219 Australian and international barley varieties, including a comprehensive selection of current and past malting varieties, identified 181 varieties as SE +ve, and 38 varieties as SE −ve. Previous pilot brewing trials demonstrated that SE −ve varieties are desirable as the beer brewed from the malt of these varieties formed less haze after accelerated ageing than beers brewed using SE +ve malt varieties. The genetic basis for the absence of the SE protein was conferred by a recessive allele at a single locus. Interval mapping analysis showed that the MW ∼12,000 band mapped to the short arm of chromosome 3H.
During ale fermentation there was an accumulation of total and hydrophobic polypeptides in the foam relative to the wort. Comparisons were made not only of the total and hydrophobic polypeptide contents but also of the molecular weights of these polypeptides present in wort, partially fermented wort and its concomitant foam. Wort, fermented wort and foam fractions had very similar polypeptide compositions with a major group having molecular weights of 40–43 kDa. Material of molecular weight in the range of 5–17 kDa and at 66 kDa was also detected. The polypeptides accumulated in foam displayed both hydrophobic and non-hydrophobic character. The presence of yeast polypeptides in foam was confirmed. Comparison was also made between the fermentations of 10°Plato and 15°Plato wort. The results of the work may contribute to a better understanding of the mechanism of foam formation during beer fermentation, leading to reduced foaming and enabling an increase in the working capacities of fermenters. Copyright © 2004 Society of Chemical Industry
Colloidal haze reduces beer quality considerably. Four haze samples were analyzed by two-dimensional gel electrophoresis (2DE) in order to identify haze-active proteins. Several protein spots were observed in all of the four haze samples. Using mass spectrometry analysis followed by a database search identified these spots as barley dimeric alpha-amylase inhibitor (BDAI-1), CMb component of tetrameric alpha-amylase inhibitor (CMb) and trypsin inhibitor CMe precursor (CMe). These proteins were considered to be haze-active. Since haze-active proteins are adsorbed by silica gel in the beer filtration process, we eluted proteins adsorbed onto silica gel (PAS) and identified their species. These major PAS were identified as protein Z4, protein Z7 and trypsin/amylase inhibitor pUP13 (TAI), rather than BDAI-1, CMb and CMe. Furthermore, we analyzed proline compositions in the beer proteins, PAS and the haze proteins. Consequently, we found that the proline compositions of PAS were higher (ca. 20 mol%) than those in the beer proteins (ca. 10 mol%), although those of the haze-active proteins such as BDAI-1, CMb and CMe were 6.6–8.7 mol%. Our results suggest that BDAI-1, CMb and CMe are not predominant haze-active proteins, but growth factors of beer colloidal haze.
Long-term stability is one of the most important quality criteria of beer. Three groups of measuring methods are available for its determination: real time tests, predictive tests and indicative tests. One of the most common methods is the predictive forcing test, which is a time-consuming method for accelerating beer ageing, e.g., at 0°C and 60°C. Two ways exist to perform this test: (1) follow-up of haze development and determination of the lag phase or (2) the measurement of haze values after several days. The first option was evaluated by performing a long-term Forcing test over a period of 4 months by analyzing a bottom-fermented beer. It was shown that the haze curve followed a typical course with a lag phase, an increase phase and a station-ary phase. Significant differences between the measurement after the cooling and the warm period were shown. In search of quicker methods and more accurate predictive indicators, the charge titration method was developed as an alternative to deter-mine the particle charge of filtered beers, whereupon the rela-tionship was elucidated between the increase in hazing and de-crease of potential along with the advanced aging of beer. The results showed that with increased particle size due to agglom-eration, the total charge decreased. In this array of trials, two differently stabilized beers were examined. Although both beers showed different haze values in the beginning (0.32 EBC and 1.30 EBC), the less stabilized beer had only 10 warm days and in contrast the beer with the good stabilization had over 20 warm days. With the help of the total charge, predictions were possible regarding the long-term stability of the beer.
