Sour Beer Research Articles

Sake Brewing and Bacteria Inhabiting Sake Breweries.

Sake is a Japanese traditional fermented alcoholic drink. It is brewed using koji mold to convert the starch in rice into sugar, which is then converted into ethanol by sake yeast. Two eukaryotic microorganisms, Aspergillus oryzae and Saccharomyces cerevisiae, are used for sake brewing, leading to highly efficient ethanol fermentation. The final ethanol concentration is ~20%, which is higher than that of beer and wine. The use of technology in the sake brewing process is remarkably high and involves parallel double fermentation. In contrast, beer is brewed using malt to convert the starch in barley into sugar, which is then converted into ethanol by beer yeast. In winemaking, wine yeast converts sugar from grapes into ethanol. Beer and wine processes can include also serial yeast-based double fermentation. It is well-known that bacteria, mainly lactic acid bacteria, can have a role in the production process of beer (sour beer) and wine (malolactic fermentation) (Berbegal et al., 2019; De Roos et al., 2020; Dysvik et al., 2020; Virdis et al., 2020). On the opposite, several alcoholic beverages, such as sake, are considered fermented only by eukaryotic microorganisms. Beer, sake, and wine originated long before the discovery of microorganisms. Thus, these alcoholic drinks were produced without understanding the mechanism of ethanol fermentation. Surprisingly, sake undergoes pasteurization, called hiire, in the process of sake storage, and it has been recorded as performed 300 years before Pasteur reported the pasteurization method. The high level of biotechnology involved in sake brewing has been maintained for a long time. Sake breweries are widely distributed in Japan, and there may be much more to learn from the sake brewing process. Sake has different grades depending on the degree of polishing of rice. The highest grade (Daiginjo) is produced using polished rice with 50% or more removal of the outer layer of the grain. In addition, sake is distinguished by the addition of distilled alcohol. Sake without distilled alcohol is called Junmaishu. This opinion paper proposes Sake as a model matrix to highlight bacterial role in traditional beverages that are considered exclusively mold/yeast-based. In addition, the opinion underlines the importance of considering all microbial determinants for a complete safety assessment.

Craft Beers Fermented by Potential Probiotic Yeast or Lacticaseibacilli Strains Promote Antidepressant-Like Behavior in Swiss Webster Mice.

This study aimed to produce a probiotic-containing functional wheat beer (PWB) by an axenic culture system with potential probiotic Saccharomyces cerevisiae var boulardii 17 and probiotic-containing functional sour beer (PSB) by a semi-separated co-cultivation system with potential probiotic Lacticaseibacillus paracasei DTA 81 and Saccharomyces cerevisiae S-04. Additionally, results obtained from in vivo behavioral tests with Swiss Webster mice treated with PWB or PSB were provided, which is scarce in the current literature. Although the use of S. boulardii to produce beers is not a novelty, this study demonstrated that S. boulardii 17 performance on sugar wort stills not completely elucidated; therefore, further studies should be considered before using the strain in industrial-scale production. Co-culture systems with lacticaseibacilli strain and S. cerevisiae have been reported in the literature for PSB production. However, lacticaseibacilli survivability in beer can be improved by semi-separated co-cultivation systems, highlighting the importance of growing lacticaseibacilli in the wort before yeast pitching. Besides, kettle hopping must be chosen as the method for hop addition to produce PSB. The dry-hopping method may prevent iso-alpha formation in the wort; however, a tendency to sediment can drag cells at the tank bottom and negatively affect L. paracasei DTA 81 viability. Despite stress factors from the matrices and the stressful conditions encountered during GI transit, potential probiotic S. boulardii 17 and potential probiotic L. paracasei DTA 81 withstood at sufficient doses to promote antidepressant effects in the mice group treated with PWB or PSB, respectively.

