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Upon beer storage, the levels of staling aldehydes increase, which coincides with the appearance of characteristic off-flavors. Bound-state aldehydes have been reported as potential sources of off-...

As a continuation of our previous work, which concerned the binding of aldehydes to bisulfite and cysteine, this article presents more results on the applicability of 4-vinylpyridine addition to beer prior to analysis aiming at release of aldehydes from these preformed bound states, thus making them quantifiable with the headspace solid-phase microextraction method combined with gas chromatography-mass spectrometry. This article also presents the first results on spiking beer samples with cysteine prior to forced-aging, pointing to the important role of cysteine in beer flavor stability. Both the levels in free and bound aldehydes show a relatively large degree of variation among different beers, but also between marker aldehydes. For some aldehydes (e.g., hexanal), the bound amount was shown to increase rather strongly upon forced beer aging, whereas for others (e.g., 2-methylpropanal), large amounts appeared to already be present in a bound state in the fresh samples. Spiking beer samples with cysteine prior to aging significantly lowered the aldehyde levels compared with nonspiked samples. Flavor stability of the cysteine-spiked beers was thereby greatly improved through aldehyde-cysteine adduct formation. It was further hypothesized that, in addition to efficient binding of aldehydes, cysteine also inhibits the formation of furfural during beer aging from Maillard reaction intermediates.

Traditional sour beers are produced by spontaneous fermentations involving numerous yeast and bacterial species. One of the traits that separates sour beers from ales and lagers is the high concentration of organic acids such as lactic acid and acetic acid, which results in reduced pH and increased acidic taste. Several challenges complicate the production of sour beers through traditional methods. These include poor process control, lack of consistency in product quality, and lengthy fermentation times. This review summarizes the methods for traditional sour beer production with a focus on the use of lactobacilli to generate this beverage. In addition, the review describes the use of selected pure cultures of microorganisms with desirable properties in conjunction with careful application of processing steps. Together, this facilitates the production of sour beer with a higher level of process control and more rapid fermentation compared to traditional methods.

The preference and drinkability of fresh beer compared with aged beer was tested using a 'paired comparison test'. After a duo test with small samples, respondents could freely consume the beer of their choice. The results show that the initial preference for fresh beer was significantly higher than the preference for aged beer, with 65% of respondents taking fresh beer first after the duo test. The drinkability of fresh beer also scored significantly higher, with 35% more fresh beer consumed. However, since multiple respondents consecutively consumed multiple aged beers, it cannot be concluded that aged beer results in a lower consumption volume (per capita) when compared with fresh beer. Additionally, Belgians older than 24 years particularly favoured and consumed the fresh beer in the experiment. This was attributed to the influencing and mimicking behaviour of the other respondent groups, since the table setting and table sizes were also found to be important parameters. In this paper, we show the continuing importance of research into beer flavour stability. (C) 2019 The Institute of Brewing & Distilling

Increasing popularity of sour beer urges the development of novel solutions for controlled fermentations both for fast acidification and consistency in product flavor and quality. One possible approach is the use of Saccharomyces cerevisiae in co-fermentation with Lactobacillus species, which produce lactic acid as a major end-product of carbohydrate catabolism. The ability of lactobacilli to ferment beer is determined by their capacity to sustain brewing-related stresses, including hop iso-α acids, low pH and ethanol. Here, we evaluated the tolerance of Lactobacillus brevis BSO464 and Lactobacillus buchneri CD034 to beer conditions and different fermentation strategies as well as their use in the brewing process in mixed fermentation with a brewer's yeast, S. cerevisiae US-05. Results were compared with those obtained with a commercial Lactobacillus plantarum (WildBrewTM Sour Pitch), a strain commonly used for kettle souring. In pure cultures, the three strains showed varying susceptibility to stresses, with L. brevis being the most resistant and L. plantarum displaying the lowest stress tolerance. When in co-fermentation with S. cerevisiae, both L. plantarum and L. brevis were able to generate sour beer in as little as 21 days, and their presence positively influenced the composition of flavor-active compounds. Both sour beers were sensorially different from each other and from a reference beer fermented by S. cerevisiae alone. While the beer produced with L. plantarum had an increased intensity in fruity odor and dried fruit odor, the L. brevis beer had a higher total flavor intensity, acidic taste and astringency. Remarkably, the beer generated with L. brevis was perceived as comparable to a commercial sour beer in multiple sensory attributes. Taken together, this study demonstrates the feasibility of using L. brevis BSO464 and L. plantarum in co-fermentation with S. cerevisiae for controlled sour beer production with shortened production time. ispartof: Frontiers In Microbiology vol:11 ispartof: location:Switzerland status: Published online

