Content In Beer Research Articles

Development and validation of a liquid chromatography tandem mass spectrometry method for the determination of 10 mycotoxins in beer of the Chinese market and exposure estimate

Mycotoxins are important risk factors in beer. In this study, a liquid chromatography tandem mass spectrometry (LC-MS/MS) method was developed to determine 10 mycotoxins in beer within 6 min. The method is fast, efficient, and has a simple and quick sample preparation. Validation was conducted based on the performance standards specified in Commission Decision 657/2002/EC, and the results demonstrated excellent linearity (R2 > 0.99), repeatability (RSD < 5 %), quantification limits (0.005–20.246 µg/L), and recovery rates (77 %–118 %). The prevalence of the 10 mycotoxins in 96 beers purchased from the Chinese market was analyzed, and the exposure of the Chinese population to mycotoxins through beer consumption was assessed. Deoxynivalenol (DON) was detected in 93.75 % of the beers, and the incidence of fumonisins (FBs) and zearalenone (ZEN) exceeded 50 %. Beer intake contributed significantly to the exposure of aflatoxins (AFs) and DON, especially in males. Correlation analysis between mycotoxin content in beer, raw materials, and the brewing process revealed that the brewing process significantly affected the content of DON (P < 0.001), while auxiliary materials also had a significant impact on the content of FBs and DON (P < 0.001). This study holds great significance in producing higher quality and safer beer.

Production of the prolyl endoprotease (PEP) from Aspergillus sp. FSDE 16 by solid-state fermentation (SSF) and use for producing a gluten-free beer.

Beer is a beverage that contains gluten and cannot be consumed by people with celiac disease. In this context, the enzyme prolyl endoprotease (PEP) can be used to reduce the gluten content in beer. The present study aimed to produce the PEP from Aspergillus sp. FSDE 16 using solid-state fermentation with 5 conditions and comparing with a similar commercial enzyme produced from Aspergillus niger in the production of a gluten-free beer. The results of the performed cultures showed that during the culture, the most increased protease activity (54.46U/mL) occurred on the 4th day. In contrast, for PEP, the highest activity (0.0356U/mL) was obtained on the 3rd day of culture in condition. Regarding beer production, cell growth, pH, and total soluble solids showed similar behavior over the 7 days for beers produced without enzyme addition or with the addition of commercial enzyme and with the addition of the enzyme extract produced. The addition of the enzyme and the enzyme extract did not promote changes, and all the beers produced showed similar and satisfactory results, with acid pH between 4 and 5, total soluble solids ranging from 4.80 to 5.05, alcohol content ranging from 2.83% to 3.08%, and all beers having a dark character with deep amber and light copper color. Gluten removal was effectively using the commercial enzyme and the enzyme produced according to condition (v) reaching gluten concentrations equal to 17±5.31 and 21.19±11.28ppm, respectively. In this way, the production of the enzyme by SSF and its application in the removal of gluten in beer was efficient.

De novo biosynthesis of the hops bioactive flavonoid xanthohumol in yeast

The flavonoid xanthohumol is an important flavor substance in the brewing industry that has a wide variety of bioactivities. However, its unstable structure results in its low content in beer. Microbial biosynthesis is considered a sustainable and economically viable alternative. Here, we harness the yeast Saccharomyces cerevisiae for the de novo biosynthesis of xanthohumol from glucose by balancing the three parallel biosynthetic pathways, prenyltransferase engineering, enhancing precursor supply, constructing enzyme fusion, and peroxisomal engineering. These strategies improve the production of the key xanthohumol precursor demethylxanthohumol (DMX) by 83-fold and achieve the de novo biosynthesis of xanthohumol in yeast. We also reveal that prenylation is the key limiting step in DMX biosynthesis and develop tailored metabolic regulation strategies to enhance the DMAPP availability and prenylation efficiency. Our work provides feasible approaches for systematically engineering yeast cell factories for the de novo biosynthesis of complex natural products.