Description of the temporal dynamics in microbial community composition and beer chemistry in sour beer production via barrel ageing of finished beers

Currently, there is a strong interest in barrel ageing of finished, conventionally fermented beers, as a novel way to produce sour beers with a rich and complex flavour profile. The production process, however, remains largely a process of trial and error, often resulting in profit losses and inconsistency in quality. To improve product quality and consistency, a better understanding of the interactions between microorganisms, wood and maturing beer is needed. The aim of this study was to describe the temporal dynamics in microbial community composition, beer chemistry and sensory characteristics during barrel ageing of three conventionally fermented beers that differed in parameters like alcohol content and bitterness. Beers were matured for 38 weeks in new (two types of wood) and used (one type of wood) oak barrels. Beer samples were taken at the start of the maturation and after 2, 12 and 38 weeks. Microbial community composition, determined using amplicon sequencing of the V4 region of the bacterial 16S rRNA gene and the fungal ITS1 region, beer chemistry and sensory characteristics substantially changed throughout the maturation process. Likewise, total bacterial and fungal population densities generally increased during maturation. PerMANOVA revealed significant differences in the bacterial and fungal community composition of the three beers and across time points, but not between the different wood types. By contrast, significant differences in beer chemistry were found across the different beers, wood types and sampling points. Results also indicated that the outcome of the maturation process likely depends on the initial beer properties. Specifically, results suggested that beer bitterness may restrain the bacterial community composition, thereby having an impact on beer souring. While the bacterial community composition of moderately-hopped beers shifted to a dominance of lactic acid bacteria, the bacterial community of the high-bitterness beer remained fairly constant, with low population densities. Bacterial community composition of the moderate-bitterness beers also resembled those of traditional sours like lambic beers, hosting typical lambic brewing species like Pediococcus damnosus, Lactobacillus brevis and Acetobacter sp. Furthermore, results suggested that alcohol level may have affected the fungal community composition and extraction of wood compounds. More specifically, the concentration of wood compounds like cis-3-methyl-4-octanolide, trans-3-methyl-4-octanolide, eugenol and total polyphenols was higher in beers with a high alcohol content. Altogether, our results provide novel insights into the barrel ageing process of beer, and may pave the way for a new generation of sour beers.

Chemical Composition of Sour Beer Resulting from Supplementation the Fermentation Medium with Magnesium and Zinc Ions.

The bioavailability of minerals, such as zinc and magnesium, has a significant impact on the fermentation process. These metal ions are known to influence the growth and metabolic activity of yeast, but there are few reports on their effects on lactic acid bacteria (LAB) metabolism during sour brewing. This study aimed to evaluate the influence of magnesium and zinc ions on the metabolism of Lactobacillus brevis WLP672 during the fermentation of brewers’ wort. We carried out lactic acid fermentations using wort with different mineral compositions: without supplementation; supplemented with magnesium at 60 mg/L and 120 mg/L; and supplemented with zinc at 0.4 mg/L and 2 mg/L. The concentration of organic acids, pH of the wort and carbohydrate use was determined during fermentation, while aroma compounds, real extract and ethanol were measured after the mixed fermentation. The addition of magnesium ions resulted in the pH of the fermenting wort decreasing more quickly, an increase in the level of L-lactic acid (after 48 h of fermentation) and increased concentrations of some volatile compounds. While zinc supplementation had a negative impact on the L. brevis strain, resulting in a decrease in the L-lactic acid content and a higher pH in the beer. We conclude that zinc supplementation is not recommended in sour beer production using L. brevis WLP672.