Qualitative effects of Botrytis cinerea infection were studied by comparing the foaming properties of Champagnes obtained from healthy grapes with those from grapes infected by B cinerea. This is of particular interest when it is considered that the foaming properties of Champagne wines are important in terms of product attractiveness for the consumer. Experiments using artificial viewing equipment clearly showed the dramatic effects on Champagne foam characteristics when grape berries were highly infected. The speed at which liquid separated from the foam (expressed as liquid height LS) in the glass depended largely on the level of infection for Chardonnary and Pinot noir wines (+268% for Chardonnary wines at 40% infection and +627% for Pinot noir wines at 20% infection). B cinerea infection reduced the time (LT) at which liquid first appeared in the glass; for Pinot noir wines an infection level of 20% caused very rapid drainage. The time of pouring (PT, ie the time to fill the glass under controlled conditions) also diminished considerably at an infection level of 20% for both Pinot noir and Pinot meunier wines (−74 and −58% respectively). Mouldiness considerably altered the foam height observed 80 s (H80) after the start of pouring (−83% for Pinot noir and −89% for Pinot meunier at 20% infection). Champagne foamability was also quantified using a sparging technique to standardise effervescence. Foamability suffered considerably (−60 to −65%) when the B cinerea infection level was 20% as compared to control Champagnes. All wines studied had low and very similar protein contents. Differences in the concentrations of these compounds, which are generally implicated in the formation of foam in sparkling wines, could not explain the differences in Champagne foaming properties observed here.© 2001 Society of Chemical Industry
Unpasteurized lager beer samples from a commercial brewery were treated either by high hydrostatic pressure (HHP; 200, 250, 300, 350 MPa for 3 and 5 min at 20 °C) or by conventional heat pasteurization (60 °C for 15 min). The main attributes of the beer, such as ethanol content, extract and pH, were not affected by either treatment; however HHP and heat pasteurization affected colour, chill haze, protein sensitivity and bitterness. Change in bitterness was higher in conventional heat pasteurization, but pressures up to 300 MPa had no significant affect on bitterness. Although more studies should be carried out to investigate the effects of HHP treatment on different types of lagers and ales, our results revealed that HHP could be successfully used to process beer, even at temperatures well below those required for heat pasteurization, without affecting some of the quality attributes. Copyright © 2005 Society of Chemical Industry
Previous pilot brewing trials have demonstrated that in the absence of a molecular weight (MW) ∼12,000 (barley silica eluate (SE) protein), the beer brewed from the malt of these SE −ve varieties formed less haze after accelerated ageing than beers brewed using SE +ve malt varieties. The previously described SE protein was characterised using comparative two-dimensional (2-D) gel electrophoresis immunoblots of barley seed extracts from both SE +ve and SE −ve varieties. The SE protein spot identified was excised and its partial sequence determined, after in-gel cleavage using trypsin and separation of the resulting fragments by reversed-phase high performance liquid chromatography (HPLC). N-terminal sequence analysis of the tryptic peptides from SE +ve and SE −ve varieties identified the SE protein as the barley trypsin inhibitor-CMe precursor (BTI-CMe). The mature BTI-CMe protein is 13.3 kDa and its functional gene is located on chromosome 3H. Cloning of the BTI-CMe protein demonstrated that both SE −ve and SE +ve barley varieties contain a BTI-CMe protein family member that is similar but has a consistently different sequence, primarily in the last 30 amino acid residues of their C-termini.
The brewing of beer is a very traditional process, based upon a complex endogenous enzymology occurring during the malting of grain, mashing of grist and fermentation. The relevant cereal-derived enzymes that are involved are reviewed. It is likely that the production of alcoholic beverages in breweries in the projected future will assume different paradigms, procedures which are already realistic for the production of flavoured alcoholic beverages (malternatives) and “near-beer” drinks (happoshu and other beer-like beverages) in Japan. A range of exogenous enzymes—such as glucanases, acetolactate decarboxylase and prolyl endopeptidase—are available for enhancement of the existing brewing process.
