Beer Fermentation Research Articles

Evidence in Lager Yeasts of β-Lyase Activity Breaking Down γ-GluCys-Conjugates More Efficiently Than Cys-Conjugates to Odorant Beer Polyfunctional Thiols

The prevalence of glutathionylated (G-) precursors of polyfunctional thiols (PFTs) over their free forms has prompted investigating how to optimize the enzymatic breakdown of these precursors with yeast during lager, ale, and non-alcoholic/low-alcoholic beer (NABLAB) fermentation trials. Some Saccharomyces cerevisiae yeasts have been selected for their higher β-lyase activity on the cysteinylated (Cys-) conjugates (up to 0.54% for SafAleTM K-97), yet some S. pastorianus strains and one maltose-negative S. cerevisiae var. chevalieri yeast have proved to release PFTs more efficiently from G-precursors (up to 0.21% for BRAS-45 and 0.19% for SafBrewTM LA-01). The present study aimed to explore the possibility and extent of direct release in the beer of 3-sulfanylhexanol from its synthetic γ-glutamylcysteinylated (γ-GluCys-) precursor. Release efficiency was determined by GC-PFPD after the fermentation (7 days at 24 °C and 3 days at 4 °C) of a 15 °Plato (°P) wort enriched with 15 mg/L of synthesized γ-GluCys-3SHol. Up to a 0.28–0.35% release was measured with S. pastorianus strains BRAS-45 and SafLagerTM E-30, while much lower activities (≤0.16%) were observed with S. cerevisiae yeasts, including the maltose-negative chevalieri variety. This β-lyase activity on γ-GluCys-3SHol has never been described before. Under our experimental conditions, the efficiency of release from γ-GluCys-3SHol was drastically reduced in low-density worts. A strongly strain-dependent impact of temperature was also observed.

Biogenic amines degradation ability of Saccharomyces cerevisiae I45 and Pichia sp. NW5 & LB60 and their application in beer fermentation

Biogenic amines degradation ability of Saccharomyces cerevisiae I45 and Pichia sp. NW5 & LB60 and their application in beer fermentation

Pomegranate Juice Effect on Physicochemical and Nutraceutical Characteristics of a Craft Fruit Beer

While fruit is a common ingredient in beer, our research takes a unique approach by studying the effects of pomegranate juice (PJ) on the physicochemical and nutraceutical characteristics of craft fruit beer. These properties have been studied in PJ and other beverages using pomegranate; however, there is insufficient information on fruit beer. PJ, known for its health benefits, was obtained by compressing the fruit in a manual press and characterizing it. The base beer, a blonde ale with two hops, Cascade (C) and Saaz (S), was used. PJ was added to the beer during the second and third fermentation steps. Beer quality was analyzed using ASBC methods: phenolic compounds, sugars, and ethanol content by HPLC, and antioxidant capacity by ORAC. PJ presented a pH of 3.8 and 14°Brix. The beer evaluated was the third fermentation beer called 3FC and 3FS; due to the type of hops used, in general, 3FS presented better physicochemical characteristics; the relevant result was alcohol content around 6.0%, but ethanol content by HPLC was 7.36% for 3FS and 7.19% for 3FC. PJ in phenolic compounds provides the beer with 4-hydroxybenzoic acid, epicatechin, and synaptic acid. However, the hop used influenced the phenolic profile of each beer. The antioxidant capacity of 3FC was higher at 19.75 mm ET/L. In conclusion, our study demonstrated that pomegranate juice in a fruit beer style provides good physicochemical and nutraceutical characteristics, offering a unique twist to the craft beer industry.

Valorisation of Carbon Dioxide from Fermentation in Craft Brewing: Potential Technologies, Brewer Interviews, and Implication for a ‘Three-Level Valorisation System’

The brewing industry of all sizes is increasingly undertaking various initiatives to comprehend its carbon footprint and to implement measures aimed at mitigating its environmental impacts. To the best of the authors’ knowledge, the present research for the first time investigates technologies and challenges specific to craft brewers in valorising carbon dioxide (CO2) from beer fermentation. A systematic review was conducted by assessing multiple databases and existing commercial development, leading to the identification of three carbon capture technologies. This involves an existing direct CO2 capture unit, as well as emerging microalgae systems and bicarbonate systems. A summary of these technologies was presented to five craft brewers located in the Rhône-Alpes region of France, before conducting semi-structured interviews with them. All the brewers expressed keen interest in exploring avenues to mitigate their carbon emissions, despite their lack of awareness regarding the presented technologies. The results indicated a clear need for technical training, advertisement campaigns, and governmental support to implement the technologies among craft brewers. Furthermore, to address the concerns raised by the interview participants, a three-level valorisation system was proposed. This system involves the cascading use of CO2, enabling the sharing of investments and resources among technologies at a regional community scale. It is anticipated that the study will serve as a valuable resource for craft brewers as they consider small-scale carbon capture solutions. Additionally, it is expected to provide insights for academic, governmental, and business clusters seeking to build local infrastructure to support the implementation of such technologies.