Use of probiotic strains to produce beers by axenic or semi-separated co-culture system

This study evaluated the production of beers to serve as matrices for probiotic delivery and designed suitable fermentation systems. Two types of beers (wheat and sour) were produced by fermentation in an axenic (Saccharomyces cerevisiae var boulardii 17) or semi-separated co-culture system (Lacticaseibacillus paracasei DTA-81 and Saccharomyces cerevisiae S-04). Firstly, trial was carried out to investigate microbial interactions between L. paracasei DTA-81 and Saccharomyces (n = 4) and to determine the best cultivation system to produce sour beer. S. boulardii17 potential to ferment the beer wort was similar to those observed for other brewer yeasts, enabling potentially probiotic wheat beer production. L. paracaseiDTA-81 was able to ferment the beer wort to produce potentially probiotic sour beer. However, the cultivation system should be carefully designed to protect the lacticaseibacilli from stressful metabolites produced during yeast fermentation, especially alcohol. Thus, data obtained herein showed that the co-culture system should be avoided for potentially probiotic sour beer production, in order to prevent competitive interaction between lacticaseibacilli and yeast. Otherwise, the semi-separated co-culture system resulted in a symbiotic commensal interaction, without interfering on L. paracasei DTA-81 growth and survivability. Therefore, wheat and sour beers can be highlighted as useful matrices to deliver probiotic strains.

A novel image cytometry-based Lactobacillus bacterial enumeration method for the production of kettle sour beer

The demands for a variety of craft beer flavors have been increasing in the United States. To meet this rising demand, breweries have been experimenting with kettle sour beer that utilizes lactic acid-producing bacteria for fermentation. The current standard bacterial quantification method is insufficient for rigorous quality control, thus there is a need for a better method to monitor lactobacilli concentration in a kettle sour environment. In this work, an automated Lactobacillus counting method was developed using fluorescence-based image cytometry. Three commonly used species were cultured, the concentrations were measured using image cytometry and evaluated against the standard spread-plating method. This procedure was undertaken in vitro at different dilutions and the method was repeated with two species in a kettle sour environment at different time points. Both the in vitro and fermentation experiments were repeated three times. Results demonstrated that the new method was not significantly different when compared to the standard plating method in either controlled settings or within the kettle sour fermentation. The proposed method provides a rapid tool to monitor and control lactobacilli growth in kettle sour beer production, and allows for standardization of the products due to the availability of near instantaneous information for quality control.

Microbial Dynamics in Traditional and Modern Sour Beer Production.

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

Seeing sweet and choosing sour: Compensatory effects of typeface on consumers’ choice behavior

The present research included two field studies investigating, firstly, the effects of round and angular typefaces on taste expectations and, secondly, how such expectations may have downstream effects on naturalistic consumer choice. A taste experiment conducted at a science festival asked participants (N = 125) to rate the expected and actual sweetness and sourness of beer served from plastic cups labelled with either angular or round typeface. Effects of typeface were found on both taste expectations and perceived taste, but in opposite directions; participants rated the expected sourness of a beer as higher in the round (vs. angular) typeface condition, whereas they rated perceived sourness as lower in the round compared to the angular typeface condition. A follow-up field study conducted at a beer bar tested whether different typefaces on a beer board would affect actual beer choices. Data consisted of beer transactions (N = 1,952) and included the monetary amount, and the specific style, and size of beer purchased. The results showed that average transaction amount was lower in the round (vs. angular) typeface condition, and that customers purchased more sour beer options in this condition. These findings support a crossmodal compensation account, and suggest that round typefaces could increase choices of contrasting sour products. Hence, marketers may want to consider how typefaces can either enhance or diminish certain tastes.

Co-fermentation Involving Saccharomyces cerevisiae and Lactobacillus Species Tolerant to Brewing-Related Stress Factors for Controlled and Rapid Production of Sour Beer.

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

Secondary Lactic Acid Bacteria Fermentation with Wood-Derived Xylooligosaccharides as a Tool To Expedite Sour Beer Production.

