Composition Of Beer Research Articles

Formation of Flavor-Active Compounds during Continuous Alcohol-Free Beer Production: The Influence of Yeast Strain, Reactor Configuration, and Carrier Type

The aim of this study is to demonstrate the influence of production strains (bottom-fermenting Saccharomyces pastorianus and S. cerevisiae with disruption in the KGD2 gene), carrier materials (spent grains and corncobs), reactor arrangements (packed-bed and gas-lift reactors), and mixing regimes (ideally mixed and plug flow) on the formation of flavor-active compounds during alcohol-free beer production. In addition, the composition of alcohol-free beer produced on a laboratory scale was compared with those of commercial products. The results confirmed the influence of each component of the production system (yeast strain, reactor, and carrier) on flavor formation, but their individual importance was case specific. The results indicate that the interplay between the appropriate production strain, carrier material, and bioreactor design is very important in continuous immobilized cell reactors and that suitable combinations could be used to improve both system performance and product quality.

Evaluation of beer deterioration by gas chromatography–mass spectrometry/multivariate analysis: A rapid tool for assessing beer composition

Beer stability is a major concern for the brewing industry, as beer characteristics may be subject to significant changes during storage. This paper describes a novel non-targeted methodology for monitoring the chemical changes occurring in a lager beer exposed to accelerated aging (induced by thermal treatment: 18 days at 45°C), using gas chromatography–mass spectrometry in tandem with multivariate analysis (GC–MS/MVA). Optimization of the chromatographic run was performed, achieving a threefold reduction of the chromatographic time. Although losing optimum resolution, rapid GC runs showed similar chromatographic profiles and semi-quantitative ability to characterize volatile compounds. To evaluate the variations on the global volatile signature (chromatographic profile and m/z pattern of fragmentation in each scan) of beer during thermal deterioration, a non-supervised multivariate analysis method, Principal Component Analysis (PCA), was applied to the GC–MS data. This methodology allowed not only the rapid identification of the degree of deterioration affecting beer, but also the identification of specific compounds of relevance to the thermal deterioration process of beer, both well established markers such as 5-hydroxymethylfufural (5-HMF), furfural and diethyl succinate, as well as other compounds, to our knowledge, newly correlated to beer aging.

Relationship between Matrix Foaming Potential, Beer Composition, and Foam Stability

Qualitative research with Czech beer customers was the starting point for this investigation of beer foam quality. We observed that customers start to pay attention to foam no earlier than when “bald patches” begin to appear on the surface of the beer. This foam stability trait was observed toward the end of foam collapse. In contrast, foam stability measured by common quality control methods such as NIBEM conventionally measure foam stability during the first stages of foam collapse. To evaluate the rate of appearance of bald patches on beer, we have developed a method that predicts foam stability during the later stages of collapse, in order to reflect Czech customers' expectations for foam quality. This alternative foam analysis method directly produces foam from degassed beer and evaluates its quality to determine the matrix foaming potential measurement. Foam stability is a compromise between foam-positive and -negative beer components. Traditionally accepted foam components such as foam-positive proteins and hop iso-α-acids describe the quality of foam only to a limited extent, particularly because iso-α-acids content is tightly controlled within brands. Our foam analysis technique indicates that beer is essentially saturated with more than sufficient levels of foam-positive components to satisfy the requirements for foam generation and stability. Consequently, we demonstrate that foam-negative components are the actual problem that needs to be solved to improve foam quality with respect to the appearance of bald patches on the surface of beer.

Structure, Organoleptic Properties, Quantification Methods, and Stability of Phenolic Compounds in Beer—A Review

Beer composition changes through storage, altering the quality of the product. In the past decade, many papers have been devoted to the compounds responsible for aged-beer off-flavors, mainly trans-2-nonenal, methional, and dimethyltrisulfide. Due to their huge antioxidant activity, polyphenols have often been described as key compounds for limiting beer staling. Yet phenolic structures also evolve through storage. Low-molecular-weight phenols like 4-vinylsyringol can impart off-flavors in aged beer, whilst flavonoids strongly influence astringency, haze, and color. The instability of stilbenes, prenylchalcones, and derived flavanones could also modify their health potential through storage. After reviewing the structures and properties of all phenolic compounds found in beer, this paper will try to assess the impact of their degradation through aging. Extraction procedures for their quantification and treatments for their removal are also described.