Brewing using enzyme rich ‘green’ (germinated, but not kilned) malt has the potential to unlock considerable energy savings in the malting and brewing chain. This paper examines the major quality issues associated with green malt, by monitoring lipoxygenase (LOX) activity and S‐methyl methionine (SMM) levels through a micromalting cycle both with and without rootlets after 48 h of germination. The data suggest that rootlets are a major concern when brewing with green malt and that their influence on wort and beer quality needs to be further investigated. Lipoxygenase activity and nonenal potential were measured following treatment under varying conditions of pH, temperature and pre‐treatment. Results indicated that lipoxygenase activity can be controlled to a substantial degree by manipulating these limiting factors, while preserving diastatic enzyme activity. Green malt worts were then prepared from (i) whole green malt immediately post‐germination; (ii) heat treated green malt (65°C x 1 h); (iii) re‐steeped green malt and (iv) endosperm‐rich extracts of green malt after the husk and rootlets had been removed; using laboratory mashing with a ‘LOX‐hostile’ mash schedule. Data were compared with mashing of kilned pale malt made from the same green malt, as a reference point. Based on the present data, re‐steeping of green malt in combination with a LOX hostile mashing environment (63°C, pH 5.2) could help to control LOX activity and the trans‐2‐nonenal potential of green malt. The resultant brewing process would need to be optimised to deal with the elevated SMM levels in green malt worts. © 2020 The Authors. Journal of the Institute of Brewing published by John Wiley & Sons Ltd on behalf of The Institute of Brewing & Distilling

et al., Global insights into cellular organization and genome function require comprehensive understanding of the interactome networks that mediate genotype–phenotype relationships1,2. Here we present a human ‘all-by-all’ reference interactome map of human binary protein interactions, or ‘HuRI’. With approximately 53,000 protein–protein interactions, HuRI has approximately four times as many such interactions as there are high-quality curated interactions from small-scale studies. The integration of HuRI with genome3, transcriptome4 and proteome5 data enables cellular function to be studied within most physiological or pathological cellular contexts. We demonstrate the utility of HuRI in identifying the specific subcellular roles of protein–protein interactions. Inferred tissue-specific networks reveal general principles for the formation of cellular context-specific functions and elucidate potential molecular mechanisms that might underlie tissue-specific phenotypes of Mendelian diseases. HuRI is a systematic proteome-wide reference that links genomic variation to phenotypic outcomes., This work was primarily supported by the National Institutes of Health (NIH) National Human Genome Research Institute (NHGRI) grant U41HG001715 (M.V., F.P.R., D.E.H., M.A.C., G.D.B. and J.T.) with additional support from NIH grants P50HG004233 (M.V. and F.P.R.), U01HL098166 (M.V.), U01HG007690 (M.V.), R01GM109199 (M.A.C.), Canadian Institute for Health Research (CIHR) Foundation Grants (F.P.R. and J. Rak), the Canada Excellence Research Chairs Program (F.P.R.) and an American Heart Association grant 15CVGPS23430000 (M.V.). D.-K.K. was supported by a Banting Postdoctoral Fellowship through the Natural Sciences and Engineering Research Council (NSERC) of Canada and by the Basic Science Research Program through the National Research Foundation (NRF) of Korea funded by the Ministry of Education (2017R1A6A3A03004385). C. Pons was supported by a Ramon Cajal fellowship (RYC-2017-22959). G.M.S. was supported by NIH Training Grant T32CA009361. M.V. is a Chercheurv Qualifié Honoraire from the Fonds de la Recherche Scientifique (FRS-FNRS, Wallonia-Brussels Federation, Belgium).