Xylooligosaccharides (XOS) from woody biomass were evaluated as a substrate for secondary lactic acid bacteria (LAB) fermentation in sour beer production. XOS were extracted from birch (Betula pubescens) and added to beer to promote the growth of Lactobacillus brevis BSO 464. Growth, pH, XOS degradation, and metabolic products were monitored throughout fermentations, and the final beer was evaluated sensorically. XOS were utilized, metabolic compounds were produced (1800 mg/L lactic acid), and pH was reduced from 4.1 to 3.6. Secondary fermentation changed sensory properties significantly, and the resulting sour beer was assessed as similar to a commercial reference in multiple attributes, including acidic taste. Overall, secondary LAB fermentation induced by wood-derived XOS provided a new approach to successfully produce sour beer with reduced fermentation time (from 1-3 years to 4 weeks). The presented results demonstrate how hemicellulosic biomass can be valorized for beverage production and to obtain sour beer with improved process control.

Characteristics of Cornelian cherry sour non-alcoholic beers brewed with the special yeast Saccharomycodes ludwigii

Recipes for traditional and sour non-alcoholic beers were developed in this study employing a special yeast species Saccharomycodes ludwigii. They were characterized for their basic physicochemical properties, antioxidative activity as well as subjected to the quantitative and qualitative analysis of their biologically-active compounds, and to the sensory assessment. Sour non-alcoholic beers were brewed with the addition of juice from fruits of red-colored Cornelian cherry (Cornus mas L.) variety, which are characterized by naturally sour taste and aroma. Ethyl alcohol content in the beers manufactured ranged from 0.41%v/v in traditional non-alcoholic beers to 0.43%v/v in sour non-alcoholic beers. The final products had a low energy value, ranging from 116 to 148 kcal/500 mL of beer. The sour beers had several times higher antioxidative potential and significantly higher polyphenols concentration compared to the control ones. In addition, they were rich in anthocyanins and iridoids, and presented novel sensory attributes.

Sour beer production: impact of pitching sequence of yeast and lactic acid bacteria

Sour beer production: impact of pitching sequence of yeast and lactic acid bacteria

British beer styles. Where are they heading?

PurposeThe purpose of this paper is to analyse data from routine quality control samples of beer over a ten year period to provide comparisons with a previous study in 2006 and apply interpretations to the contemporary beer market.Design/methodology/approachData from laboratory analysis of 1,469 beers submitted for due diligence quality assurance from commercial microbreweries were analysed. Additional commercial samples were taken for analysis of sour beers and cask conditioned beers as examples of niche product areas.FindingsStyle characteristics were summarized as a reference for industry evaluation and as a basis for comparisons. Differences were noted between the characteristics found and those of a similar study in 2006. Average alcohol by volume increased by 1.2 per cent, bitterness levels increased by 6.1 per cent while colour decreased by 22 per cent. These differences suggest that standard UK beers are undergoing change. A study of sour beers indicated specific features in this recently popular style and confirmed the use of a different microbiology. Analysis of cask ales indicated some variability in quality suggesting the need for greater quality control.Research limitations/implicationsThe comparison with the previous study has limitations as the samples were not individually comparable but were from major established microbreweries and so representative of the industry. The work analysed UK beers only but will act as a base line for comparison to other markets. Moreover, the data may be relevant to other forms of market analysis seeking to identify factors associated to consumer preferences.Practical implicationsThe data presented have relevance to breweries looking to develop their portfolios and product descriptions, to the drinking public and to regulatory bodies in providing a benchmark for comparisons and for assisting in defining the recently promoted term “craft beer”.Social implicationsThe findings are relevant to beverage development and consumer education of alcoholic beverages by allowing discrimination between styles with different characteristics affecting consumer choice and when assessing styles for industrial, legislative and health research. Beers today appear to be more varied than in past decades but show lower colour and higher bitterness characteristics. As these features particularly relate to ingredients they may have implications in their contributions to diet and health.Originality/valueThe work has value in replicating the previous study to illustrate changes and trends. It presents novel data on recently popular sour beers and assesses traditional cask beer with implications for product quality.

