Characterization of Key Odor-Active Compounds in Draft Beers for the Chinese Market Using Molecular Sensory Science Approaches.

Beer is a popular alcoholic beverage worldwide. However, limited research has been conducted on identifying key odor-active components in lager-type draft beers for the Chinese market. Therefore, this study aims to elucidate the odor characteristics of the four most popular draft beer brands through a sensory evaluation and an electronic nose. Subsequently, the four draft beers were analyzed through solid-phase microextraction and liquid-liquid extraction using a two-dimensional comprehensive gas chromatography-olfactometry-mass spectrometry analysis (GC×GC-O-MS). Fifty-five volatile odor compounds were detected through GC×GC-O-MS. Through an Aroma Extract Dilution Analysis, 22 key odor-active compounds with flavor dilution factors ≥ 16 were identified, with 11 compounds having odor activity values > one. An electronic nose analysis revealed significant disparities in the odor characteristics of the four samples, enabling their distinct identification. These findings help us to better understand the flavor characteristics of draft beer and the stylistic differences between different brands of products and provide a theoretical basis for objectively evaluating the quality differences between different brands of draft beer.

Methods for Estimating the Detection and Quantification Limits of Key Substances in Beer Maturation with Electronic Noses.

To evaluate the suitability of an analytical instrument, essential figures of merit such as the limit of detection (LOD) and the limit of quantification (LOQ) can be employed. However, as the definitions k nown in the literature are mostly applicable to one signal per sample, estimating the LOD for substances with instruments yielding multidimensional results like electronic noses (eNoses) is still challenging. In this paper, we will compare and present different approaches to estimate the LOD for eNoses by employing commonly used multivariate data analysis and regression techniques, including principal component analysis (PCA), principal component regression (PCR), as well as partial least squares regression (PLSR). These methods could subsequently be used to assess the suitability of eNoses to help control and steer processes where volatiles are key process parameters. As a use case, we determined the LODs for key compounds involved in beer maturation, namely acetaldehyde, diacetyl, dimethyl sulfide, ethyl acetate, isobutanol, and 2-phenylethanol, and discussed the suitability of our eNose for that dertermination process. The results of the methods performed demonstrated differences of up to a factor of eight. For diacetyl, the LOD and the LOQ were sufficiently low to suggest potential for monitoring via eNose.

Examination of internal metabolome and VOCs profile of brewery yeast and their mutants producing beer with improved aroma.

Volatile organic compounds (VOCs) are metabolites pivotal in determining the aroma of various products. A well-known VOC producer of industrial importance is Saccharomyces cerevisiae, partially responsible for flavor of beers and wines. We identified VOCs in beers produced by yeast strains characterized by improved aroma obtained in UV-induced mutagenesis. We observed significant increase in concentration of compounds in strains: 1214uv16 (2-phenylethyl acetate, 2- phenylethanol), 1214uv31 (2-ethyl henxan-1-ol), 1214uv33 (ethyl decanoate, caryophyllene). We observed decrease in production of 2-phenyethyl acetate in strain 1214uv33. Analysis of intracellular metabolites based on 1H NMR revealed that intracellular phenylalanine concentration was not changed in strains producing more phenylalanine related VOCs (1214uv16 and 1214uv33), so regulation of this pathway seems to be more sophisticated than is currently assumed. Metabolome analysis surprisingly showed the presence of 3-hydroxyisobutyrate, a product of valine degradation, which is considered to be absent in S. cerevisiae. Our results show that our knowledge of yeast metabolism including VOC production has gaps regarding synthesis pathways for individual metabolites and regulation mechanisms. Detailed analysis of 1214uv16 and 1214uv33 may enhance our knowledge of the regulatory mechanisms of VOC synthesis in yeast, and analysis of strain 1214uv31 may reveal the pathway of 2-ethyl henxan-1-ol biosynthesis.

Real-time monitoring of the pH of white wine and beer with colorimetric sensor arrays (CSAs).