Technological Steps and Yeast Biomass as Factors Affecting the Lipid Content of Beer during the Brewing Process

Knowledge of lipid content and composition in the brewing process enables the quality control of the final product. Lipids have a beneficial effect on yeast growth during fermentation as well as deleterious effects on end-product quality. The lipid content of a beer affects its ability to form a stable head of foam and plays an important role in beer staling. Lipid oxidation during wort production is of great interest because of its effect on beer quality: both lipids and their oxidation products are known to have adverse effects on beer flavor, whereas interactions between lipids and protein films stabilizing the gas bubbles are thought to cause the collapse of foam. In this background, the aim of this research was the characterization of the lipid content during a brewing process for evaluating the influence of both technological steps and yeast biomass in the lipid composition of beer. Lipid contents and their fatty acid profile were evaluated in brewing raw materials, wort, and beer. A high-resolution gas chromatography-flame ionization detector (HRGC-FID) system was used for fatty acid determination in lipid extracts. The results of the present study highlighted that the main technological steps influencing the lipid content in brewing byproduct and beer were clarification in a whirlpool and filtration. Moreover, the presence of metabolically active yeast cells (used as starter culture) were found to have a great influence on the fatty acids composition of lipids.

A Chemometrics Approach for Distinguishing between Beers Using near Infrared Spectroscopy

Thirty-eight beers from different producing areas and/or makers were distinguished by principal component analysis (PCA) of the near infrared (NIR) spectra acquired by a portable NIR spectrometer. Classsification of Akita beers: beers locally produced in Akita prefecture, Japan, from other famous brand beers could be successfully performed, especially when the PCA was calculated on the standard normal variate (SNV) spectra. The classification equations use information related to water and CH2absorption that reflected the differences in chemical com position of beers due to different production processes. In addition, the compositions of total polyphenol and total nitrogen were estimated from NIR spectra by multiple linear regression (MLR). This study showed that NIR spectroscopy is promising for beer quality evaluation, both for identifying multifarious beers including Akita beers using PCA and for rapid in-line quality control and inspection for beer production using the quantitative MLR analysis.

Fatty Acids Composition Differences Between Beers Made with All-Malt and Brewer's Corn Grits and Malt

Barley is the main raw material used for beer production, but it must first be converted into malt before it can be used in brewing. Unmalted cereals, such as corn, rice, wheat, and sorghum, are often used as adjuncts. Corn products (which contain a more cost-effective form of carbohydrate) are traditionally used as adjuncts in the United States and Europe because they provide extract at a lower cost than can be obtained using malted barley. Corn adjuncts are readily available and provide other positive effects as well, such as color adjustment, fuller flavor, etc. The addition of corn products as raw materials in an all-malt beer recipe is considered an adulteration of the beer. The aim of this research was to evaluate the fatty acids composition of beer as a method of ascertaining the presence of corn grits used as an adjunct and to determine if its presence can be verified in labeled all-malt beers. A correlation between the different fatty acids compositions of beers with and without corn grits could be an index to evaluate the presence of solid corn adjunct in beer. The lipids contents and fatty acids profiles were evaluated for malt and corn, labeled all-malt beer, and labeled beer with added corn grits. The results obtained in this preliminary study showed a potential correlation between the fatty acids compositions of beer lipids and those of different raw materials used in a recipe.

The wars of the carbohydrates 7. Does consuming carbohydrate slowly elicit a lower spike in blood glucose?

The wars of the carbohydrates 7. Does consuming carbohydrate slowly elicit a lower spike in blood glucose?

Composition of Beer by 1H NMR Spectroscopy: Effects of Brewing Site and Date of Production

A principal component analysis (PCA) of 1H NMR spectra of beers differing in production site (A, B, C) and date is described, to obtain information about composition variability. First, lactic and pyruvic acids contents were found to vary significantly between production sites, good reproducibility between dates being found for site A but not for sites B and C beers. Second, site B beers were clearly distinguished by the predominance of linear dextrins, while A and C beers were richer in branched dextrins. Carbohydrate reproducibility between dates is poorer for site C with dextrin branching degree varying significantly. Finally, all production sites were successfully distinguished by their contents in adenosine/inosine, uridine, tyrosine/tyrosol, and 2-phenylethanol, reproducibility between dates being again poorer for site C. Interpretation of the above compositional differences is discussed in terms of the biochemistry taking place during brewing, and possible applications of the method in brewing process control are envisaged.

Application of NMR spectroscopy and LC-NMR/MS to the identification of carbohydrates in beer.

