GC/MS-based metabolomics study to investigate differential metabolites between ale and lager beers

Chemometric mapping of beer styles: Integration of hordenine into the beer composition fingerprint

The study developed a chemometric map of commercial beer brands of different fermentations (Ale & Lager), grouped into twelve styles, integrating hordenine into the beer fingerprint as a contributor to overall quality traits. Multivariate modeling was used to establish non-obvious relationships between beer ingredients and finished product characteristics such as physicochemical properties, isoalpha-acids, ethanol, and hordenine. Ale beers showed the highest hordenine levels, up to 11.82 mg·L-1, whereas Lager light exhibited the lowest concentration (1.41 mg·L-1). Unexpectedly, hordenine correlated with isoalpha-acids and bitterness (r = 0.69 and 0.71, respectively). Hence, the results indicated that bitterness measurements seem to include spectral contributions from isoalpha-acids and hordenine. Furthermore, beers with wheat malt transformed the Ale beers into a Lager-like chemical and theoretical sensory traits described in style guidelines. New knowledge of the chemistry behind IBUs as a beer quality biomarker seems relevant since bitterness is possibly beer's prominent sensory basic taste.

Characterization of Key Factors Associated with Flavor Characteristics in Lager Beer Based on Flavor Matrix

Lager beer has the characteristics of a refreshing aroma, clean and less intense taste, as well as a low alcohol degree, which is suitable for daily drinking. This study aimed to clarify the relationship between important flavor compounds and flavor profiles for lager beer. Headspace solid-phase microextraction, solvent-assisted flavor evaporation combined with comprehensive two-dimensional gas chromatography-mass spectrometry, gas chromatography-mass spectrometry, and gas chromatography-olfactometry-mass spectrometry were applied for the qualitative and quantitative analysis of the trace components in lager beer. Furthermore, the recombination experiment was successfully applied to simulate the flavor profile, and the omission experiment was conducted to study the effects of flavor compounds on the flavor profile. A total of nine compounds were identified as the key flavor compounds, and their contribution to the flavor characteristics of lager beer was verified according to validation experiments. It was found that the influence of the key flavor compounds on the sensory attributes such as malty aroma, fruity aroma, sweetness, and bitterness varied with their concentration. These findings might provide ideas for the research regarding the flavor compounds and flavor profile of lager beer, and contribute to the development of different types of beer in the future.

Metabolomics and (craft) beers - recent advances

Craft beers have encountered a steady rise in popularity over the years, as these artisanal beers produced by microbreweries have responded to consumer preferences for added novelty in such beverages. With this gain in appeal and interest for the beverage, craft beers have also become a growing industry in many parts of the world, and the same can be said for research within the field. This also extends to the chemistry of craft beers, where one method of exploration involves that of metabolomics, appropriately addressing the multi-faceted aspects of craft beer development and chemistry. Alongside advances in metabolomics in general beer and brewing research, the field also mirrors potential in growth. This review touches on relevant aspects of the beer industry and brewing process as preliminaries for discussions on advances in the field of beer metabolomics, leading to the application of metabolomics in pursuit of studying craft beers; future directions, challenges, and opportunities are also presented.

Metabolomics-based mechanistic insights into antioxidant enhancement in mango juice fermented by various lactic acid bacteria

Lactic acid bacteria (LAB) fermentation can modify the antioxidant capacity of food. This study investigates the impact and mechanisms of various LAB strains (Lactobacillus plantarum NCU116, Lactobacillus acidophilus NCU402, and Lactobacillus casei NCU215) fermentation on the antioxidant properties of mango juice. LAB strains inoculation enhanced the antioxidant activity of mango juice, with metabolomics showing increased in polyphenols and decreased in vitamins and carotenoids, indicating polyphenols as the main contributors. Quantification of polyphenols (free and bound forms) revealed that fermentation decreased bound gallic acid levels while increasing free pyrogallol and 1,2,3,4,6-O-pentagalloylglucose, which mainly contributed to the rise in antioxidant capacity in mango juice. L. acidophilus NCU402 had the highest increase in 1,2,3,4,6-O-pentagalloylglucose (from 918.07 to 1750 μg/10 g), whereas L. casei NCU215 facilitated the greatest release of bound gallic acid (49.29 to 11.77 μg/10 g). Bound polyphenol release may be linked to pectin degradation, with lower galacturonic acid and increased pectinase activity.