Yeasts may play a unique role in heavily hopped beers from different perspectives. To evaluate the impact of different yeast strains, two types of trials at pilot scale were performed: one with a New England IPA type beer and another with a brut IPA type beer. In both trials, POF+ yeast strains produced higher amounts of phenolic flavors, which were perceived by the trained assessors. Along with it, a reduced overall intensity perception of the entire hop expression was noticed. The high dosage of fruity hops added in later stages in these IPA beer types is not enough to cover the perception of phenolic flavors, even when below the threshold level. ispartof: Master Brewers Association of the Americas vol:56 issue:4 pages:124-126 status: published

Currently, there is a strong interest in sour beers, with more breweries producing sour styles and sales continuing to increase. There are many different ways for producing sour beer, offering breweries a variety of opportunities to pursue new beverages and diversify their portfolio. These methods range from modern kettle souring and short term mixed fermentation to traditional long term mixed fermentation and maturation in wooden barrels. While the first methods enable quick souring, these beers generally lack the flavour complexity that can be obtained through more traditional methods. Here, we discuss the microbiology of sour beers and review the most common production methods as well as the most important beer styles that are produced using these methods. Further, we report a number of novel methods that have the potential to produce the next generation of flavour-rich sour beers. Increased knowledge on the microbiology and flavour development in traditional sours will help developing such next generation of sour beers. ispartof: BrewingScience vol:72 issue:3-4 pages:78-88 status: published

Global insights into cellular organization and function require comprehensive understanding of interactome networks. Similar to how a reference genome sequence revolutionized human genetics, a reference map of the human interactome network is critical to fully understand genotype-phenotype relationships. Here we present the first human “all-by-all” binary reference interactome map, or “HuRI”. With ~53,000 high-quality protein-protein interactions (PPIs), HuRI is approximately four times larger than the information curated from small-scale studies available in the literature. Integrating HuRI with genome, transcriptome and proteome data enables the study of cellular function within essentially any physiological or pathological cellular context. We demonstrate the use of HuRI in identifying specific subcellular roles of PPIs and protein function modulation via splicing during brain development. Inferred tissue-specific networks reveal general principles for the formation of cellular context-specific functions and elucidate potential molecular mechanisms underlying tissue-specific phenotypes of Mendelian diseases. HuRI thus represents an unprecedented, systematic reference linking genomic variation to phenotypic outcomes.

Objectives: A critical and uniform assessment of mucosal scarring following oral surgery is needed to refine surgical decision-making. For that purpose, the Mucosal Scarring Index (MSI) was developed. Materials and methods: The MSI is a composite index based on five parameters: width, height/contour, color, suture marks, and overall appearance. Each parameter is assessed with a 0–1–2 score, yielding a MSI score ranging from 0 (no scar) to 10 (most extreme scar). Five periodontists, 5 prosthodontists, and 5 orthodontists assessed scarring using the new index on the basis of 30 clinical photographs of post-surgical sites. Cases had been carefully selected making sure that the complete spectrum of the index would be represented in the analysis. Duplicate evaluation was performed with a 2-h interval and in random order of cases. Results: On a total of 450 assessments, the mean MSI amounted to 4.91 (SD 3.087) with no significant differences between scores given by periodontists (mean 4.65; SD 3.054), orthodontists(mean 5.04; SD 3.301), or prosthodontists (mean 4.81; SD 2.842) (p = 0.548). The MSI appeared a highly reliable index given excellent inter- as well as intra-examiner agreement (ICC > 0.9; p < 0.001). Clinicians agreed most on ‘overall appearance’ (kappa = 0.582; p < 0.001) and least on ‘suture marks’ (kappa = 0.352; p < 0.001). Conclusion: The MSI is an effective, easy-to-use, and reliable composite index to assess mucosal scarring following oral surgical procedures. Clinical relevance: The MSI can be used as an adjunct to other indices in the esthetic evaluation of oral surgical procedures.

The reliability and validity of psychiatric diagnoses have always been a major concern. The Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) reliability field trials yielded ambiguous results, with some diagnostic categories scoring well below par. We argue that the emphasis on the reliability of psychiatric diagnoses, which has dominated psychiatric nosology and guided the endeavor of improving the DSM in its consecutive editions, is misguided and lacks in structural validity. In this article, we defend a pragmatic view on psychiatric disease as the most fruitful approach to an understanding of what the categorical distinctions in the DSM (can) represent. Disorders in the DSM are descriptions of clinical pictures and do not necessarily correspond to an identified pathological substrate. Although this is a logical result of the nature of psychiatric disease, it bears important consequences. The various DSM disease categories are not uniform but should be regarded as representing different kinds of disorders, ranging from a separation from normal behavior based on practical grounds to the discrete kind of disorders envisioned by proponents of a strong realistic view. We argue that the explication of kinds of disorders outlined in this article provides interesting perspectives on the problems of reliability and validity that the DSM faces.