The real-time monitoring of the pH values of alcoholic beverages was performed with a compact wireless device based on a colorimetric detection method with the Hue (H) as the analytical signal working in a pH range of 2.50-6.50. This device represents the first colorimetric pH meter reported in the literature monitoring in real-time the pH value of colored solutions. This pH meter consists of I) a nitrocellulose membrane impregnated with a pH-sensitive gel; II) a CCD camera for color acquisition; III) an electronic board with the calibration profiles of H vs. pH, and IV) a display to read the measured pH. It was applied to the pH determination of a white wine, a prosecco white wine, and a double malt beer leading to the values of pHwine= 3.30, pHprosecco= 3.33, pHbeer = 4.29. The analytical performance is comparable to the glass electrode with an accuracy error ≤ 0.05 pH units.

Impact of non-Saccharomyces yeasts derived from traditional fermented foods on beer aroma: Analysis based on HS-SPME-GC/MS combined with chemometrics.

In recent years, numerous studies have demonstrated the significant potential of non-Saccharomyces yeasts in aroma generation during fermentation. In this study, 134 strains of yeast were isolated from traditional fermented foods. Subsequently, through primary and tertiary screening, 28 strains of aroma-producing non-Saccharomyces yeast were selected for beer brewing. Headspace-solid phase microextraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC-MS) and chemometrics were employed to analyze the volatile flavor substances in beer samples fermented using these strains. Chemometric analysis revealed that distinct species of non-Saccharomyces yeast had a unique influence on beer aroma, with strains from the same genus producing more similar flavor profiles. Accordingly, 2,6-nonadienal, 1-pentanol, phenyl ethanol, isoamyl acetate, ethyl caprate, butyl butyrate, ethyl propionate, furfuryl alcohol, phenethyl acetate, ethyl butyrate, ethyl laurate, acetic acid, and 3-methyl-4 heptanone were identified as the key aroma compounds for distinguishing among different non-Saccharomyces yeast species. This work provides useful insights into the aroma-producing characteristics of different non-Saccharomyces yeasts to reference the targeted improvement of beer aroma.

Use of Botanical Ingredients: Nice Opportunities to Avoid Premature Oxidation of NABLABs by Increasing Their ORAC Values Strongly Impacted by Dealcoholization or Pasteurization.

Even when fresh, non-alcoholic, and low-alcoholic beers (NABLABs) exhibit significant staling defects due to premature oxidation. In this study, the antioxidant power of eleven fresh commercial NABLABs was assessed by means of three different assays: the oxygen radical absorbance capacity (ORAC), the linoleic acid-induced oxidation (TINH), and the indicator time test (ITT). Only the first two assays, both involving radicalar degradations initiated by AAPH, were found to correlate with each other. NABLABs displayed lower ORAC values than conventional beers (on average, 6127 µmol eq. Trolox/L), except for three samples made with special-colored malts or dry-hopped. Dealcoholization was the step with the greatest impact on the ORAC value (up to a 95% loss) and on flavan-3-ols, sotolon, and polyfunctional thiols, while pasteurization strongly affected color, TBA, and Strecker aldehydes. ORAC assays applied to hop, alternative cereals, and various botanical ingredients indicated that mashing with red sorghum, dry hopping/spicing, and wood maturation could bring the antioxidant power of a NABLAB close to those of conventional beers. With an ORAC value not reached by any other tested botanical ingredient (5234 µmol eq. Trolox/g), African Vernonia amygdalina leaves (traditionally used for Rwandan Ikigage beers) emerged here as the best candidate.

Barley-derived beer brewing by-products contain a high diversity of hydroxycinnamoylagmatines and their dimers.

To aid valorisation of beer brewing by-products, more insight into their composition is essential. We have analysed the phenolic compound composition of four brewing by-products, namely barley rootlets, spent grain, hot trub, and cold trub. The main phenolics detected were hydroxycinnamoylagmatines and dimers thereof. Barley rootlets contained the highest hydroxycinnamoylagmatine content and cold trub the highest dimer content. Additionally, variations in (dimeric) hydroxycinnamoylagmatine composition and content were observed in fourteen barley rootlet samples. The most abundant compound in all rootlets was the glycosylated 4-O-7'/3-8'-linked heterodimer of coumaroylagmatine and feruloylagmatine, i.e. CouAgm-4-O-7'/3-8'-(4'Hex)-DFerAgm. Structures of glycosylated and hydroxylated derivatives of coumaroylagmatine were elucidated by NMR spectroscopy after their purification from a rootlet extract. An MS-based decision tree was developed, which aids in identifying hydroxycinnamoylagmatine dimers in complex mixtures. In conclusion, this study shows that the diversity of phenolamides and (neo)lignanamides in barley-derived by-products is larger than previously reported.

