Profile Of Beer Research Articles

Insights on beer volatile profile: Optimization of solid-phase microextraction procedure taking advantage of the comprehensive two-dimensional gas chromatography structured separation.

The aroma profile of beer is crucial for its quality and consumer acceptance, which is modu-lated by a network of variables. The main goal of this study was to optimize solid-phase microextraction experimental parameters (fiber coating, extraction temperature, and time), taking advantage of the comprehensive two-dimensional gas chromatography structured separation. As far as we know, it is the first time that this approach was used to the untargeted and comprehensive study of the beer volatile profile. Decarbonation is a critical sample preparation step, and two conditions were tested: static and under ultrasonic treatment, and the static condition was selected. Considering the conditions that promoted the highest extraction efficiency, the following parameters were selected: poly(dimethylsiloxane)/divinylbenzene fiber coating, at 40ºC, using 10 min of pre-equilibrium followed by 30 min of extraction. Around 700-800 compounds per sample were detected, corresponding to the beer volatile profile. An exploratory application was performed with commercial beers, using a set of 32 compounds with reported impact on beer aroma, in which different patterns can be observed through the structured chromatogram. In summary, the obtained results emphasize the potential of this methodology to allow an in-depth study of volatile molecular composition of beer.

Novel starters for old processes: use of Saccharomyces cerevisiae strains isolated from artisanal sourdough for craft beer production at a brewery scale.

The deliberate inoculation of yeast strains isolated from food matrices such as wine or bread, could allow the transfer of novel properties to beer. In this work, the feasibility of the use of baker's yeast strains as starters for craft beer production has been evaluated at laboratory and brewery scale. Nine out of 12 Saccharomyces cerevisiae strains isolated from artisanal sourdoughs metabolized 2 % maltose, glucose and trehalose and showed growth rates and cell populations higher than those of the brewer's strain Safbrew-S33. Analysis of allelic variation at 12 microsatellite loci clustered seven baker's strains and Safbrew-S33 in the main group of bread isolates. Chemical analyses of beers produced at a brewery scale showed significant differences among the beers produced with the baker's strain S38 or Safbrew-S33, while no significant differences were observed when S38 or the brewer's strain Safbrew-F2 was used for re-fermentation. The sensory profile of beers obtained with S38 or the brewer's yeasts did not show significant differences, thus suggesting that baker's strains of S. cerevisiae could represent a reservoir of biodiversity for the selection of starter strains for craft beer production.

Characterization of the volatile profiles of beer using headspace solid‐phase microextraction and gas chromatography–mass spectrometry

The objective of this study was a multivariate characterization of the volatile profile of beers. Such a characterization is timely considering the increasing worldwide consumption of beer, the continuous growth of microbreweries and the importance of volatile compounds to beer flavour. A method employing solid-phase microextraction and gas chromatography-mass spectrometry (SPME-GC-MS) was optimized and then applied to a sample set of 36 industrial and craft beers of various styles and fermentation types. The volatile profiles of different beer styles is described, with particular attention paid to the volatile compounds characteristic of a spontaneously fermented lambic raspberry framboise beer. Furthermore, it was also possible to identify which specific volatile compounds are principally responsible for the differences in the volatile profiles of top- and bottom-fermented beers. Moreover, a volatile fingerprint of the craft top-fermented Italian beers was defined, as they show a very similar volatile profile. Finally, the volatile compounds that are characteristic of the bock-style beers are described. The SPME-GC-MS analytical method optimized in this study is suitable for characterizing the volatile fingerprint of different beers, especially on the basis of the kind of fermentation (top, bottom or spontaneous), the method of production and the style of the beer.

How the Method of Beer Dispense Influences the Served CO2 Content and the Sensory Profile of Beer

The influence of the hopping method (boiling stage hopping or dry hopping), the fermentation temperature (12 and 18 °C), and the yeast strain (five different yeasts) on the physical-chemical characteristics (bitterness, color, alcohol content), the phenolic content, the volatile compounds, as well as the sensory profile of beers, has been studied. The hopping method was much more influential than temperature and yeast strain, however, its influence on volatile content clearly depended on the fermentation temperature, with a higher content of volatile compounds, when a higher fermentation temperature was employed. For phenolic compounds, dry hopping produced less polyphenol-rich beers, regardless of the fermentation temperature. Sensorily, it resulted in more floral and fruity beers than those produced by boiling stage hopping, which exhibited a more intense toasted aroma. Concerning yeast strain, no relationship could be established between the type of commercial yeast (bottom or top-fermenting) and the resulting volatile content.