This paper describes the method validation for the simultaneous determination of seven cysteinylated aldehydes, i.e. 2-substituted 1,3-thiazolidines-4-carboxylic acids, using ultra-high-performance liquid chromatography-mass spectrometry (UHPLC–MS). Authentic reference compounds were first synthesized for identification and quantification purposes. Moreover, nuclear magnetic resonance (1H NMR and 13C NMR) was applied for verification of their structure, while ultra-high-performance liquid chromatography–mass spectrometry (UHPLC–MS) was applied for estimation of the purity. The method for quantification of cysteinylated aldehydes in model solutions has been validated according to the criteria and procedures described in international standards. The synthesized compounds were successfully identified via UHPLC–MS by comparing retention time and MS spectra with the commercial reference compounds. Method validation revealed good linearity (R2 > 0.995) over the range of 0.4–2.2 µg/L to approximately 1000 µg/L, depending on the analyte. The limits of quantification varied from 0.9 to 4.3 µg/L depending on the nature of the compound. Furthermore, evaluation of the method showed good accuracy and stability of the standard solutions. Reported chromatographic recoveries ranged from 112 to 120%. Consequently, the currently described method was applied on malt and beer samples. For the first time, quantification of cysteinylated aldehydes was obtained in malt. In contrast, in fresh beers unambiguous identification of these compounds was not achieved.

Overall ageing scores (OAS) are used by expert beer tasters to distinguish between the different aromas and tastes, in order to assess the sensorial quality and flavour stability of beer. Flavour instability is an important issue to brewers owing to the increased global demand for beer and the difficulties of controlling beer quality in remote locations when exported. In this paper, the idea was developed and a model constructed that is able to estimate the OAS as a function of temperature and time. The study highlights not only the exponential impact of temperature on lager quality, but also the importance of the time of exposure (nonlinear effect). Further, a hypothetical case study was performed in which the OAS was determined of a lager exposed to the temperature conditions in an important Belgian beer importmarket. The results indicate that in cities with amild climate (e.g. UK and Germany), lager beer will suffer quality degradation to a limited extent. Temperature in warm climate cities (e.g. Italy and China) will significantly reduce the shelf-life of lager beer in a short time frame, stressing the importance of flavour quality and stability. The model can be used in both industry and research when developing commercial decisions.

Breweries are exporting their brands overseas, resulting in an increasingly competitive and globalised beer market. Inevitably, the beer experiences varying and prolonged periods of transport and storage prior to consumption. During this process, the flavour of fresh beer deteriorates, leading to the presence of stale flavours and a decrease in the drinkability of the beer. Results reported here show that an increased temperature during beer transport and storage causes significant flavour deterioration, as determined analytically (increase in aldehydes, beer colour and haze formation, decrease in iso‐α‐acids concentration) and sensorially (increase in overall aging score). Further, laboratory experiments show that the vibration of beer results in a rapid decrease of oxygen. Moreover, inappropriate storage temperature has a negative effect on beer quality and stability, in particular when combined with vibration.

BACKGROUND Beer flavor stability is important to brewers as a result of the increased global demand for beer. Increasing export leads to prolonged periods of transportation and storage and causes fresh flavor deterioration. Therefore, the present study examined the effect of different temperatures in combination with vibrations on beer quality. Beer was exposed to vibrations (50 Hz, 15 m s−2, simulating transport) at 5, 30 and 45 °C for 22, 38 and 90 h and (for half the samples) aged for 60 days at 30 °C. RESULTS The results obtained indicated decreased oxygen concentrations as a result of an elevated temperature and vibrations. There was no effect (P > 0.05) on color and a limited effect of temperature and vibrations on iso‐α‐acids. The parameters temperature and vibrations have a significant influence (P < 0.05) on aldehyde concentrations, namely total aldehydes, and especially 2‐methylpropanal, 2‐methylbutanal and furfural. CONCLUSION The impact of vibrations on the aldehydes concentrations was substantial when subjected to an elevated temperature. Furthermore, a forced aging test of shorter duration than traditional methods might be developed.