In-depth analysis of volatolomic and odorous profiles of novel craft beer by permutation test features selection and multivariate correlation analysis.

This research explored the impact of binary cereal blends [barley with durum wheat (DW) and soft wheat (CW)], four autochthonous yeast strains (9502, 9518, 14061 and 17290) and two refermentation sugar concentrations (6-9 g/L), on volatolomics (VOCs) and odour profiles of craft beers using unsupervised statistics. For the first time, we applied permutation test to select volatiles with higher significance in explaining variance among samples. The unsupervised approach on the 19 selected VOCs revealed cereal-yeast interaction to be the main source of variability and DW-9502-6/9, DW-17290-6, CW-17290-6 and CW-9518-6 being the best technological strategies. In particular, in samples DW-9502-6/9, concentrations of some of the selected volatiles were observed to be approximately three to more than seven times higher than the average. PLS-correlation between VOCs and odour profiles proved to be very useful in assessing the weight of each of the selected VOCs on the perception of odour notes.

Unconventional raw materials used in beer and beer-like beverages production: Impact on metabolomics and sensory profile.

Beer is the third most consumed beverage in the world, trailing only water and tea but ranking first among alcoholic beverages. In recent years, producers and researchers have shown a growing interest in brewing diversification and innovation, due to of the widespread consumption of beer. In order to create beers and beer-like products with unique and consumer-pleasing characteristics, the use of unconventional raw materials has become a subject of intensive research. The purpose of this paper is to identify, evaluate and summarize the findings of all relevant unconventional raw materials used in relevant scientific studies, as well as the effect on the metabolomics of beer and beer-like beverages.For the enhancement of beer characteristics, the production process may involve the use of an extremely diverse variety of unconventional raw materials that are not included on thelist of usual ingredients for the beer industry. However, the general trend is to use locally available ingredients as well as functional ingredients. Twoof the most studied functional characteristics involve phenolic compounds and antioxidant activity, which is why the fruit is by far the most commonly used adjunct category, as fruits are particularly important sources of polyphenols and antioxidants. Other uncommon adjuncts used in brewing includeplants, starch sources, spices or even propolis. Moreover, unconventional raw materials are used to enhance the sensory profile by create new characteristics such as new tastes and flavors, accentuation of the cooling sensation or even increasing acceptability among potential consumers, who do not appreciate traditional beers due to their specific characteristics.

Multipoint monitor of beer fermentation.

This short communication is devoted to a fully-mechanized flow analysis system for the control of beer fermentation process. The developed system is based on microsolenoid flow controlling devices (valves and pumps) and a flow-through optoelectronic detector. All these components are powered and controlled by a Adruino-compatible microprocessor platform that creates an integrated, compact, and robust analytical tool. Multiplication of sample aspiration ports of the analytical system allows for simultaneous monitoring of several independently performed fermentation processes, as well as a single process at the different places of fermentation tank. To demonstrate its practical utility, the developed system has been applied for online and real-time monitoring of yeast propagation and distribution in beer worts in the course of various fermentation processes. Potentially, this flow analysis system can be easily expanded to the form of multianalyte monitor equipped with optoelectronic sensors and biosensors for the determination of other parameters and analytes.

Nanozymes sensor array for discrimination and intelligent sensing of phenolic acids in food.