Continuous Primary Beer Fermentation with Yeast Immobilized in Alginate–Chitosan Microcapsules with a Liquid Core

Continuous Primary Beer Fermentation with Yeast Immobilized in Alginate–Chitosan Microcapsules with a Liquid Core

Metabolic Engineering of the purine metabolic pathway in brewers yeast to reduce the Purine components in a Beer System

Beer is one of the most popular beverages in the world. However, beer contains excessive amounts of purines, which can increase the risk of hyperuricaemia and gout. During beer fermentation, a key reason is that the purines are not completely absorbed by yeast, which is due to the insufficient ability of purine salvage pathway in beer yeast. In order to improve the absorption capacity of yeast for purines, this study overexpressed four key genes in the purine metabolism pathway (HPT1, APT1, FCY2, and PRM15) in the commercial beer yeast strain SC4, and obtained three yeast engineering strains, namely M1 (SC4 HPT1:: APT1), M2 (M1:: FCY2), and M3 (M2:: PRM15). The expression of purine metabolism-related genes was examined at the transcriptional level, and the expression levels of HPT1, APT1, FCY2 and PRM15 genes were increased by 3.50-fold, 2.37-fold, 2.07-fold and 4.37-fold, respectively, and the overexpression of FCY2 and PRM15 increased the expression levels of HPT1 and APT1 by 3.50-fold and 2.37-fold, respectively. The expression of FCY2 and PRM15 made HPT1 and APT1 more active, indicating that the ability to absorb purines was further enhanced. Applying engineering yeast M3 to 12-degree wort fermentation, the results shown that the free purine base content is reduced by 53.35%, which provides a theoretical basis for reducing the purine content in beer.

The role of yeast propagation aeration for subsequent primary fermentation with respect to performance and aroma development

SummaryDuring the primary fermentation of beer, the yeast simultaneously carries out a series of processes such as cell growth, pH shift, and the formation and degradation of essential flavour components. Harvested yeast from a previous fermentation can be used to inoculate the fermentation or fresh cells can be produced through aerobic propagation. This study investigated the influence of different aeration conditions during Saccharomyces pastorianus ssp. carlsbergensis propagation on the cell count development and the production of secondary metabolites during the subsequent primary beer fermentation. Propagations were conducted by applying six different dissolved oxygen concentrations, and the cells were used as inoculum for the subsequent fermentation. Cell count, pH shift, and the development of key aroma compounds were monitored throughout the primary fermentation to evaluate any difference between the conducted fermentations. The outcomes revealed significant distinctions between fermentations using yeast propagated under elevated oxygen levels and those propagated under reduced oxygen levels. Cells propagated using lower oxygen concentrations showed earlier cell growth with 40% lower final cell counts, resulting in 50% reduced biomass yields. Additionally, lower oxygen concentrations during propagation led to lower pH shifts during primary fermentation with 20% more higher alcohols and elevated formation of acetaldehyde, and esters.

Online Identification of Beer Fermentation Phases

Online Identification of Beer Fermentation Phases

Enhancing Probiotic Viability in Beer Fermentation: Selection of Stress-Resistant Lactic Acid Bacteria and Alternative Approaches

Enhancing Probiotic Viability in Beer Fermentation: Selection of Stress-Resistant Lactic Acid Bacteria and Alternative Approaches

Utilization of the Dicarbonyl Compounds 3-Deoxyglucosone and 3-Deoxymaltosone during Beer Fermentation by Saccharomyces Yeasts