Survival of probiotic strain Lactobacillus paracasei L26 during co-fermentation with S. cerevisiae for the development of a novel beer beverage

Amidst the rising popularity of craft beers, it would be opportune to develop a novel, unfiltered and unpasteurized sour beer with high probiotic live counts. However, as beer typically contains hop iso-α-acids that prevent the growth and survival of probiotic lactic acid bacteria, the use of suitable fermentation strategies is crucial. The growth, and survival of the probiotic bacterium, Lactobacillus paracasei L26, were assessed during a 10-day co-fermentation period with a brewer's yeast, Saccharomyces cerevisiae S-04, in unhopped wort. Isomerized hop extract was added prior to storage of the beers at 25 °C and 5 °C. During co-fermentation in unhopped wort, L. paracasei L26 maintained high viable cell counts above 8 Log CFU/mL, indicating species compatibility with the yeast. The majority of fermentable sugars were attenuated by S. cerevisiae S-04, with a concomitant production of alcohols and esters. Significant amounts of lactic acid were produced by L. paracasei L26 (P < 0.05). During storage with added isomerized hop extract, maximal probiotic viability enhancing effects were observed in the presence of live S. cerevisiae S-04, in combination with refrigeration. The results suggest that beers could be a vehicle for probiotic delivery under appropriate conditions. This was the first study demonstrating the feasibility of utilizing probiotic lactobacilli as starter cultures in beer brewing.

Leveraging endogenous barley enzymes to turn lactose-containing dairy by-products into fermentable adjuncts for Saccharomyces cerevisiae-based ethanol fermentations

Acid whey, a by-product of strained yogurt production, represents a disposal challenge for the dairy industry. Utilization schemes are currently limited; however, acid whey contains valuable components that could be used to create value-added products. One potential scheme would be the fermentation of acid whey into an alcoholic beverage. Sour beers are gaining popularity and acid whey, which is sour to begin with, could provide a new product opportunity. However, the main sugar of acid whey, lactose, cannot be fermented by the traditional brewer's yeast, Saccharomyces cerevisiae. It has been reported that barley contains enzymes capable of hydrolyzing lactose to glucose and galactose, which are fermentable by S. cerevisiae. We investigated whether a barley-based mash resulted in detectable hydrolysis of lactose into sugars fermentable by S. cerevisiae. We demonstrated the ability to hydrolyze lactose in acid whey using a barley-based mash, resulting in the average release of 3.70 g/L of glucose. Additionally, the subsequent liquid was fermented by S. cerevisiae to an average ethanol concentration of 3.23% alcohol by volume. This work demonstrates the ability to hydrolyze the lactose in acid whey using barley and the opportunity to use acid whey as a fermentable sugar source in beer production.

Sour Beer at the Boar’s Head: Salvaging Shakespeare’s Alewife, Mistress Quickly

Using William Shakespeare’s character Mistress Nell Quickly as an example, this article contends that familiarity with both the literary tradition of alewives and the historical conditions in which said literary tradition brewed aids in revising our interpretation of working-class women on the early modern stage. Mistress Quickly, the multi-faceted comic character in three history plays and a city-comedy, resembles closely those women with whom Shakespeare and his contemporaries would have lived and worked in their day-to-day lives. Rather than dismissing her role as minor or merely comic, as previous criticism largely has, scholarship can embrace this character type and her narrative as an example to complicate teleological progressions for women.

Pre-fermentation with lactic acid bacteria in sour beer production

Pre-fermentation with lactic acid bacteria in sour beer production

Primary souring: A novel bacteria-free method for sour beer production

In the beverage fermentation industry, especially at the craft or micro level, there is a movement to incorporate as many local ingredients as possible to both capture terroir and stimulate local economies. In the case of craft beer, this has traditionally only encompassed locally sourced barley, hops, and other agricultural adjuncts. The identification and use of novel yeasts in brewing lags behind. We sought to bridge this gap by bio-prospecting for wild yeasts, with a focus on the American Midwest. We isolated 284 different strains from 54 species of yeast and have begun to determine their fermentation characteristics. During this work, we found several isolates of five species that produce lactic acid and ethanol during wort fermentation: Hanseniaspora vineae, Lachancea fermentati, Lachancea thermotolerans, Schizosaccharomyces japonicus, and Wickerhamomyces anomalus. Tested representatives of these species yielded excellent attenuation, lactic acid production, and sensory characteristics, positioning them as viable alternatives to lactic acid bacteria (LAB) for the production of sour beers. Indeed, we suggest a new LAB-free paradigm for sour beer production that we term “primary souring” because the lactic acid production and resultant pH decrease occurs during primary fermentation, as opposed to kettle souring or souring via mixed culture fermentation.