Although nanozymes sensor arrays have the potential to recognize multiple target substances simultaneously, they currently rarely identify phenolic acids in food due to limited catalytic performance and complex preparation conditions of nanozymes. Here, inspired by the structure of polyphenol oxidase, we have successfully prepared a novel gallic acid-Cu (GA-Cu) nanozyme with laccase-like activity. Due to the different catalytic efficiency of GA-Cu nanozymes towards six common phenolic acids, a three-channel colorimetric sensor array was constructed using reaction kinetics as the sensing unit to achieve high-throughput detection and identification of six phenolic acids within a concentration range from 1 to 100 µM. This method avoids the creation of numerous sensing units. Notably, the successful discrimination of six phenolic acids in samples of juice, beer, and wine has been achieved by the sensor array. Finally, aided by smartphones, a portable technique has been devised for the detection of phenolic acids.

New insights into the characteristic flavor components of traditional sour beers such as Lambic and Flanders Red Ale beers.

In recent years, the demand for beers with a variety of flavors has increased considerably owing to the diversification of consumer preferences. Sour beer is characterized by a sour taste unlike normal beer flavor, and previous studies on sour beer have been primarily focused on addressing issues, such as inconsistent product quality and long production time, and on the associated microorganisms. Scientific knowledge regarding the characteristic flavor of sour beer and flavor components is limited. Therefore, in this study, we aimed to clarify the characteristic sensory attributes of sour beer and the component profiles that explain these attributes. Component analysis was performed on 10 traditional sour beers (eight Flanders Red Ales and two Lambics), using untargeted gas chromatography-mass spectrometry with liquid-liquid extraction, liquid chromatography-mass spectrometry targeting amines and anionic compounds. Further, sensory evaluation was conducted by well-trained panelists via quantitative descriptive analysis. Orthogonal partial least squares regression analysis was also conducted to investigate candidate flavor components. Thus, 261 components were identified and our methods could explain the flavor attributes of the examined samples. Comprehensive component profiling data also showed that differences in fermentation method, barrel aging duration, and blending ratio affected beer flavor. Further, Lambics were found to be characterized by citrus and phenolic aroma, while Flanders Red Ales were characterized by solvent-like aroma, sourness complexity, full bodied, graininess, astringency, and bitterness. These findings may serve as a basis for addressing issues related to sour beer production and may facilitate process design for obtaining targeted sour beer flavors.

Naked-eye sensitive detection of nanoPET by pH-responsive colorimetric method based on dual-enzyme catalysis.

A pH-responsive colorimetric method based on dual-enzyme catalysis for rapid and facile detection and quantification of nanoPET at environment-dependent concentration is proposed. The nanoPET was hydrolyzed by the synergistic catalysis of cutinase and lipase to terephthalic acid which can be sensitive detected using bromocresol purple as the indicator. The color changed from purple to bright yellow as the nanoPET detection concentration increased from 0 mg/mL to 2 mg/mL which can be detected by UV-Vis. This naked-eye method has a high sensitivity for nanoPET detection with the visual detection cutoff of 31.00 µg/mL, and has a good linearity in the range of 0 âˆ¼ 1 mg/mL with LOD of 22.84 µg/mL. The reliability of this method is verified in the detection of nanoPET in lake water and beer samples, with an average recovery of 87.1 %. The as-developed dual-enzyme colorimetric chemosensor holds promising potential as a robust and effective platform for the sensitive detection of nanoPET.

Predicting and improving complex beer flavor through machine learning.

The perception and appreciation of food flavor depends on many interacting chemical compounds and external factors, and therefore proves challenging to understand and predict. Here, we combine extensive chemical and sensory analyses of 250 different beers to train machine learning models that allow predicting flavor and consumer appreciation. For each beer, we measure over 200 chemical properties, perform quantitative descriptive sensory analysis with a trained tasting panel and map data from over 180,000 consumer reviews to train 10 different machine learning models. The best-performing algorithm, Gradient Boosting, yields models that significantly outperform predictions based on conventional statistics and accurately predict complex food features and consumer appreciation from chemical profiles. Model dissection allows identifying specific and unexpected compounds as drivers of beer flavor and appreciation. Adding these compounds results in variants of commercial alcoholic and non-alcoholic beers with improved consumer appreciation. Together, our study reveals how big data and machine learning uncover complex links between food chemistry, flavor and consumer perception, and lays the foundation to develop novel, tailored foods with superior flavors.

A Review of N-Heterocycles: Mousy Off-Flavor in Sour Beer.