Measurements of dissolved CO(2) concentrations from Champagne bottles initially holding the same CO(2) level after having been elaborated (close to 11.5 g L(-1)), but having experienced different periods of aging after having been corked with natural cork stoppers, were done. Losses of dissolved CO(2) close to 3.5 g L(-1) experienced by the oldest Champagne samples aged for about 75 months were reported. This very significant loss of dissolved CO(2) was logically interpreted as a consequence of the continuous diffusion of gaseous CO(2) through the pores of the cork stopper. By combining the diffusion principle through a porous medium with Henry's law (which links the solubility of a gas species in a liquid medium with its partial pressure in the vapor phase), a multiparameter model was built that provides the dissolved CO(2) content found in Champagne during its whole aging period. Both Champagne temperature and bottle volume were found to be key parameters with regard to the kinetics of CO(2) losses through the cork.
Fusarium toxins, secondary metabolites of toxinogenic Fusarium species, are found in a range of cereal grains. In this study the occurrence of the most commonest Fusarium toxins, namely nivalenol (NIV), deoxynivalenol (DON), deoxynivalenol-3-glucoside, fusarenon-X, 3- and 15-acetyldeoxynivalenol, HT-2 and T-2 toxins and zearalenone, in various barley cultivars harvested in 2005-2008 was monitored. The impact of weather, locality, fungicide treatment and barley cultivar (hulless or covered) on contamination was evaluated. The transfer of these mycotoxins into malt was assessed. The most prevalent toxin was DON, which was found in 83% of samples (maximum level 180 µg kg(-1)), while HT-2 was detected in 62% of samples (maximum level 716 µg kg(-1)). Using analysis of covariance, weather was found to be the key factor in all years (P < 0.001). A relationship between cultivar and contamination was confirmed only for HT-2 (P < 0.001) and T-2 (P = 0.037), with higher levels of these toxins being observed in hulless cultivars. With the exception of NIV (P = 0.008), no significant relationship was found between fungicide treatment and contamination. No distinct trend regarding DON levels in malt was found, with both decreases and increases occurring. The results show an inter-annual variation in mycotoxin occurrence in barley cultivars as well as differences in contamination of malt produced from fungicide-treated and untreated barley.
Filtered bright and unfiltered hazy lager beer samples were either treated with high hydrostatic pressure (200, 250, 300, 350 MPa for 3, 5 and 10 min at 10°C and 20°C) or conventional heat pasteurization (60°C for 15 min). Treatments did not affect ethanol, extract, fermentation degree, density and pH in comparison with untreated beers. Both treatments produced microbiologically stable products. Bitterness, color, protein sensitivity and chill haze parameters were affected by both the HHP and heat treatment. A storage period of 56 days showed that HHP and heat pasteurization had similar results in terms of pH and color. However, HHP treated samples had lower bitterness and protein sensitivity and higher chill haze values than the heat pasteurized samples which indicates HHP treatment had a positive effect on bitterness and protein sensitivity at the end of the storage period. The microbiological stability of HHP treated beers was comparable with heat-treated beers, and the development of both lactic and acetic acid bacteria was inhibited for 56 days of storage. Unfiltered beer samples had 7. 48, 7.15 and 2.64 log10cfu/ml of total yeasts, total aerobic and lactic acid bacteria counts, respectively. No colony formation of lactic acid bacteria was observed when the samples were pressurized at pressures equal to or higher than 300 MPa at 10°C and 20°C for 5 and 10 min. Total aerobic and total yeasts counts demonstrated more than 6 and 7 log-cycle reduction when pressurized at 350 MPa at 10°C and 20°C for 10 min, respectively. Heat treatment gave similar results in terms of log reductions as HHP.