The influence of different yeast strains Saccharomyces cerevisiae on aromatic profile of beers

The influence of different yeast strains Saccharomyces cerevisiae on aromatic profile of beers

Influence of Serial Repitching on Beer Polypeptide Profiles

The evolution of polypeptide profiles during three successive fermentations with yeast generation N0, N+1, and N+2 was examined under large scale brewing conditions using 1,000 and 3,000 hL cylindroconical vessels, coded as G and H, respectively. ANOVA analyses indicated that the total protein content decreased significantly from wort (before yeast pitching) to green beer (samples collected after 2, 4, 6, 8, and 10 days of fermentation), and in general increased from green beer to mature beer (collected during beer conditioning after 12 and 14 days of yeast addition). Polypeptides from wort, green beer, and mature beer (without further treatments) were separated by chromatography according to their molecular size and by RP-HPLC. Quantitative differences were observed in peak areas, indicating the polypeptide, peptide, and amino acid changes throughout the fermentation and conditioning processes due to foam formation, protein precipitation, and yeast metabolism. A MANOVA was performed using RP-HPLC profile of beer from N0, N+1, and N+2 yeast generations produced in G and H fermentation vessels to establish the effect of vessel size and yeast generation. F values indicated greater importance of the yeast generation than the vessel size on the beer polypeptide profile. Yeast generation effect was notable in generation N0. Beer produced with generations N+1 and N+2 in the two cylindroconical vessels gave similar polypeptide profiles.

How the Method of Beer Dispense Influences the Served CO2 Content and the Sensory Profile of Beer

The CO2 content of draught beer is usually considered to be a function of the original packaged beer CO2 content, the dispensing gas, and its pressure. This does not take into account one important parameter, which is the influence of the technique of beer dispense on the eventual CO2 content of beer in glass. The dispense of beer while minimizing foam creation, dispense in one draught, results in the beer in glass CO2 content being close to that of the original bottle or keg CO2 content of beer. For the tasters and lager beer in this study, such dispense technique results in higher carbonation flavor and also a more bitter taste, with more harsh bitterness character. Beer dispensed by one draught also emphasizes if the beer suffers from undesirable diacetyl off-flavor that was added in this study. In contrast, beer dispensed by a three-draught technique that has much in common with the legendary German “seven-minute-pils” provided beer that was considered to be superior in overall flavor. With the three-draught dispense technique, the first draught converted all the beer to foam on dispense, resulting in a substantial reduction in beer CO2 content. The subsequent two draughts also result in further CO2 loss, finally presenting a beer with a substantially lower CO2 content. Lager beer dispensed by this technique was superior in flavor in terms of finer bitterness character and intensity and less emphasis of diacetyl off flavor. A formula was developed to accurately predict the eventual beer CO2 content as a function of the amount of beer foam produced during dispense. These relationships are important not only for dispense recommendations to bartenders for optimal beer serving but also when preparing samples for degustation.

Optimization of a HS-SPME-GC-MS Procedure for Beer Volatile Profiling Using Response Surface Methodology: Application to Follow Aroma Stability of Beers Under Different Storage Conditions

The optimization of the main experimental variables, such as extraction temperature, volume of sample and the extraction time of an HS-SPME/GC-MS procedure, for profiling beer volatile analysis was evaluated using response surface methodology. A central composite circumscribed design was employed to study the effect of the experimental variables on the extraction of 28 representative volatile compounds of beer flavour profile. The parameters of the models were estimated by multiple linear regressions. The strongest influence in the volatile extraction yield was the volume of the sample (V) and the extraction temperature (T), with a positive and a negative effect, respectively. The performance characteristics of the optimised method were also determined, showing adequate linear ranges, repeatability, detection and quantification limits. The optimised methodology was applied to the same beer sample stored during 5 months at three different temperature conditions (4, 20 and 40 °C). Sampling was performed monthly, and the results showed that the concentration of most volatile compounds decreased during beer storage, although the rate of decrease was clearly higher at room temperature (20 °C) compared with refrigeration conditions (4 °C). Accelerated ageing conditions (40 °C) showed the most different volatile profile. Sensory analysis also revealed large differences in the overall quality of the samples, showing that even at room temperature the aroma profile of beer is greatly modified during its shelf life.

Sensory Characteristics of Romanian, Polish, Albanian and Former Yugoslavian Beers

In a multicultural market, attitudes towards the sensory quality of a beer can vary largely across ethnic groups. People are more likely to react positively to the sensory characteristics of beers that they are familiar with in their homeland market, than to the sensory qualities of beers brewed in the host country, considering that familiarity dictates to a large extent what is acceptable or not in the food domain. Further, beer sensory characteristics of migrants' native markets can differ largely from sensory qualities of beers brewed in the host country, since culture is a powerful trait d'union able to create distinctions across countries. This study evaluated the sensory profile of beers on sale in the Balkans and in Poland because of the relevance that these minorities have in Italy. Fifty-two beer samples were studied, partitioned into Romanian (n = 11), Albanian (n = 4), Polish (n = 7), former Yugoslavian (n = 21) and Italian (n = 9) according to Quantitative Descriptive Analysis. The results of this study revealed that Romanian beers were significantly (P < 0.001) more bitter, carbonated, alcoholic, and astringent than beers brewed in the other countries. Polish beers were the fullest-bodied and the richest in malty taste, while the former Yugoslavian beers were the fruitiest and most floral. Albanian brands were the richest in papery, worty, grainy, cooked vegetable-like and caramel-like taste. Hierarchical Cluster Analysis revealed that dominant brands of the Italian market were closer to the Polish and Yugoslavian beers than to the Romanian and Albanian.