Gluten reduction in beer: Effect of sorghum:quinoa ratio and protein rest time on brewing parameters and consumer acceptability

The combined effects of the grist composition (sorghum:quinoa ratio) and mashing conditions (protein rest time) were investigated with the aim to reduce gluten content in beer and to evaluate their impact on the physicochemical parameters and consumers' acceptability of final beer. Principal Component Analysis results, which explained 72.65% of data variability, showed a good separation of beer samples according their grist composition. Using high sorghum concentrations (34 and 40%) led to a significant reduction (p < 0.05) in extract, Free Amino Nitrogen (FAN), alcohol, total nitrogen content and the colour of the final beer. Protein rest time showed a significant impact on the sensory attributes of beer samples; therefore, it should not exceed 30 min. Beer with the best brewing performance in terms of physicochemical attributes and consumers’ preference (considered as “like moderately” by 90 consumers) was formulated with 6 and 34% of unmalted sorghum and quinoa, respectively, and by performing 20 min of protein rest. Results from this study suggested that the use in brewing of unmalted sorghum and quinoa, in an optimized combination, allows to develop beer brewed with unconventional grains without adversely affect consumer acceptance and purchase intention.

Yeast Strains and Wort Color as Factors Affecting Effects of the Ethanol Fermentation Process

Dark malts used in the production of brewing wort affect the ethanol fermentation process, the phenolic content, antioxidant capacity and the physiology of yeast cells. An innovative element of this research is the combination of investigating the effect of beer wort color modulated by the use of dark specialty malts on the course and effects of fermentation and the characteristics of post-fermentation yeast biomass of brewer’s strains with different characteristics. Dark and pale beer were obtained. The beers had different ethanol contents (4.51–5.79% v/v), resulting from real (62.29–80.36%) and apparent (75.37–98.26%) attenuation levels. Metabolic and morphological differences were demonstrated in the brewer’s yeast strains used. S. cerevisiae var. diastaticus was distinguished by its ability to ferment dextrin, resulting in the highest ethanol content in beers. The total phenolic content in beer depends on the color of the wort and the yeast strain used (244.48–547.56 mg of gallic acid/L). Dark beers show higher ferric ion reduction ability (FRAP) and antioxidant capacity (ABTS•+) than pale beers fermented with the same yeast strains. Through biomass analysis, differences in yeast cell physiology depending on yeast strain and beer wort color were also revealed.

Authentication of craft and industrial beers by excitation-emission matrix fluorescence spectroscopy and chemometrics

In this article, some ingenious strategies based on chemometrics were proposed to achieve the authentication of industry and craft beers in the Chinese market. Excitation-emission matrix fluorescence spectroscopy technique was used to obtain high-dimensional data of beer samples with 3 dilution levels (the content of beer in water = 3%, 50% and 100%). Alternating trilinear decomposition (ATLD) and alternating quadrilinear decomposition (AQLD) algorithms were used to characterize beer samples. Three chemical pattern recognition methods including partial least squares-discrimination analysis (PLS-DA), principal component analysis-linear discriminant analysis (PCA-LDA) and random forest (RF) were used to handle two classification tasks with different aims, including the classification of industry beer and craft beer (Case 1) and the classification of industry beer and craft beers of different brands (Case 2). For case 1, the correct classification rates of the cross-validation, training set, test set and prediction set are all 100% obtained by the classification methods based on four-way data arrays. For case 2, the results obtained by PLS-DA based on four-way data are excellent, the correct classification rates of cross-validation, training set, test set and prediction set are 90.3%, 100.0%, 100% and 88.9%, respectively. This study showed that four-way data coupled with PLS-DA could be a good choice for all beer classification tasks. The proposed method is expected to safeguard the interests of consumers and manufacturers, and it can be extended to the authentication of other beverages.