In beer production, 1,2-dicarbonyl compounds such as 3-deoxyglucosone (3-DG) and 3-deoxymaltosone (3-DM) are formed via Maillard reaction or caramelization especially during malt kilning or wort boiling, resulting in substantial concentrations in wort. Consequences of dicarbonyl compounds for yeast metabolism are widely unknown. In the present study, the handling of 3-DG and 3-DM by Saccharomyces strains from different habitats in wort and during beer fermentation was investigated. We show that beer yeast strains induced a faster 3-DG degradation in Pilsner wort and were additionally more stress-resistant to 3-DG compared to yeasts isolated from natural habitats. In fermentation experiments comparing a light wort and a dark wort prepared from malt extracts, it could be shown that high levels of 3-DM in dark wort influence the utilization of 3-DG by yeasts, and thus higher levels of 3-DG remain in the wort. Beer yeast strains showed an increased formation of 3-deoxyfructose (3-DF) with up to 220 µM, which is possibly due to a preferred metabolization of 3-DM, as indicated by the low degradation rate of 3-DG. In contrast, yeasts isolated from natural habitats produced significantly lower amounts of 3-DF. This suggests an adaptation of technologically used yeasts to metabolization of dicarbonyl compounds, possibly as a result of beer yeast domestication.

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.

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.

Temperature control of beer fermentation based on variable domain fuzzy PID and neural network technology and its application analysis

AbstractTemperature control in the beer manufacturing process is crucial for product quality. Given the gap between China's automation in beer production and the international level, improving the technology in this area has gradually become a core issue in optimizing domestic beer production. This study combines a proportional integral derivative controller with a fuzzy modeling strategy and incorporates a variable‐domain structure to propose a variable‐domain fuzzy proportional integral derivative controller control method. To cope with the challenges of production interaction, the study also introduces neural network technology. The experimental data indicated that the variable‐domain fuzzy proportional integral derivative controller outperforms the conventional proportional integral derivative controller and the fuzzy proportional integral differential controller in terms of overshooting, with a maximum overshoot of only 1.0, compared with 0.50 and 0.70, respectively. The variable‐domain fuzzy proportional integral differential controller exhibited a minimal overshoot of only 0.01 when the model parameter is increased by 20%. In comparison, the other methods reach overshoot values of 0.92 and 1.0. The proposed method maintained superior stability even under the influence of impulse disturbance, step disturbance, and modeling variations. These results demonstrated that the research method is significantly more stable than both the proportion integration differentiation (PID) controller and fuzzy PID controller in complex dynamic parameter environments. The proposed method involved 60 rounds of neural network control, which was successfully implemented. The temperature readings T1 and T2 remained stable within the range of 1.0%–1.02% throughout the experiments. The study demonstrates that the proposed methods have higher accuracy and less fluctuation in actual application, making them more available. Taken together, the above results show that the combination of variable‐domain fuzzy PID controller and neural network technology in beer production has achieved excellent control results. This study not only provides a strong technical support for the progress of beer production technology in China, but also has important industrial application value and wide promotion prospects.

Hi-C metagenomics facilitate comparative genome analysis of bacteria and yeast from spontaneous beer and cider

Sequence-based analysis of fermented foods and beverages' microbiomes offers insights into their impact on taste and consumer health. High-throughput metagenomics provide detailed taxonomic and functional community profiling, but bacterial and yeast genome reconstruction and mobile genetic elements tracking are to be improved.We established a pipeline for exploring fermented foods microbiomes using metagenomics coupled with chromosome conformation capture (Hi-C metagenomics). The approach was applied to analyze a collection of spontaneously fermented beers and ciders (n = 12). The Hi-C reads were used to reconstruct the metagenome-assembled genomes (MAGs) of bacteria and yeasts facilitating subsequent comparative genomic analysis, assembly scaffolding and exploration of “plasmid-bacteria” links. For a subset of beverages, yeasts were isolated and characterized phenotypically.The reconstructed Hi-C MAGs primarily belonged to the Lactobacillaceae family in beers, along with Acetobacteraceae and Enterobacteriaceae in ciders, exhibiting improved quality compared to conventional metagenomic MAGs. Comparative genomic analysis of Lactobacillaceae Hi-C MAGs revealed clustering by niche and suggested genetic determinants of survival and probiotic potential. For Pediococcus damnosus, Hi-C-based networks of contigs enabled linking bacteria with plasmids. Analyzing phylogeny and accessory genes in the context of known reference genomes offered insights into the niche specialization of beer lactobacilli. The subspecies-level diversity of cider Tatumella spp. was disentangled using a Hi-C-based graph. We obtained highly complete yeast Hi-C MAGs primarily represented by Brettanomyces and Saccharomyces, with Hi-C-facilitated chromosome-level genome assembly for the former.Utilizing Hi-C metagenomics to unravel the genomic content of individual species can provide a deeper understanding of the ecological interactions within the food microbiome, aid in bioprospecting beneficial microorganisms, improving quality control and improving innovative fermented products.