Effect of Carbonyl Sulphide (COS), Ethyl Formate (EF) and Carbon Disulphide (CS2) on the Malting Quality of Barley and the Flavour Profile of Beer

New fumigants are needed to control grain insects because methyl bromide is being phased out as an ozone-depleting substance under the Montreal Protocol and because resistance to phosphine is increasing. Alternative fumigants also provide one strategy to manage resistance. To assess the effect of candidate fumigants on barley quality, malting and brewing trials were conducted with malting barley (Schooner), 9.4% moisture content, fumigated with carbonyl sulphide (COS), ethyl formate (EF) and carbon disulphide (CS2) at concentrations of 20, 90 and 36 mg/L respectively for 7 days at 20°C in riveted steel silos containing 33 t of barley. The appropriate industry body, the Malting and Brewing Industry Barley Technical Committee (MBIBTC) set the quality parameters to be evaluated and allocated work to the appropriate quality laboratories. Germination of fumigated barley was not affected by the fumigants. Residues of COS, EF and CS2 in outloading barley samples were 0.085 ± 0.0052, 0.4 ± 0.1 and 2.22 ± 0.07 mg/kg respectively, which were below the experimental permits of maximum residue levels (MRL). Residues of COS, EF and CS2 in malt, wort and beer were indistinguishable from those in unfumigated (or non-fumigated) barley. Ethyl formate and CS2 affected wort in increasing the apparent attenuation limit (AAL) and CS2 affected barley colour. Sulphur volatiles in the trial beer made from EF and CS2 (unlike COS) fumigated barley decreased significantly. Beer from COS, EF and CS2 fumigated barley had a somewhat higher 24-hour chill haze level (0.62–0.84) than beer from the untreated barley (0.53). The total alcohols and isoamyl acetate increased in beer made from EF fumigated barley. Carbonyl sulphide, EF and CS2, however, had no effect on beer flavour or quality.

Quantitative Sensomics Profiling of Hop-Derived Bitter Compounds Throughout a Full-Scale Beer Manufacturing Process

Although the complex taste profile of beer is well accepted to be reflected by the molecular blueprint of its sensometabolites, the knowledge available on the process-induced transformation of hop-derived phytochemicals into key sensometabolites during beer manufacturing is far from comprehensive. The objective of the present investigation was, therefore, to develop and apply a suitable HPLC-MS/MS method for the simultaneous and comprehensive quantitative monitoring of a total of 69 hop-derived sensometabolites in selected intermediary products throughout a full-scale beer manufacturing process. After data normalization, the individual sensometabolites were arranged into different clusters by means of agglomerative hierarchical analysis and visualized using a sensomics heatmap to verify the structure-specific reaction routes proposed for their formation during the beer brewing process.

Decrease of Aged Beer Aroma by the Reducing Activity of Brewing Yeast

The flavor profile of beer is subject to changes during storage. Since, possibly, yeast has an influence on flavor stability, the aim of this study was to examine if there is a direct impact of brewing yeast on aged aroma. This was achieved by refermentation of aged beers. It was shown that several aged aroma notes, such as cardboard, ribes, Maillard and Madeira, were removed almost entirely by brewing yeast, independently of the yeast or the beer type. This was explained by the reduction of aldehydes, mainly (E)-2-nonenal, Strecker aldehydes, 5-hydroxymethylfurfural and diacetyl, to their corresponding alcohols. Furthermore, it became evident that the reducing capacity of brewing yeast is high, but that yeast strain and compound specific residual concentrations remained in the refermented beer independently of the initial concentration. Finally, it appeared that aldehydes were not only reduced but also formed during refermentation.

Exploratory analysis of the volatile profile of beers by HS–SPME–GC

Kohonen Neural Network maps were used for exploratory analysis of Brazilian Pilsner beers. The input data consisted of the peak areas of the volatile profile compounds of samples obtained after headspace solid phase microextraction coupled to gas chromatography. The chromatographic peaks were identified as originating from compounds such as alcohols, esters, organic acids, phenolic compounds, ketone and others typically found in the headspace of such samples. Analysis of the Kohonen maps showed that the 20 different brands of beer could be grouped into six sets, with three of these sets having only one sample, according to the composition of their volatile fractions. The volatile species associated with the similarities and differences between each sample group were tentatively identified by mass spectrometry and their contributions to the grouping are discussed.