Integrative LC-MS and GC-MS metabolic profiling unveils dynamic changes during barley malting

Malting involves complex biochemical transformations affecting sensory and quality attributes. Despite extensive research on storage carbohydrates and proteins in malting, the lack of a detailed metabolic understanding of this process limits our ability to assess and enhance malt quality. This study employed untargeted GC-MS and LC-MS metabolite profiling across six malting timepoints to identify 4980 known metabolites, 82 % of which exhibited significant changes during the malting process. Here we identified stage-dependent metabolic shifts and dynamic chemical classes and pathways between each studied stage. These results can guide the fine-tuning of malting conditions to improve malt quality for beer production and other malt-based applications. Additionally, metabolites with antimicrobial properties were identified, underscoring the interplay between barley and microbial metabolic processes during malting. Further research into these microbial metabolites and cognate microbes may lead to novel malting assessment traits for high-quality and safe malted barley.

Exploitation of Selected Sourdough Saccharomyces cerevisiae Strains for the Production of a Craft Raspberry Fruit Beer

Recent interest in the special beer category has encouraged the search for novel brewing materials, including new ingredients and novel yeast strains, in order to differentiate the finished products. The aim of this work was to select non-brewing S. cerevisiae strains for the production of a fruit beer with raspberry. The in vitro tests and the wort fermentations allowed the selection of two sourdough S. cerevisiae strains, showing high maltose and maltotriose consumption, high ethanol production, and high viability. Fruit beers (FB) and control beers (CB) without raspberries were prepared. Fruit addition accelerated sugar consumption (7 days compared to 13 days) and increased ethanol and glycerol production by yeasts. Raspberry addition and the inoculated yeast strongly affected the aroma profile of beers. FB samples showed a higher amount of volatile organic compounds (VOCs); the most represented classes were alcohols, followed by esters and acids. FB inoculated by the selected S. cerevisiae SD12 showed the highest VOCs concentration (507.33 mg/L). Results highlighted the possible application of sourdough yeast strains for the brewing process, which, combined with raspberry addition, can be exploited for the production of beers with enhanced aromatic features and suitable chemical properties.

Effect of a co-fermentation system with high-GABA-yielding strains on soymilk properties: microbiological, physicochemical, and aromatic characterisations

Biosynthesis is the safest method for preparing GABA; however, there are not enough GABA-producing strains to provide an effective resource. The purpose of this study was to determine the feasibility of using Lactobacillus fermentum SMN10-3(A) and Lactococcus lactis SMN15-6(B) to study the effects of strain complex pairing on the GABA formation, flavour, and metabolic pathways of fermented soymilk. It was found that group A2B1 had the highest acid production rate, GABA yield (1.76 ± 0.01 mg/mL), and flavour compound content. A total of 55 differential metabolites were produced after fermentation, of which 28 dominated by hexanal were significantly downregulated and 26 dominated by alcohols were significantly upregulated. The significant metabolic pathways involved were d-alanine, taurine and hypotaurine, and selenocompound metabolism. Finally, the components contributing to the aroma of fermented soymilk were identified, which included 2-pentylfuran and 2-butyl-2-octenal. These results provide a theoretical basis for future research on GABA-rich fermented foods.

Correlation analysis between jejunum metabolites and immune function in Saba and Landrace piglets

The immune function of the intestinal mucosa plays a crucial role in the intestinal health of hosts. As signaling molecules and precursors of metabolic reactions, intestinal chyme metabolites are instrumental in maintaining host immune homeostasis. Saba (SB) pigs, a unique local pig species in central Yunnan Province, China. However, research on jejunal metabolites in this species is limited. Here, we used immunohistochemistry and untargeted metabolomics by liquid chromatography mass spectrometry (LC-MS/MS) to study differences in jejunal immunophenotypes and metabolites between six Landrace (LA) and six SB piglets (35 days old). The results showed that the levels of the anti-inflammatory factor interleukin 10 (IL-10) were markedly higher in SB piglets than in LA piglets (P < 0.01), while the levels of the proinflammatory factors IL-6, IL-1β, and Toll-like receptor 2 (TLR-2) were markedly lower (P < 0.01). Furthermore, the levels of mucin 2 (MUC2) and zona occludens (ZO-1), which are related to mucosal barrier function, were significantly higher in SB piglets than in LA piglets (P < 0.01), as were villus height, villus height/crypt depth ratio, and goblet cell number (P < 0.05). Differences in jejunal chyme metabolic patterns were observed between the two piglets. In the negative ion mode, cholic acid metabolites ranked in the top 20 and represented 25% of the total. Taurodeoxycholic acid (TDCA) content was significantly higher in SB piglets than in LA piglets (P < 0.01). TDCA positively correlated with ZO-1, villus height, villus height/crypt depth ratio, and goblet cell number. These results suggest that SB pigs have a strong jejunal immune function and that TDCA was positively regulates jejunal immunity and mucosal barrier function. Our findings provide a reference for understanding intestinal immune function in different pig breeds and for the discovery of potential biomarkers to help solve health issues related to pig production.