The application of LC-NMR/MS for the direct identification of carbohydrates in beer has been studied. Carbohydrates are major beer components, and their structural characterization by NMR alone is seriously hindered by strong spectroscopic overlap. Direct analysis of beer by LC-NMR/MS enables the rapid (1-2 h) identification of dextrins with degree of polymerization (DP) of up to nine monomers, with degassing being the only sample treatment required. Although the presence of alpha(1-->6) branching points is easily indicated by NMR for each subfraction separated by LC, difficulties arise for the unambiguous assignment of linear or branched forms of high DP dextrins. The two beer samples investigated in this work were found to have significantly different oligosaccharide compositions, reflecting the different production conditions employed. The use of hyphenated NMR for the rapid characterization of the carbohydrate composition of beers may be the basis of a useful tool for the quality control of beer.

Characterization of the aromatic composition of some liquid foods by nuclear magnetic resonance spectrometry and liquid chromatography with nuclear magnetic resonance and mass spectrometric detection

This paper describes the first application of NMR spectroscopy and LC-NMR/MS to the direct analysis of the aromatic composition of beer, grape juice and a wine phenolic extract. 1 H NMR spectroscopy provides non-invasive information on the overall aromatic profile and enables the identification of some compounds. However, a more comprehensive assignment is hindered by the low peak intensity and strong signal overlap in the low-field spectral region, as well as by the inherent lack of scalar coupling information for many aromatic compounds present. LC-NMR/MS can overcome these problems and is shown to aid significantly in the identification of aromatic compounds composing all samples analyzed. Some examples are the identification of several cinnamic acids (e.g. p-coumaric, trans-coutaric and trans-caftaric) in grape juice, the identification of 2-phenylethanol, tyrosol and tryptophol in beer and the detection of phenolics such as catechin, epicatechin, trans-resveratrol, tyrosol and caffeic acid in the wine extract.

Yeast cells, beer composition and mean pore diameter impacts on fouling and retention during cross-flow filtration of beer with ceramic membranes

Clarification of rough beer (RB) and pasteurisation of clarified beer (CB) by cross-flow microfiltration (CFMF) stand as potential applications of membranes in the food industry. This study is based on the comparison of the resistances to mass transfer obtained during the filtration of RB and CB. Empirical correlations made it possible to calculate the CB resistances for the same conditions of transmembrane pressure and cross-flow velocity as for the RB filtration runs. The 1.4 μm membrane led to much lower resistances than the other membranes because of the lower retention rates of the beer compounds such as proteins and polyphenols. In this case, the predominant fouling mechanism was due to the yeast cell layer which was very sensitive to cross-flow velocity. On the other hand, with the 0.1, 0.45 and 0.8 μm membranes, the retention or adsorption of the CB compounds, such as proteins and polyphenols was the predominant mechanism. The resistances obtained with the rough and CB were fairly similar. We assume that the presence of yeast cells lead to less compact proteins and polyphenols fouling.

Proteins and amino acids in beers, their contents and relationships with other analytical data

Fluorometry, ion-exchange chromatography, electrophoretic separations and Fourier transform–infrared (FT–IR) spectra were used to determine and characterize amino acids and proteins in 15 different beer samples. Proteins precipitated by ammonium sulfate yielded complex electrophoretic patterns. The major bands corresponded to 45–40 kDa as determined by a two-dimensional gel electrophoresis (2-DE). Proteins and some amino acids are partially responsible for nutritional value and stability of beer. Therefore, electrophoretic analysis revealed that protein characterization of beer during all technological stages might be useful in its quality. FT–IR protein spectra showed the presence of I, II and III amide bands. Protein distribution and amino acid composition of beer differ significantly, depending on the raw materials and enzymatic reactions used in beer technology. Concentrations of histamine (3.02–3.23 mg/l), proline (1.60–3.13 mg/l) and tyramine (3.61–7.4 mg/l) increased during beer fermentation. Statistically significant change was registered in the protein content of the final product, which was less than that in wort ( p<0.005). Levels of tyramine and proline, which were higher than in wort ( p<0.025) showed significant changes. This investigation shows that, in Israeli, Mexican and Brazilian beers, the contents of protein and amino acids are in accordance with the international standards.

