Acidic Beer Research Articles

Survival of the probiotic strain Lacticaseibacillus paracasei subsp. paracasei F19 in high-hopped beers

This study aims to enhance understanding of probiotic lactic acid bacteria (LAB) survival in high-hopped beer formulations and their interactions with different yeasts and highlights the fermentation processes, microbial metabolism, and production of distinctive beer flavors. For this, this research used Lacticaseibacillus paracasei F19 (F19), Saccharomycodes ludwigii, and Saccharomyces cerevisiae strains US-05 (US-05) and Kveik (Kveik) for brewing. Bacterial and yeast cultures were prepared, fermented in wort, and analyzed in different hop concentrations (International Bitterness Units − IBU 0, 20, 40). Methods included physicochemical analysis, yeast and bacterial counts, RT-qPCR for gene expression, statistical analysis, and sensory evaluation by sommeliers following BJCP guidelines. Physicochemical analysis showed efficient fermentation across all hop concentrations (IBU 0, 20, 40), with decreasing SG and pH over time due to lactic acid bacteria and yeast metabolism. Higher hop levels (IBU 20 and 40) resulted in less acidic beer, indicating hop interference with bacterial activity. Yeast populations remained stable regardless of hop content, with Saccharomyces cerevisiae and Saccharomycodes ludwigii performing well. Probiotic strain F19 exhibited robust viability in all formulations. Sensory analysis favored higher hop content beers, suggesting consumer acceptance and potential health benefits of probiotic, high-hop beers. Higher hop content hindered sour beer production as only hop-free beers reached low pH levels. Probiotic strain F19 remained viable under high IBU formulations (20 and 40), with these being preferred by sommeliers using BJCP methodology. All yeast strains supported F19 survival. Further studies are needed on gastrointestinal resistance and clinical benefits.

Study on the technology of kumquat grapefruit sour beer

A kumquat-grapefruit acid beer was brewed with Australian barley malt, lactobacillu, D17 yeast, Qingdao hop flower, kumquat concentrated juice and grapefruit concentrated juice as raw materials by using special mash and fermentation process. The effects of acidification degree, the addition amount of kumquat and grapefruit juice concentrate and the addition time on beer flavor were studied in this paper. The results showed that when the pH was adjusted to 3.5 by acidification, the sour beer produced by adding 6% kumquat concentrated juice and 4% grapefruit concentrated juice before the CO2 pressure of the tank rised, the beer has white and exquisite foam with prominent fruit aroma, especially those of kumquat and grapefruit. The beer body was clear and transparent, with about 5% residual sugar. The sweet and sour taste of the beer was balanced. The beer contained unique nutrients of kumquat and grapefruit also, and was especially suitable to drink for brewers and ladies.

The ancient Egyptian bread and fermentation

The use of yeast to leaven bread by the production of carbon dioxide was developed in Egypt. The ancient Egyptians extended their bread-making technology to the production of an acidic beer called boza or boozah from a lightly baked loaf' of germinated grain.

Microbial acidification, alcoholization, and aroma production during spontaneous lambic beer production.

Acidic beers, such as Belgian lambic beers and American and other coolship ales, are becoming increasingly popular worldwide thanks to their refreshing acidity and fruity notes. The traditional fermentation used to produce them does not apply pure yeast cultures but relies on spontaneous, environmental inoculation. The fermentation and maturation process is carried out in wooden barrels and can take up to three years. It is characterized by different microbial species belonging to the enterobacteria, acetic acid bacteria, lactic acid bacteria, and yeasts. This review provides an introduction to the technology and four fermentation strategies of beer production, followed by the microbiology of acidic beer production, focusing on the main microorganisms present during the long process used for the production of Belgian lambic beers. © 2018 Society of Chemical Industry.