Retention of ochratoxin A and fumonisin B1 and B2 from beer on solid surfaces: comparison of efficiency of adsorbents with different origin

Fifteen solid materials with variable origin and various adsorption properties for retention of mycotoxins were tested—mineral materials, organic polymers and chemical modified silica gels that are used in widespread separation techniques. Some filtration materials currently utilized in brewing technology for beer clarifying and filtration were also examined. Adsorbents have been investigated in model and real samples (beer) and evaluated on the basis of adsorption capacity for ochratoxin A and fumonisin B1 and B2. Mentioned mycotoxins are commonly present in beers and may increase the risk on human health in high beer-consuming countries. The ability of adsorbent to retain mycotoxins on its surface was evaluated as micrograms of mycotoxin per one gram of adsorbent or as percentage of mycotoxin adsorbed. The experiments were accomplished in dynamic mode, which is mostly applied in beer production. The quality profile of beer after treatment with adsorbents in connection with high efficiency of mycotoxins’ removal was also considered. The main beer qualitative attributes such as pH value, color, iso-alpha acids were defined. As perspective adsorbents has shown to be carbon and modified silica gels. The retention of ochratoxin A on carbon was 90–96% in range of carbon dosages 2.5–6.5 g/l, and its retention on modified silica gels alters in scope of 64–94%. The retentive effect of fumonisin B1 and B2 on modified silica gels reached 74–100% in dependence on adsorbent dosage. Most changes underwent iso-alpha acids likely in consequence of retention on adsorbents together with mycotoxins. To achieve the scheduled goals the sensitive HPLC methods with fluorescence detection were used.

The alcohol acetyl transferase gene is a target of the cAMP/PKA and FGM nutrient-signalling pathways

The ATF1-encoded Saccharomyces cerevisiae yeast alcohol acetyl transferase I is responsible for the formation of several different volatile acetate esters during fermentations. A number of these volatile esters, e.g. ethyl acetate and isoamyl acetate, are amongst the most important aroma compounds in fermented beverages such as beer and wine. Manipulation of the expression levels of ATF1 in brewing yeast strains has a significant effect on the ester profile of beer. Northern blot analysis of ATF1 and its closely related homologue, Lg-ATF1, showed that these genes were rapidly induced by the addition of glucose to anaerobically grown carbon-starved cells. This induction was abolished in a protein kinase A (PKA)-attenuated strain, while a PKA-overactive strain showed stronger ATF1 expression, indicating that the Ras/cAMP/PKA signalling pathway is involved in this glucose induction. Furthermore, nitrogen was needed in the growth medium in order to maintain ATF1 expression. Long-term activation of ATF1 could also be obtained by the addition of the non-metabolisable amino acid homologue beta-L-alanine, showing that the effect of the nitrogen source did not depend on its metabolism. In addition to nutrient regulation, ATF1 and Lg-ATF1 expression levels were also affected by heat and ethanol stress. These findings help in the understanding of the effect of medium composition on volatile ester synthesis in industrial fermentations. In addition, the complex regulation provides new insights into the physiological role of Atf1p in yeast.

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.

STUDIES ON BEER HAZE FORMATION. II. DIMERIC FLAVANOIDS OBSERVED IN PROFILES OF BEER: NYLON 66 ADSORBATES

A peak in the gas chromatographic profile of beer: Nylon adsorbates has been found to comprise three unresolved biflavan components. One of these, molecular formula C30H26O12, consists of two C—C linked catechin units and has the same structure as a biflavan obtained by the acid catalysed interaction between cyanidiol and catechin. It appears to be the same as the procyanidin previously isolated from beer. The other components, both with molecular formula C30H26O13, have the same skeletal structure as the first, but are linked catechin-gallocatechin pairs, one being a prodelphinidin, the other a procyanidin. Dicatechin, a tannin obtained by treatment of catechin with dilute mineral acid, also seems likely to be a component of the adsorbate profiles.

RISK MANAGEMENT OF BEER FERMENTATION DIACETYL CONTROL

Diacetyl and 2, 3-pentandione are important contributors to beer flavor. These two compounds are grouped and reported as the vicinal diketone (VDK) content of beer. The removal of diacetyl is an important step in the maturation of beer. Diacetyl is formed by oxidative decarboxylation of ?-acetolactate. In the next step of fermentation, diacetyl is transformed to acetoin by enzymatic complex of the yeast. For flavor profile of beer it is very important that the concentration of VDK to be less than flavor threshold. In brewery pilot plant from USAMV Cluj-Napoca production trials were performed to monitoring any influence on beer quality and to optimize saving in time and cost.