Beer has over 600 flavor compounds and creates a positive tasting experience with acceptable sensory properties, which are essential for the best consumer experience. Spontaneous and mixed-culture fermentation beers, generally classified as sour beers, are gaining popularity compared to typical lager or ale styles, which have dominated in the USA for the last few decades. Unique and acceptable flavor compounds characterize sour beers, but some unfavorable aspects appear in conjunction. One such unfavorable flavor is called "mousy". This description is usually labeled as an unpleasant odor, identifying spoilage of fermented food and beverages. It is related as having the odor of mouse urine, cereal, corn tortilla chips, or freshly baked sour bread. The main compounds responsible for it are N-heterocyclic compounds: 2-acetyltetrahydropyridine, 2-acetyl-1-pyrroline, and 2-ethyltetrahydropyridine. The most common beverages associated with mousy off-flavor are identified in wines, sour beers, other grain-based beverages, and kombucha, which may contain heterofermentative lactic acid bacteria, acetic acid bacteria, and/or yeast/fungus cultures. In particular, the fungal species Brettanomyces bruxellensis are associated with mousy-off flavor occurrence in fermented beverages matrices. However, many factors for N-heterocycle formation are not well-understood. Currently, the research and development of mixed-cultured beer and non/low alcohol beverages (NABLAB) has increased to obtain the highest quality, sensory, functionality, and most notably safety standards, and also to meet consumers' demand for a balanced sourness in these beverages. This paper introduces mousy off-flavor expression in beers and beverages, which occurs in spontaneous or mixed-culture fermentations, with a focus on sour beers due to common inconsistency aspects in fermentation. We discuss and suggest possible pathways of mousy off-flavor development in the beer matrix, which also apply to other fermented beverages, including non/low alcohol drinks, e.g., kombucha and low/nonalcohol beers. Some precautions and modifications may prevent the occurrence of these off-flavor compounds in the beverage matrix: improving raw material quality, adjusting brewing processes, and using specific strains of yeast and bacteria that are less likely to produce the off-flavor. Conceivably, it is clear that spontaneous and mixed culture fermentation is gaining popularity in industrial, craft, and home brewing. The review discusses important elements to identify and understand metabolic pathways, following the prevention of spoilage targeted to off-flavor compounds development in beers and NABLABs.

Quantification of Hop-Derived Bitter Compounds in Beer Using Liquid Chromatography Mass Spectrometry.

Hops (Humulus lupulus L.) are essential raw materials for beer brewing, and the major contributors to beer bitterness are isohumulones (iso-α-acids) and humulinones. In recent years, many breweries have focused on the production of hop-forward beer styles by adding hops after or during the cold fermentation stage, which will tend to release humulinones or other hop-derived bitter compounds. In this study, a LC-MS/MS method was developed for quantification of 60 hop-derived bitter compounds in 25 min. Reverse-phase chromatography with an alkaline methanol/acetonitrile (70:30) mobile phase was used for the separation. The quantitative range was 0.053-3912 ng/mL with correlation coefficient r > 0.99, and the LOQ were 0.26 and 0.053 ng/mL for iso-α-acids and humulinones. Precision (RSD < 5.0%) and accuracy (recovery 86.3%-118.1%) were both satisfactory. The abundance of hop-derived bitter compounds in the dry-hopped beer (Double-India Pale Ale) and the nondry-hopped beer (Vienna Lager) were monitored throughout the fermentation and storage stages, and the formation of oxidation and cyclization products showed difference profiles between these two beers. The quantification results reveal how hop-derived bitter compounds change throughout the brewing process, as well as the influence of hops and brewing techniques on beer bitterness.

Unlocking hot trub's potential: a simple method for extracting bitter acids and xanthohumol.