Quick and Cheap Colorimetric Quantification of Proteins Using 96-Well-Plate Images

Students quantified the protein content in beer, milk, powdered milk, and whey protein using the Bradford assay. The assay was carried out using absorbance measured at 595 nm (standard method) and 96-well-plate images (proposed method). They built analytical curves using bovine serum albumin (BSA) and casein and determined that protein type affected the Bradford assay. They also determined figures of merit such as the limit of detection (LOD), the limit of quantification (LOQ), linear working range, sensitivity, precision (standard deviation, F-test), and accuracy (percent error, t test). In addition, an interference test was carried out using nitrogen-rich compounds, organic bases, and amino acids, and it was shown that the Bradford assay was not affected by these compounds. Student learning outcomes were assessed by a final test using Microsoft Forms. As a learning model, students can determine the protein content in various food samples using just sample dilution, without the need for intricate sample preparation procedures.

Performance of Wild Non-Conventional Yeasts in Fermentation of Wort Based on Different Malt Extracts to Select Novel Starters for Low-Alcohol Beers

Nowadays, the increasing interest in new market demand for alcoholic beverages has stimulated the research on useful strategies to reduce the ethanol content in beer. In this context, the use of non-Saccharomyces yeasts to produce low-alcohol or alcohol-free beer may provide an innovative approach for the beer market. In our study, four wild non-Saccharomyces yeasts, belonging to Torulaspora delbrueckii, Candida zemplinina and Zygosaccharomyces bailii species, were tested in mixed fermentation with a wild selected Saccharomyces cerevisiae strain as starters for fermentation of different commercial substrates used for production of different beer styles (Pilsner, Weizen and Amber) to evaluate the influence of the fermentative medium on starter behaviour. The results obtained showed the influence of non-Saccharomyces strains on the ethanol content and organoleptic quality of the final beers and a significant wort–starter interaction. In particular, each starter showed a different sugar utilization rate in each substrate, in consequence of uptake efficiency correlated to the strain-specific metabolic pathway and substrate composition. The most suitable mixed starter was P4-CZ3 (S. cerevisiae–C. zemplinina), which is a promising starter for the production of low-alcohol beers with pleasant organoleptic characteristics in all the tested fermentation media.

Effect of dissolved oxygen on the oxidative and structural characteristics of protein in beer during forced ageing

SummaryOxygen is contributing to the deterioration of the beer and shortening the shelf‐life of the packaged product. The effect of dissolved oxygen (DO) on oxidative and structural characteristics of protein in beer during forced ageing was examined. Results showed that increased DO decreased obviously protein content in beer, and further reduced antioxidant activities of beer and lipid transfer protein 1 (LTP1). Meanwhile, the increase of DO decreased significantly the free thiol groups content and enhanced the disulfide bonds level in beer and LTP1. Results from circular dichroism, surface hydrophobicity and zeta‐potential illustrated that the increase of DO dramatically changed the secondary and tertiary structure of LTP1 with the decrease in the surface hydrophobicity, α‐helix and β‐turn contents, and the increase in the random coil and negative zeta potential. These results indicated that increased DO could damage the structure of LTP1 and had a negative impact on oxidative stability of beer.

Fate of the mycotoxins in the wort and yeast during ale and lager fermentation and their evaluation under different technological parameters

This study aimed to evaluate the mycotoxins transfer in the wort and yeast during ale and lager fermentation, secondary fermentation, and beer storage. Four yeasts were used to ferment wort contaminated with DON and ZEN. The wort was fermented with two S. cerevisiae yeasts (yeasts A and B) at 15, 20, 25 °C for 96 h, and two S. pastorianus (yeasts C and D) at 10, 15, 20 °C for 144 h. After fermentation, the two wort with the highest mycotoxin decrease were selected for a second fermentation and stored period. Mycotoxins were extracted using QuEChERS and analyzed by UHPLC-DAD/FLD. In the wort, DON decreased from 11% to 27%, locating it adsorbed on the yeast from LOD to 6.16%. ZEN in the wort decreased from 29% to 90%, locating it adsorbed on the yeast from 5.41% to 33.86%. Ale-fermentation process obtained the highest decrease of ZEN in the wort, whereas, for DON, there was no significant difference in the reduction between the 2 fermentation styles. Finally, there was no significant change in mycotoxin content during storage. Knowledge of the mitigating effect of fermentation variables could help to reduce the mycotoxin content in beer.