Adding functional properties to beer with jasmine tea extract

Hops provide the characteristic bitter taste and attractive aroma to beer; in this study, hops were replaced by jasmine tea extract (JTE) during late-hopping. The addition of JTE improved the beer foam stability 1.52-fold, and increased the polyphenol and organic acid contents. Linalool was the most important aroma compound in hopped (HOPB) and jasmine tea beer (JTB), but other flavor components were markedly different, including dimeric catechins, flavone/flavonol glycosides, and bitter acids and derivatives. Sensory evaluation indicated that addition of JTE increased the floral and fresh-scent aromas, reduced bitterness and improved the organoleptic quality of the beer. The antioxidant capacity of JTB was much higher than that of HOPB. The inhibition of amylase activity by JTB was 30.5% higher than that of HOPB. Functional properties to beer were added by substituting jasmine tea extract for hops during late hopping.

Novel Insight into the Formation of Odour-Active Compounds in Sea Buckthorn Wine and Distilled Liquor Based on GC-MS and E-Nose Analysis

Sea buckthorn wine (SW) and distilled liquor (DL) are fruit wines with beneficial health effects. However, their unpleasant flavour limits their development and widespread acceptance. Therefore, it is necessary to analyse their flavour composition and changes. In this study, differential metabolites of sea buckthorn DL during processing were analysed, and the relationships between E-nose sensor values and key volatile organic compounds (VOCs) were established. The results show that 133 VOCs were identified, with 22 aroma-contributing components. Fermentation significantly increased the content of VOCs, especially esters. A total of seven and 51 VOCs were significantly upregulated after fermentation and distillation, respectively. Meanwhile, seven sensors were positively correlated with the increased level of alcohols and esters, and reflected the increasing trends of 10 key VOCs.

Application of Untargeted Metabolomics to Reveal the Taste-Related Metabolite Profiles during Mandarin Fish (Siniperca chuatsi) Fermentation

Spontaneous fermentation is a critical processing step that determines the taste quality of fermented mandarin fish (Siniperca chuatsi). Here, untargeted metabolomics using ultra-high-performance liquid chromatography coupled with Q Exactive tandem mass spectrometry was employed to characterize the taste-related metabolite profiles during the fermentation of mandarin fish. The results demonstrated that the taste profiles of mandarin fish at different stages of fermentation could be distinguished using an electronic tongue technique. Sixty-two metabolites, including amino acids, small peptides, fatty acids, alkaloids, and organic acids, were identified in fermented mandarin fish samples. Additional quantitative analysis of amino acids revealed glutamic acid and aspartic acid as significant contributors to the fresh flavor. Furthermore, the Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis revealed that amino acid metabolism was the dominant pathway throughout the fermentation process. This study provides a scientific and theoretical reference for the targeted regulation of the quality of fermented mandarin fish.

Metabolomics: An analytical technique for food processing evaluation

This review aimed to retrieve the most recent research with strong impact concerning the application of metabolomics analysis in food processing. The literature reveals the high capacity of this methodology to evaluate chemical and organoleptic transformations that occur during food production. Current and potential applications of metabolomics analysis will be addressed, focusing on process-composition-function relationships. The use of the metabolomics approach to evaluate transformations in foods submitted to minimal processes, heat or cold treatments, drying, fermentation, chemical and enzymatic treatments and processes using innovative technologies will be discussed. Moreover, the main strategies and advantages of metabolomics-based approaches are reviewed, as well as the most used analytical platforms. Overall, metabolomics can be seen as an important tool to support academia and industry on pursuing knowledge about the transformation of raw animal or plant materials into ready-to-eat products.

Rapid discrimination of beer based on quantitative aroma determination using colorimetric sensor array

In this study, 6 beers from Tsingtao Brewery were analyzed by using colorimetric GC-MS and sensor array (CSA). First, forty volatile compounds of six beers, including 16 esters, 10 alcohols, 4 acids and 4 aldehydes, were identified by GC-MS. Beers from the same category were grouped using principal component analysis (PCA) score plot and hierarchical clustering analysis (HCA) dendrogram. Discrimination of the beers was subsequently implemented using a 4 × 4 CSA combined with multivariate analysis. A linear discriminant analysis (LDA) model achieved a 100% recognition rates of the 6 beers. In addition, a partial least square (PLS) model could be used to quantitatively determine ethyl octanoate, phenethyl acetate, isoamyl alcohol and octanoic acid, with correlation coefficients over 0.85 for both the calibration curves of the training and prediction sets. Hence, CSA could be used for rapid and non-destructive determination of beer quality.