Recipe, volatiles profile, sensory analysis, physico-chemical and microbial characterization of acidic beers from both sourdough yeasts and lactic acid bacteria

The study focused on the recipe optimization, production, physico-chemical and sensory characterization of sourdough beer and their comparison to commercial beers. For the first time the whole sourdough microbiota (not only yeasts but also lactic acid bacteria) was used as a starter. The microbiota was not isolated, the starter was a practical suspension of sourdough in water. The changes of gravity, pH, fermentation rate, and microbial counts during fermentation were rationalized on the basis of microbial metabolism. The initial prevalence of lactic acid bacteria evolves to a predominance of yeasts with a minimum pH. The reduction of gravity and pH is correlated to the oxidative sugar consumption and production of organic acids and carbon dioxide. The samples’ volatile profile, crucial from a commercial point of view, was described. The most abundant volatiles are esters and alcohols. Ketones, aldehydes, and hydrocarbons are present to a lower extent. Vicinal diketones, responsible for beer off-flavor, and hydrocarbons are only present in sourdough samples but not in the corresponding beer samples or in commercial beer. A comparison between the volatile fingerprints of an acidic beer and that of the corresponding sourdough was performed. The former is simpler that the latter. Acidic beers are characterized by the presence of ethyl butanoate and ethyl decanoate. A beer judge described beer sensory attributes. Principal component analysis and clustering analysis enabled the discrimination among sourdough, acidic beer and commercial beer. The industrial scale-up of this process is desirable because there is an increasing worldwide consumption of specialty beer.

Temporal and Spatial Distribution of the Acetic Acid Bacterium Communities throughout the Wooden Casks Used for the Fermentation and Maturation of Lambic Beer Underlines Their Functional Role.

Few data have been published on the occurrence and functional role of acetic acid bacteria (AAB) in lambic beer production processes, mainly due to their difficult recovery and possibly unknown role. Therefore, a novel aseptic sampling method, spanning both the spatial and temporal distributions of the AAB and their substrates and metabolites, was combined with a highly selective medium and matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) as a high-throughput dereplication method followed by comparative gene sequencing for their isolation and identification, respectively. The AAB (Acetobacter species more than Gluconobacter species) proliferated during two phases of the lambic beer production process, represented by Acetobacter orientalis during a few days in the beginning of the fermentation and Acetobacter pasteurianus from 7 weeks until 24 months of maturation. Competitive exclusion tests combined with comparative genomic analysis of all genomes of strains of both species available disclosed possible reasons for this successive dominance. The spatial analysis revealed that significantly higher concentrations of acetic acid (from ethanol) and acetoin (from lactic acid) were produced at the tops of the casks, due to higher AAB counts and a higher metabolic activity of the AAB species at the air/liquid interface during the first 6 months of lambic beer production. In contrast, no differences in AAB species diversity occurred throughout the casks.IMPORTANCE Lambic beer is an acidic beer that is the result of a spontaneous fermentation and maturation process. Acidic beers are currently attracting attention worldwide. Part of the acidity of these beers is caused by acetic acid bacteria (AAB). However, due to their difficult recovery, they were never investigated extensively regarding their occurrence, species diversity, and functional role in lambic beer production. In the present study, a framework was developed for their isolation and identification using a novel aseptic sampling method in combination with matrix-assisted laser desorption ionization-time of flight mass spectrometry as a high-throughput dereplication technique followed by accurate molecular identification. The sampling method applied enabled us to take spatial differences into account regarding both enumerations and metabolite production. In this way, it was shown that more AAB were present and more acetic acid was produced at the air/liquid interface during a major part of the lambic beer production process. Also, two different AAB species were encountered, namely, Acetobacter orientalis at the beginning and Acetobacter pasteurianus in a later stage of the production process. This developed framework could also be applied for other fermentation processes.

Intensification of beveragement processes by enzymes of enzymes

Beer is a complex colloidal system. The appearance of turbidity during storage of beer is due to an increase in the size of particles due to their collision, condensation (oxidation) and polymerization. The cause of turbidity in fresh beer, when it is cooled, is the interconnection of low molecular weight phenolic compounds with acidic beer proteins. To improve the colloidal stability of beer, enzyme preparations containing cytolytic, proteolytic and amylolytic enzymes used in the preparation of wort are used. Most of the drugs used for brewing are complex. The possibility of using Viscoferm enzymes at the fermentation stage has been established. The mechanism of the effect is also studied. The purpose of the determination of the enzyme and halothane is the destruction of the bond between proteins and high molecular weight phenolic compounds, which are bonded by proteins not only with hydrogen bonds, but also by hydrophobic and ionic bonds and do not decay when heated. Studies have shown that Viscoferm with a concentration of 0.02 g / dl best influences the stability of beer.