Beer and beer-based beverage contain lignans.

Lignans are members of a broad group of plant phenols that can positively affect human health. They occur in negligible quantities in processed foodstuffs such as lager beer. The aim of this work was to utilize the high levels of lignans in the knots of spruce trees (Picea abies) to increase the lignans content in beer, without negatively impacting the natural taste and aroma. By means of lignans addition in the forms of spruce knot chips or different extracts made from spruce knots during the wort boiling were produced beer and beer-based beverages with lignans content ranging from 34 to 174mg/L.

Low Lactic Acid-Producing Strain of Lachancea thermotolerans as a New Starter for Beer Production.

Growing consumer interest in new beer flavors is contributing to the application of innovative materials and non-Saccharomyces yeast in brewing. The goal of this study was to test the impact of the low lactic acid-producing Lachancea thermotolerans MN477031 strain on the process of fermenting beer wort, with two different concentrations of bitter compounds, and on the quality of the beer produced. Qualify factors were broadly analyzed, including ethanol content, apparent degree of fermentation, sugars, organic acids, free amino nitrogen, glycerol, volatile compounds, ions and so on. It was proven that the L. thermotolerans MN477031 strain demonstrated a high capacity for rapid initiation of wort fermentation, and a tolerance to hop-derived compounds. As a result, the alcohol content in beer from this method of production was approximately 20% lower, while the content of the real extract was significantly higher in comparison to commercial Safbrew T-58. This strain stands out from many strains of L. thermotolerans due to the low lactic acid production and only marginal influence on pH decrease compared to Saccharomyces cerevisiae. Therefore, the potential of MN477031 in the production of different types of beer (not only sour) is very high. The composition of volatile compounds in L. thermotolerans beer differs—not only in terms of the use of the strain, but also in hop variety.

Fast and selective method for biogenic amines determination in wines and beers by ultra high-performance liquid chromatography

A new approach for biogenic amines (BA) determination in fermented beverages was developed coupling ultrafast dansylation conditions with ultra-high-performance liquid chromatography (UHPLC) method. Derivatization conditions for 8 amines analysis were optimized using D-optimal and central composite designs reducing in 88% the reaction time. Dansylated amines were separated on C18 column using a mobile phase composed of ammonium formate buffer and acetonitrile. Detection was performed by UV and fluorescence. Migration from conventional HPLC to UHPLC allowed a 60% reduction in analysis. The developed method was validated following ICH recommendations. Calibration data fitted a linear regression model with R2 were values highest to 0.984. Repeatability and intermediate precision in matrix showed relative standard deviation (RSD) values lower than 4.86 and 11.53%, respectively. Detection and quantification limits ranged from 0.03 to 0.18 and from 0.20 to 0.59 mg mg L−1. BA content in beer and wine samples were 10.53 to 73.17 mg L−1.

Generation of the Antioxidant Hydroxytyrosol from Tyrosol Present in Beer and Red Wine in a Randomized Clinical Trial.