BACKGROUND: Hot trub is a macronutrient- and micronutrient-rich by-product generated in the brewing industry, which is still underrated as a raw material for reprocessing purposes. In this context, this study aimed to investigate the extraction of bitter acids' and xanthohumol from hot trub as well as identify the significance of parameters for the process. The research assessed various extraction parameters, such as pH, ethanol concentration, temperature, and solid-to-liquid ratio, using a Plackett-Burman design. RESULTS: Ethanol concentration and pH were the most significant parameters affecting extraction yield. ß-acids were found to be the principal components of the bitter acids, with a maximum concentration near 16 mg g-1, followed by iso-α-acids and α-acids achieving 6 and 3.6 mg g-1, respectively. The highest yields of bitter acids were observed in the highest ethanol concentration, while pH was relevant to extraction process in treatments with low ethanol ratios. Concerning the xanthohumol extraction, the approach achieved maximum concentration (239 µg g-1) in treatments with ethanol concentration above 30%. Despite their variances, the phytochemicals exhibited comparable extraction patterns, indicating similar interactions with macromolecules. Moreover, the characterization of the solid residues demonstrated that the extraction process did not bring about any alterations to the chemical and total protein profiles. CONCLUSION: Ethanol concentration was found to have the most significant impact on the extraction of bitter acids and xanthohumol, while temperature had no significant effect. The solid remains resulting from the extraction showed potential for use as a protein source. © 2024 Society of Chemical Industry.

Effect of Coriander Seed Addition at Different Stages of Brewing on Selected Parameters of Low-Alcohol Wheat Beers.

In recent years, there has been a significant decline in interest in high-alcohol beers, while interest in low- and non-alcohol beers is growing. The aim of this study was to investigate the influence of the addition of coriander seeds at various stages of the production of low-alcohol wheat beer (mashing, boiling, and fermentation). The presented article uses biological methods to produce low-alcohol beer. For this purpose, first, the mashing process was modified (breaking 44 °C for 20 min, followed by 75 °C for 60 min). The chemical composition and aroma components of the obtained beers were determined using various chromatographic methods (HPLC, GC-MS, and GC-O). Differences were found between the aroma components depending on the stage of production at which the coriander seeds were added. Beers with the addition of coriander seeds at the fermentation stage had the highest terpene content (linalool, camphor, trans-linalool oxide, and γ-terpinene) and boiling (myrcene, limonene, citronellol, and geraniol). The least desirable process is the addition of coriander seeds at the mashing stage due to the lowest content of volatile compounds. Additionally, beers with the addition of coriander seeds for fermentation were characterized by a higher content of antioxidant compounds. This proves that the addition of coriander seeds during beer production could improve the fermentation process and modify the quality of the obtaining beer.

Assessment of green lentil malt as a substrate for gluten-free beer brewing.

The aim of this study was to analyze whether it is possible to brew beer without using cereals so that the produced beverage could be easily accessible for the population suffering from celiac disease and other gluten-related disorders. Green lentil seeds were malted and then mashed using a congress mashing procedure to assess their advantages and disadvantages in the brewing process. Based on the congress mashing procedure, the mashing process needed to produce beer was developed, and beers were produced from the lentil malts germinated during malting for 96 h, 120 h and 144 h. It was possible to produce beers from the lentil malts; however, they were characterized by a lower alcohol content, lower degree of attenuation and some discrepancies between the concentrations of various volatiles (such as acetaldehyde, ethyl acetate, and 1-propanol) compared to the control beer produced from barley malt.

An integrative multi-omics approach aimed to gain insight on the effect of composition, style, yeast, and wheat species on wheat craft beer flavour.

This study was aimed to unravel the effect of raw materials (barley and wheat), wheat concentration (0, 25, 40, and 100 %), wheat species (common and durum), beer style (Blanche and Weiss), and yeast (US-05 and WB-06) on the chemical composition, volatiles, and sensory profile of wheat craft beers by using a multivariate statistical approach. Beer samples were analysed for their composition, volatiles and sensory profile and data were processed using unsupervised multivariate analyses, PLS regression and a multi-omics approach using multi-block PLS-DA. Multi-block variable sparsification was used as an embedded dimension reduction step. The adopted multi-omics approach permitted to correctly classify beers with different styles and wheat concentration, and to accurate classify (95 % accuracy) beers according to yeast type. Wheat species was of lower importance since it permitted a classification with 49 % accuracy which increased to 74 % in Blanche beers, thus suggesting that malting flattened differences determined by wheat species.