Impact of buffering capacity on the acidification of wort by brewing-relevant lactic acid bacteria

Acidified wort produced biologically using lactic acid bacteria (LAB) has application during sour beer production and in breweries adhering to the German purity law (Reinheitsgebot). LAB cultures, however, suffer from end product inhibition and low pH, leading to inefficient lactic acid (LA) yields. Three brewing-relevant LAB (Pediococcus acidilactici AB39, Lactobacillus amylovorus FST2.11 and Lactobacillus plantarum FST1.7) were examined during batch fermentation of wort possessing increasing buffering capacities (BC). Bacterial growth was progressively impaired when exposed to higher LA concentrations, ceasing in the pH range of 2.9–3.4. The proteolytic rest (50°C) during mashing was found to be a major factor improving the BC of wort. Both a longer mashing profile and the addition of an external protease increased the BC (1.21 and 1.24, respectively) compared with a control wort (1.18), and a positive, linear correlation (R2 = 0.957) between free amino nitrogen and BC was established. Higher levels of BC led to significant greater LA concentration (up to +24%) after 48 h of fermentation, reaching a maximal value of 11.3 g/L. Even higher LA (maximum 12.8 g/L) could be obtained when external buffers were added to wort, while depletion of micronutrient(s) (monosaccharides, amino acids and/or other unidentified compounds) was suggested as the cause of LAB growth cessation. Overall, a significant improvement in LA production during batch fermentation of wort is possible when BC is improved through mashing and/or inclusion of additives (protease and/or external buffers), with further potential for optimization when strain-dependent nutritional requirements, e.g. sugar and amino acids, are considered. Copyright © 2017 The Institute of Brewing & Distilling

Sour Brewing: Impact of Lactobacillus Amylovorus FST2.11 on Technological and Quality Attributes of Acid Beers

This study was conducted to compare the effect of different acidification methods using Lactobacillus amylovorus FST2.11 as a starter culture on the microbiological, technological, and qualitative attributes of sour beers. Biological souring was performed in the mash after mashing, in the preboiling wort, or in the postboiling wort. This lactic acid bacterium strain was selected for its high sensitivity to hops, good growth at moderate levels of alcohol, and fast acidification in wort. Alcoholic fermentation was carried out using a commercial Saccharomyces cerevisiae (Safale US-05) strain. Desired acidification of the unhopped substrates (approximately 5–6 g/L of lactic acid) was achieved within 18 h of lactic fermentation. The lactic culture consumed maltose preferentially over monosaccharides, and uptake of free amino nitrogen was limited (8.0–12.6 mg/L). Yeast growth in soured substrates was delayed by 2–4 days compared with the unacidified control, but comparable end attenuations were achieved among all treatments. Among the soured beers, the lowest levels of off-flavors were found in preboil wort souring trials, whereas cofermented beers led to opalescent beers containing high levels of total diacetyl and acetoin. The low pH and the high level of staling compounds such as acetaldehyde suggest that sour beers suffered from low oxidative stability. Final beer qualities varied considerably depending on the souring method applied. Souring of wort by L. amylovorus FST2.11 before boiling was found to produce bright, tart beer with minor organoleptic failures while limiting the risk of bacterial cross-contamination within the brewing facility. The renewed interest that sour brewing has received among brewing communities worldwide calls for a better understanding of the advantages and disadvantages of different souring methods. The results from this study could help brewers to choose the most suitable approach according to equipment capabilities and sensorial likeness.