Beer and wine contains the simple phenol tyrosol (TYR) which is endogenously converted into hydroxytyrosol (HT), one of the strongest dietary antioxidants, by CYP2A6 and CYP2D6 polymorphic enzymes. We investigated in humans the rate of this bioconversion after beer and red wine (RW) intake. In a single blind, randomized, crossover, controlled clinical trial (n = 20 healthy subjects), we evaluated TYR absorption and biotransformation into HT following a single dose of (i) RW, (ii) Indian pale ale beer (IPA), (iii) blonde beer, and (iv) non-alcoholic beer (free). Individuals were genotyped for CYP2A6 and CYP2D6, and a polygenic activity score (PAS) was derived. RW triggered the highest increase in total TYR recovered, followed by IPA, blonde, and free beers. Although the HT content in beer was minimal, an increase in HT production was observed in all beers following TYR in a dose-response manner, confirming TYR to HT biotransformation. Sex differences were identified in the rate of the conversion following RW. PAS scores correlated linearly with the recoveries of HT (HT:TYR ratios) after RW intake. In conclusion, after beer and RW consumption, TYR is absorbed and endogenously biotransformed into HT. This mechanism could be modulated by sex, genetics, and matrix components.

Using a Flatbed Scanner and Automated Digital Image Analysis To Determine the Total Phenolic Content in Beer

Here, students determine the total phenolic content in beers using the Folin–Ciocalteu assay. The Folin–Ciocalteu reagent is a yellow complex, in an alkaline medium; it reacts with phenols and non-phenolic reducing substances to form a blue complex. Quantitative analysis was carried out using absorbance measured at 765 nm (standard method) and digital images (proposed method). In the proposed method, samples were placed in a 96 microwell plate; then, a plate image was obtained with a flatbed scanner. The ImageJ plugin ReadPlate extracts red (R)-values from all wells of the scanned image at the same time; then, R-values were exported to a spreadsheet that converted these values to absorbances. Using absorbances obtained with R-values, the spreadsheet also provides standard calibration plots, limits of detection (LODs), limits of quantification (LOQs), and beer sample total phenolic contents. The proposed method and the standard method were compared using two-tailed significance tests; students observed that both methods provide equivalent results, that both methods were linear in a 2–10 mg L–1 gallic acid concentration range, and that both methods had close LODs and LOQs, 0.55 and 1.70 gallic acid mg L–1, respectively. Beer sample total phenolic contents were compared using one-tailed significance tests. This laboratory experiment provides an effective instrumental alternative to spectrophotometric methods, which can be especially beneficial, where purchasing and maintaining a spectrophotometer is a challenge, and it also presents to the students one-tailed and two-tailed significant tests.

Influence of d-Amino Acids in Beer on Formation of Uric Acid.

SUMMARYExcessive intake of beer could increase serum uric acid levels, leading to high risk of gout, which was previously attributed to high purine content in beer. Recent reports that purine-rich vegetables and bean products do not cause higher uric acid levels do not support this theory. Why excessive intake of beer could increase a high risk of gout has been unclear. Other factors affecting the accumulation of uric acid in the blood have been explored. Beer contains relatively high levels of d-amino acids due to the racemization of l-amino acids induced by food processing. d-amino acid was catalyzed by d-amino acid oxidase to produce H2O2, which is further oxidized in the presence of Fe2+ to produce hydroxyl radicals, resulting in DNA damage and formation of a large amount of purine bases, which are oxidized to uric acid by a series of enzymes. Some food ingredients, such as vitamins and I–, prompt d-amino acids to form uric acid. d-amino acids in beer are one of the key factors responsible for the increase in uric acid levels. The biological response of d-amino acids could explain gout occurrence in beer drinkers.

Biochemical Characterization of Kluyveromyces lactis Adenine Deaminase and Guanine Deaminase and Their Potential Application in Lowering Purine Content in Beer.