Transcriptional Analysis of Mixed-Culture Fermentation of Lachancea thermotolerans and Saccharomyces cerevisiae for Natural Fruity Sour Beer

Increasingly high interest in yeast–yeast interactions in mixed-culture fermentation is seen along with beer consumers’ demands driving both market growth and requests for biotechnological solutions that can provide better sensory characteristics. In this study, Lachancea thermotolerans and Saccharomyces cerevisiae with a cell population ratio of 10:1 were inoculated for sour beer fermentation while the process conditions within the brewing industry remained unchanged. With L. thermotolerans producing lactic acid (1.5–1.8 g/L) and bringing down the pH to 3.3–3.4 whilst adding no foreign flavors herein, this study revealed a new natural, fruity sour beer with a soft, sour taste. In this study, the double-yeast mixed-culture fermentation produced more flavor substances than a single-culture process, and plenty of isobutyl acetate and isoamyl acetate enhanced the fruit aroma and balanced the sour beer with a refreshing taste. While playing a positive role in improving the beer’s quality, the double-yeast mixed-culture fermentation developed in this study helps to offer an alternative mass production solution for producing sour beer with the processes better controlled and the fermentation time reduced. The stress responses of the L. thermotolerans during the fermentation were revealed by integrating RNA sequencing (RNA-Seq) and metabolite data. Given that the metabolic flux distribution of the S. cerevisiae during the fermentation differed from that of the non-Saccharomyces yeasts, transcriptional analysis of non-Saccharomyces yeast and S. cerevisiae could be suitable in helping to develop strategies to modulate the transcriptional responses of specific genes that are associated with the aroma compounds released by S. cerevisiae and non-Saccharomyces yeasts. In the case of some non-Saccharomyces yeast species/strains, the diversion of alcoholic fermentation and the formation of a great number of secondary compounds may, in part, account for the low ethanol yield.

Review: Continuous fermentation of beer

This work reflects the basic information currently known regarding continuous fermentation and post-fermentation of beer. The history of continuous fermentation since the first documented mention of the technology is examined. A comparison is made of foreign and domestic continuous fermentation technologies. The prospect of eliminating the shortcomings of this method - the complexity of operation and high cost of equipment - is being considered. The issues of continuous brewing of beer are touched upon. With the advent of immobilized yeast, the process has become more accessible to master. Such yeast has a number of advantages, especially interesting for a continuous process - fermentation time is reduced and the useful life of the yeast is increased. As a result, a smaller quantity of yeast can be used for the process, which reduces the size of the yeast colony and reduces equipment costs (since comparatively more yeast is required for a continuous process). The possibility of using brewer's grains, a by-product of production, as a carrier reagent for immobilized yeast is highlighted, which will reduce the cost of production. Yeast spontaneously adheres to the surface of such a carrier, which leads to direct contact of the immobilized mass with liquid substrates. We came to the conclusion that beer prepared using continuous fermentation does not differ in organoleptic properties from beer prepared using classical technology. Despite the fact that at present continuous fermentation is practically not covered, the materials of the article show that further research in this area is extremely promising and in demand, as it will speed up the time of beer production, as well as make the process more ergonomic.

Residual brewer’s Saccharomyces cerevisiae yeasts as biofertilizers in horticultural seedlings: towards a sustainable industry and agriculture

The food industry generates substantial amounts of organic waste often underutilized within the system. Craft beer production, experiencing global rapid expansion, contributes to this waste stream with byproducts such as spent grain, trub, and yeast. Many craft beer industries discharge yeast residue directly into public water bodies. In recent years, yeasts have garnered attention for their potential to enhance plant growth and contribute to sustainable agriculture. This study focuses on characterizing Saccharomyces cerevisiae yeast collected at the end of the craft beer fermentation process. Biomass characterization was conducted, and the yeast’s effect on lettuce and tomato seeds and seedlings was evaluated at four concentrations (105, 106, 107, and 108 cells mL−1) in sterile substrate. After 28 days, plant height, leaf number, fresh and dry weights of both aboveground and root parts, as well as chlorophyll content, were analyzed. The most effective concentration (107 cells mL−1) was applied to tomato seedlings in sterile substrate, compared with a commercial organic fertilizer. After 21 days, growth parameters were assessed. The study demonstrated that increasing yeast doses up to 108 cells mL−1 positively affects seed germination and seedling development. Notably, a dose of 107 cells mL−1 proved effective for application in seedlings as an organic amendment and substitute for commercial products. This integrated approach showcases the potential of yeasts in sustainable agriculture, utilizing byproducts from the food industry to enhance crop performance and mitigate environmental pollution.