Terminal acidic shock inhibits sour beer bottle conditioning by Saccharomyces cerevisiae

During beer fermentation, the brewer's yeast Saccharomyces cerevisiae experiences a variety of shifting growth conditions, culminating in a low-oxygen, low-nutrient, high-ethanol, acidic environment. In beers that are bottle conditioned (i.e., carbonated in the bottle by supplying yeast with a small amount of sugar to metabolize into CO2), the S. cerevisiae cells must overcome these stressors to perform the ultimate act in beer production. However, medium shock caused by any of these variables can slow, stall, or even kill the yeast, resulting in production delays and economic losses. Here, we describe a medium shock caused by high lactic acid levels in an American sour beer, which we refer to as “terminal acidic shock”. Yeast exposed to this shock failed to bottle condition the beer, though they remained viable. The effects of low pH/high [lactic acid] conditions on the growth of six different brewing strains of S. cerevisiae were characterized, and we developed a method to adapt the yeast to growth in acidic beer, enabling proper bottle conditioning. Our findings will aid in the production of sour-style beers, a trending category in the American craft beer scene.

Comparative genome analysis of Pediococcus damnosus LMG 28219, a strain well-adapted to the beer environment.

BackgroundPediococcus damnosus LMG 28219 is a lactic acid bacterium dominating the maturation phase of Flemish acid beer productions. It proved to be capable of growing in beer, thereby resisting this environment, which is unfavorable for microbial growth. The molecular mechanisms underlying its metabolic capabilities and niche adaptations were unknown up to now. In the present study, whole-genome sequencing and comparative genome analysis were used to investigate this strain’s mechanisms to reside in the beer niche, with special focus on not only stress and hop resistances but also folate biosynthesis and exopolysaccharide (EPS) production.ResultsThe draft genome sequence of P. damnosus LMG 28219 harbored 183 contigs, including an intact prophage region and several coding sequences involved in plasmid replication. The annotation of 2178 coding sequences revealed the presence of many transporters and transcriptional regulators and several genes involved in oxidative stress response, hop resistance, de novo folate biosynthesis, and EPS production. Comparative genome analysis of P. damnosus LMG 28219 with Pediococcus claussenii ATCC BAA-344T (beer origin) and Pediococcus pentosaceus ATCC 25745 (plant origin) revealed that various hop resistance genes and genes involved in de novo folate biosynthesis were unique to the strains isolated from beer. This contrasted with the genes related to osmotic stress responses, which were shared between the strains compared. Furthermore, transcriptional regulators were enriched in the genomes of bacteria capable of growth in beer, suggesting that those cause rapid up- or down-regulation of gene expression.ConclusionsGenome sequence analysis of P. damnosus LMG 28219 provided insights into the underlying mechanisms of its adaptation to the beer niche. The results presented will enable analysis of the transcriptome and proteome of P. damnosus LMG 28219, which will result in additional knowledge on its metabolic activities.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-015-1438-z) contains supplementary material, which is available to authorized users.

Determination of Tyrosine and Tryptophan by Sequential Injection Analysis and Chemiluminescence Detection

A sequential injection procedure with chemiluminescence detection was developed for the determination of tyrosine and tryptophan without chromatographic separation. Two reaction systems were included in this method; one is based on the inhibition of tyrosine and tryptophan to the chemiluminescence reaction of cerium (IV)–quinine–cysteine; the other is grounded on the enhancement of tryptophan to the chemiluminescence reaction of cerium (IV)–Tween40. The two reaction systems were integrated by two syringe pumps and a multiposition valve, and they were separated by an air column to avoid interferences. The procedure was applied to the determination of tyrosine and tryptophan in an amino acid injection, beer, milk, and soybean milk.

Direct spectrophotometric determination of cerium sub-group rare earth elements with m-trifluoromethylchlorophosphonazo in the presence of ytrrium sub-group elements in nodular cast iron and steel samples

Direct spectrophotometric determination of cerium sub-group rare earth elements with m-trifluoromethylchlorophosphonazo in the presence of ytrrium sub-group elements in nodular cast iron and steel samples