Excess amounts of uric acid in humans leads to hyperuricemia, which is a biochemical precursor of gout and is also associated with various other disorders. Gout is termed as crystallization of uric acid, predominantly within joints. The burden of hyperuricemia and gout has increased worldwide due to lifestyle changes, obesity, and consumption of purine-rich foods, fructose-containing drinks, and alcoholic beverages. Some of the therapies available to cure gout are associated with unwanted side-effects and antigenicity. We propose an attractive and safe strategy to reduce purine content in beverages using enzymatic application of purine degrading enzymes such as adenine deaminase (ADA) and guanine deaminase (GDA) that convert adenine and guanine into hypoxanthine and xanthine, respectively. We cloned, expressed, purified, and biochemically characterized both adenine deaminase (ADA) and guanine deaminase (GDA) enzymes that play important roles in the purine degradation pathway of Kluyveromyces lactis, and demonstrate their application in lowering purine content in a beverage. The popular beverage beer has been selected as an experimental sample as it confers higher risks of hyperuricemia and gout. Quantification of purine content in 16 different beers from the Indian market showed varying concentrations of different purines. Enzymatic treatment of beer samples with ADA and GDA showed a reduction of adenine and guanine content, respectively. These enzymes in combination with other purine degrading enzymes showed marked reduction in purine content in beer samples. Both enzymes can work at 5.0–8.0 pH range and retain >50% activity at 40°C, making them good candidates for industrial applications.

Quantifying Beer Bitterness: An Investigation of the Impact of Sample Preparation

Much of analytical chemistry involves the analysis of complex mixtures, where careful attention to sample preparation and method selectivity is required to avoid interferents and obtain accurate data. As this type of analysis is very different from simple colorimetric analysis that most students are exposed to in general chemistry, this laboratory exercise was developed to help students discover the importance of sample preparation, specifically extraction and pH adjustment, for quantifying the “bitterness” derived from iso-α-acid content in beer. In this exercise, students deviate from the standard UV–vis absorbance method and compare calculated bitterness (i.e., iso-α-acid concentration) to the beer manufacturer’s reported bitterness, helping them clarify how the standard method works and why the beer must be “cleaned up” prior to analysis.

An instrument-free method based on visible chemical waves for quantifying the ethanol content in alcoholic beverages

An alternative approach using visible chemical waves for ethanol determination is presented. The method is based on the dynamic change of chemical waves in the Belousov-Zhabotinsky (BZ) reaction by perturbation with ethanol. The observablepropagating waves, generatedina Petri dish, can be recorded by using a smartphone camera. The propagating distances are measured from photographic images and then plotted as a function of time to attain the wave velocity. It is found that wave velocities are inversely proportional to ethanol concentrations. By using this linear relationship, the ethanol content can be efficiently quantified with good intra-day and inter-day precision (<3% RSD). Validated by the GC technique, the developed method is highly reliable and successfully applied for quantifying the ethanol content in beer, colored whisky, and vodka samples. Hence, this new method provides an alternative practical strategy for simple quantitative detection of ethanol without the need for instruments.

Alcohol Determination of Malt-Based Beverages by Rapid Distillation

ABSTRACTThe objective of the study was to assess a rapid distillation unit as an alternative to standard distillation (Beer-4A). A rapid distillation unit (Vapodest 200 by Gerhardt Analytical Systems) was selected as an alternative for its ability to rapidly distill using the power of steam. The NIR/density method (Beer-4G) is quite suitable for measuring the alcohol content of beer; however, flavored malt beverages present a challenge. Deviations between results by the NIR/density method versus results by distillation can occur due to flavor additions and/or high alcohol content. A more accurate way to measure alcohol in this type of product is to first perform a standard distillation (Beer-4A). Unfortunately, this method is time consuming and labor intensive. A precision study was performed to determine repeatability and reproducibility. Three analysts distilled five malt-based products including both beer and flavored malt beverages with alcohol levels ranging from 4.2 to 14.4% (v/v). Repeatability and reproducibility coefficients of variation for the determination of alcohol for this range were 0.05–0.23% and 0.11–0.19%, respectively. In addition, results from Beer-4A and rapid distillation were assessed using a paired t test for alcohol levels ranging from 3.6 to 14.4% (v/v). The P value of 0.30 indicated that there was not a statistically significant difference between the means of the data sets at a 95% confidence level.