Everybody has had the experience of a canned carbonated drink overflowing and soiling their clothes. It is difficult to guess the amount of overflow before opening the can, although the phenomenon can be simply explained as the result of the formation of gas bubbles. In this article, we report the surprising result that intensive shaking using ultrasonic vibration can calm this effect in beer. These experiments showed evidence of a memory effect in liquid. The 'calming down' is due to a fine balancing act between a change in the amount of microbubbles (or embryos) and a change in the pattern of their size distribution. Our experimental evidence shows that modification of the pre-existing microbubbles noticeably influences the subsequent nucleation, and this may open a new route to nucleation studies.
We found that hydroxycinnamic acid (HA) glycerol esters such as 1-sinapoyl glycerol and 1-p-coumaroyl glycerol can be synthesized through a direct esterification reaction using a type A feruloyl esterase from Aspergillus niger. The water solubilities of HA glycerol esters were higher than those of the original chemicals. HA glycerol esters absorbed ultraviolet light and scavenged 1,1-diphenyl-2-picrylhydrazyl radicals.
Wildwerden) des Bieres
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Ergebnisse einer Umfrage in deutschen Brauereien zum Thema "Gushing
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Kunert M, Sacher B, and Back W, Ergebnisse einer Umfrage in deutschen Brauereien zum Thema "Gushing". Brauwelt 141: 350-362 (2001).
CO 2 -hydrophobin structures acting as nanobombs wileyonlinelibrary Investigation of overfoaming activities and gushing in beer – Part 1: A critical review of hypotheses and mechanisms
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Deckers SM, Gebruers K, Baggerman G, Lorgouilloux Y, Delcour JA, Michiels C, et al., CO 2 -hydrophobin structures acting as nanobombs c 2013 Society of Chemical Industry J Sci Food Agric (2014) Investigation of overfoaming activities and gushing in beer – Part 1: A critical review of hypotheses and mechanisms. Brew Sci 63:54–61 (2010).
the quality of barley and malt
the quality of barley and malt. J. Am. Soc. Brew. Chem. 63: 43-49 (2005).
Gushing problems caused by calcium oxalate (Part 1). Brauwelt Int
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Zepf M and Geiger E, Gushing problems caused by calcium oxalate (Part 1). Brauwelt Int. 18: 473-475 (2000).
Methodensammlung der Mitteleuropäischen Brautechnischen Analysenkommission Rohstoffe. MEBAK
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Anger HM, ed., Brautechnische Analysenmethoden, Methodensammlung der Mitteleuropäischen Brautechnischen Analysenkommission Rohstoffe. MEBAK, Freising-Weihenstephan, Germany (2006).
Combined particle analysis as a new tool to predict gushing shown with alcohol-free beverage products
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Christian M, Titze J, Ilberg V, and Jacob F, Combined particle analysis as a new tool to predict gushing shown with alcohol-free beverage products. Brew Sci 63: 72-75 (2010).
Enzymatic synthesis of hydroxycinnamic acid glycerol esters using type A feruloyl esterase from Aspergillus niger
  • M Tsuchiyama
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  • H Kawasaki
Tsuchiyama M, Sakamoto T, Taninori S, Murata S, Kawasaki H, Enzymatic synthesis of hydroxycinnamic acid glycerol esters using type A feruloyl esterase from Aspergillus niger, Biosci Biotechnol Biochem 71: 2606-2609 (2007).
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Kastner H, Das "Wildwerden" des Malzbieres. Wochenschr Brauerei 26: 169-170 (1909).
  • E Helm
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  • Das Überschäumen
Helm E and Richardt OC, Das Überschäumen (Wildwerden) des Bieres. Wochenschr Brauerei 55: 89-94 (1938).
Das ‘Wildwerden’ des Malzbieres
  • Kastner
Ergebnisse einer Umfrage in deutschen Brauereien zum Thema ‘Gushing’
  • Kunert
CO2-hydrophobin structures acting as nanobombs in beer - Part 1: A critical review of hypotheses and mechanisms
  • Deckers
Das Überschäumen (Wildwerden) des Bieres
  • Helm
Combined particle analysis as a new tool to predict gushing shown with alcohol-free beverage products
  • Christian