From Data to Draught: Modelling and Predicting Mixed-Culture Beer Fermentation Dynamics Using Autoregressive Recurrent Neural Networks

The ascendency of the craft beer movement within the brewing industry may be attributed to its commitment to unique flavours and innovative styles. Mixed-culture fermentation, celebrated for its novel organoleptic profiles, presents a modelling challenge due to its complex microbial dynamics. This study addresses the inherent complexity of modelling mixed-culture beer fermentation while acknowledging the condition monitoring limitations of craft breweries, namely sporadic offline sampling rates and limited available measurement parameters. A data-driven solution is proposed, utilising an Autoregressive Recurrent Neural Network (AR-RNN) to facilitate the production of novel, replicable, mixed-culture fermented beers. This research identifies time from pitch, specific gravity, pH, and fluid temperature as pivotal model parameters that are cost-effective for craft breweries to monitor offline. Notably, the autoregressive RNN fermentation model is generated using high-frequency multivariate data, a departure from intermittent offline measurements. Employing the trained autoregressive RNN framework, we demonstrate its robust forecasting prowess using limited offline input data, emphasising its ability to capture intricate fermentation dynamics. This data-driven approach offers significant advantages, showcasing the model’s accuracy across various fermentation configurations. Moreover, tailoring the design to the craft beer market’s unique demands significantly enhances the model’s practicable predictive capabilities. It empowers nuanced decision-making in real-world mixed-culture beer production. Furthermore, this model lays the groundwork for future studies, highlighting transformative possibilities for cost-effective model-based control systems in the craft beer sector.

Fermentation of a Strong Dark Ale Hybrid Beer Enriched with Carob (Ceratonia siliqua L.) Syrup with Enhanced Polyphenol Profile

There is an increasing trend to develop beers supplemented with local plant ingredients in order to increase their bioactivity. Carob (Ceratonia siliqua L.) is a xerophytic endemic tree typically found in Mediterranean ecosystems. The aim of this study was to develop a strong dark ale hybrid beer enriched with carob syrup prepared by using carob fruits from the University Campus (Athens, Greece). Three batches of beer were fermented, a dark ale (6% alcohol by volume or ABV) without carob and two strong dark ale beers (8% and 10% ABV) with carob syrup. After the second fermentation (bottle conditioning, 60 days), both carob beers had significantly increased bioactivity. The total phenolic content (176.4 mg GAE/100 mL), the antiradical activity (206.6 mg Trolox Equivalent (TE)/100 mL), and the antioxidant activity (838.2 mg Fe2+/100 mL) of the carob strong dark ale 10% ABV beer was increased by more than three times, six times, and eight times, respectively, compared to the standard dark ale (6% ABV) without carob. Moreover, LC-QToF-MS analysis ascertained the enhancement of the phenolic profile of carob beers by ten phenolic compounds compared to the control dark ale beer without carob, indicating their significant antioxidant activity.

Effect of cherry products addition on beer fermentation

Fruits has been used in brewing as a source of sugars, colour and flavour. Cherry (Prunus avium L.) products such as juice and pomace can be used in brewing in order to increase beer biological value. In this study, cherry juice and pomace in concentration of 15 % were added at first and seventh day of beer fermentation. The effect of cherry products addition was investigated by measuring the content of yeast metabolites (ethanol, aldehydes, higher alcohols, esters, and vicinal diketones) in cherry beers and control sample without cherries. The alcohol content in all the cherry beers was higher than the control sample. The cherry juice addition at the beginning of fermentation led to the formation of more secondary metabolites than the control. Cherry juice addition at the seventh day of fermentation resulted in a decrease in higher alcohols and esters concentration, but in an increase in carbonyls concentration compared to the control. Cherry pomace addition led to a significant increase in esters and vicinal diketones concentration. Aldehydes concentration was not affected by cherry pomace addition. Higher alcohols were influenced only by pomace addition at the seventh day of fermentation. Sensory evaluation was also made because yeast metabolites affected beer flavour and aroma.