Prediction of the Formation of Frozen Beer Precipitates

The presence of frozen beer precipitates in packaged beer is a major consumer complaint, especially during cold winters. Therefore, it is important for brewers to predict the frozen stability of finished beer. The frozen stability of a packaged beer cannot be predicted by methods used to predict colloidal stability, such as the forcing test or alcohol-chilling test. To evaluate the frozen stability of canned beer, the freeze and thaw (F&T) cycle test was developed. We reproduced the change in outdoor temperature over 24 hr, which ranged from −2 to −12°C during winter, in a programmable incubator and measured the amount of precipitates formed. There was a large variation in the amount of frozen beer precipitates (F&T values) formed in commercial beers. Using this test, we found that two factors affect the frozen stability of beer. One factor is the composition of beer. The F&T value usually increased with an increase in the β-glucan content of beer. However, beer components such as α-glucan also greatly affected frozen stability. The other major factor affecting frozen stability is the practical freezing point of a packaged beer, which ranged from −7.1 to 13.8°C. We can determine the frozen stability of beer from these two factors and improve the visual quality of beer.

Beer: tap into the art and science of brewing

Beer: Tap into the Art and Science of Brewing is the first book that enables the nonspecialist to understand this science and technology. Charles Bamforth, an esteemed authority on brewing science, has written a witty and easy-to-understand volume that covers everything from the basis of selection of the best barley, hops, and yeast through to the composition of beer as it affects the taste, head, and wholesomeness of the finished drink. Set against a historical background, Bamforth traces the history of beer from ancient Babylon to today's sophisticated brewing centers, with forecasts of what the brewing industry will look like in the twenty-first century. Beer: Tap into the Art and Science of Brewing is an excellent introduction for those interested in the brewing business, including entrepreneurs entering the expanding world of micro- and boutique brewing, by a recognized authority within the industry. This book will appeal not only to those whose involvement in beer is restricted to its consumption but also to those with an interest in science who will appreciate the fascinating manner by which the chemistry and microbiology of brewing have been unraveled by scientists. It is also a fun and informative book that will satiate the thirst of all beer enthusiasts.

Em virtude da progressiva substituição dos adjuntos amiláceos pelos xaropes com alta concentração de maltose nas cervejarias brasileiras, o presente trabalho teve por objetivo comparar hidrolisados de milho e de mandioca, como adjunto de malte, na fabricação de cerveja tipo Pilsen, em escala de laboratório. Os hidrolisados foram produzidos a partir de amido de milho e fécula de mandioca, sendo que na liqüefação e sacarificação da fração amilácea destes produtos foram utilizadas, respectivamente, as enzimas comerciais Termamil (alfa amilase bacteriana) e Fungamil (alfa amilase fúngica). Na fabricação das cervejas, a proporção de malte e hidrolisado foi de 2 para 1, na base do extrato. O mosto foi produzido pelo processo de infusão e após resfriamento e clarificação foi inoculado com levedura cervejeira de baixa fermentação. A fermentação transcorreu a 10 °C até 90% de atenuação do extrato aparente fermentável. As cervejas foram engarrafadas e, em seguida, maturadas a 0 °C, por 14 dias. Terminado o processo de fabricação, as cervejas foram analisadas química e sensorialmente. A semelhança na composição química dos hidrolisados de milho e de mandioca refletiu na composição química dos mostos e das cervejas. Não houve diferença estatística entre os mostos e entre as cervejas testadas para todos os parâmetros químicos analisados. Também, não existiu diferença sensorial entre as cervejas produzidas com hidrolisado de milho e hidrolisado de mandioca. Concluiu-se que a fécula de mandioca apresenta potencial de uso como matéria prima para a fabricação de xarope de maltose de uso cervejeiro e que há elevada probabilidade de sucesso no uso desse xarope para a fabricação de cervejas.

Protein composition of beer as revealed by high-resolution two-dimensional electrophoresis

The first page of this article is displayed as the abstract.

Influence of absolute pressure on mass transfer kinetics in beer dialysis

Using experimental results of chemical composition of initial beer, dialysed beer and dialysate, obtained in laboratory scale equipment for dialysis, basic parameters for mass transfer kinetics were determined. It was found that absolute pressure in the system under the medium flow rate of 300 ml/min increased alcohol separate selectivity. As the result of the specific two-phase character of beer, the working pressure in the system for beer dialysis did not fall below 3–4 bar.

Effect of Hopping on the Headspace Volatile Composition of Beer

The effects of hop variety on the beer volatile constituents resulting from kettle hopping were studied. Three specially brewed beers, each hopped with single varieties of hops (Hallertau, Galena, ...

Chemical studies on sekete beer

The chemical composition of sekete beer and the maize used in its preparation are reported. Apart from calcium, decreases in the values of phosphorus, magnesium, potassium and sodium were observed in the beer. Riboflavin and niacin contents increased at the end of fermentation while thiamine decreased slightly. An increase in the moisture, nitrogen and protein contents is reported. The ash and crude fibre contents, however, decreased.