Search Results (7)

Consumer demand for low-alcohol acidic beers is driving the use of non-conventional yeasts in the brewing process. In this study, the addition of mixed berries and fermentation with L. thermotolerans L31 are performed in crafting a low-alcohol acidic beer. Four different beers were brewed in the primary stage with either Saccharomyces cerevisiae or L. thermotolerans and with or without added berry mixture. Beer was fermented for 8 days at 20 °C, stored, and bottled. pH, density, alcoholic content, bitterness, and color of final beer were analyzed for all samples using analytical methods. Volatile compounds, anthocyanin content, and antioxidant activity were also evaluated. Sensory analysis was performed and correlated (PCA) with the analytical results. The obtained data indicated that beers brewed with L. thermotolerans were significantly more acidic and less bitter than S. cerevisiae beers. No difference in alcoholic content was found. Fruity aroma-associated compounds were present in L. thermotolerans beers, which correlated with the sensory analysis. Fruit beers were also redder and showed higher anthocyanin content and stronger antioxidant activity due to the presence of anthocyanins such as cyanidin, delphinidin, and malvidin from fruit, and other antioxidant compounds. Full article

Beer produced by autochthonous microbial fermentation is a long-established craft beer style in Belgium that has now been implemented commercially in New Zealand. We used a metabarcoding approach to characterize the microbiome of 11 spontaneously fermented beers produced by a single brewery in Oamaru from 2016 to 2022. Key organic acid concentrations were also determined. Both bacterial and fungal populations varied considerably between vintages and between individual brews produced in 2020. Similarly, for organic acids, the concentrations of L-malic acid, succinic acid, and L-lactic acid statistically differed from one vintage to another. Moreover, a correlation between the concentrations of certain organic acids and microbial composition was inferred by ordination analyses. Through reference to publicly available climate data, humidity and maximum temperature seemed to enhance the abundance of Penicillium and Hanseniaspora in beer microbiota. However, comparison with previously published studies of Belgian lambic beers, similar Russian ales, and publicly available temperature data from these regions showed that the microbial populations of these were relatively stable despite greater extremes of weather. Our results suggest that while climatic variables may influence microbial populations during beer making that employs autochthonous fermentation in New Zealand, such variation is not evident where similar beers are produced in facilities with a long-established history of production. These findings have implications for lambic-style beer production in the context of global climate change, notably where microbial populations may lack environmental adaptation. Full article

The increasing demand for craft beer is driving the search for novel ale yeast cultures from brewing-related wild environments. The focus of bioprospecting for craft cultures is to identify feral yeasts suitable to imprint unique sensorial attributes onto the final product. Here, we integrated phylogenetic, genotypic, genetic, and metabolomic techniques to demonstrate that sour beer during aging in wooden barrels is a source of suitable craft ale yeast candidates. In contrast to the traditional lambic beer maturation phase, during the aging of sour-matured production-style beer, different biotypes of Saccharomyces cerevisiae dominated the cultivable in-house mycobiota, which were followed by Pichia membranifaciens, Brettanomyces bruxellensis, and Brettanomyces anomalus. In addition, three putative S. cerevisiae × Saccharomyces uvarum hybrids were identified. S. cerevisiae feral strains sporulated, produced viable monosporic progenies, and had the STA1 gene downstream as a full-length promoter. During hopped wort fermentation, four S. cerevisiae strains and the S. cerevisiae × S. uvarum hybrid WY213 exceeded non-Saccharomyces strains in fermentative rate and ethanol production except for P. membranifaciens WY122. This strain consumed maltose after a long lag phase, in contrast to the phenotypic profile described for the species. According to the STA1+ genotype, S. cerevisiae partially consumed dextrin. Among the volatile organic compounds (VOCs) produced by S. cerevisiae and the S. cerevisiae × S. uvarum hybrid, phenylethyl alcohol, which has a fruit-like aroma, was the most prevalent. In conclusion, the strains characterized here have relevant brewing properties and are exploitable as indigenous craft beer starters. Full article

Non-Saccharomyces yeasts represent a great source of biodiversity for the production of new beer styles, since they can be used in different industrial areas, as pure culture starters, in co-fermentation with Saccharomyces, and in spontaneous fermentation (lambic and gueuze production, with the main contribution of Brettanomyces yeast). The fermentation process of lambic beer is characterized by different phases with a characteristic predominance of different microorganisms in each of them. As it is a spontaneous process, fermentation usually lasts from 10 months to 3 years. In this work, an attempt was made to perform a fermentation similar to the one that occurred in this process with lactic bacteria, Saccharomyces yeast and Brettanomyces yeast, but controlling their inoculation and therefore decreasing the time necessary for their action. For this purpose, after the first screening in 100 mL where eight Brettanomyces yeast strains from D.O. “Ribeira Sacra” (Galicia) were tested, one Brettanomyces bruxellensis strain was finally selected (B6) for fermentation in 1 L together with commercial strains of Saccharomyces cerevisiae S-04 yeast and Lactobacillus brevis lactic acid bacteria in different sequences. The combinations that showed the best fermentative capacity were tested in 14 L. Volatile compounds, lactic acid, acetic acid, colour, bitterness, residual sugars, ethanol, melatonin and antioxidant capacity were analysed at different maturation times of 1, 2, 6 and 12 months. Beers inoculated with Brettanomyces yeast independently of the other microorganisms showed pronounced aromas characteristic of the Brettanomyces yeast. Maturation after 12 months showed balanced beers with “Brett” aromas, as well as an increase in the antioxidant capacity of the beers. Full article

Sour beers have been traditionally brewed with spontaneous fermentation. This has been occurring in Belgium for hundreds of years, and more recently in the United States as the American craft beer industry has boomed. Belgian sour styles include lambics, which are mirrored in a burgeoning style called the American coolship ale (ACA). American beers have much more creative leeway than their Belgian counterparts, as American craft brewing tends to incorporate more contemporary techniques and ingredients than their traditional European forebears. This review paper will summarize the history, production methods, fermentation, microbiological profiles, and sensory profiles of Belgian lambics and American coolship ales. Full article

Lambic beer is produced using spontaneous fermentation. Gueuze is a style of lambic beer that blends “young” (1 year old) and “aged” (2+ years old) beers. Little is known about the development of volatile aroma compounds in lambic beer during aging. Solid-phase microextraction and gas chromatography–mass spectrometry were used to analyze volatile compounds from 3, 6, 9, 12, and 28-month-old commercial samples of lambic beer. Compounds were identified using standardized retention time and mass spectra of standards. Gas chromatography–olfactometry was used to characterize the aroma profiles of the samples. A total of 41 compounds were identified using gas chromatography–mass spectrometry (GC–MS). Ethyl lactate, ethyl acetate, 4-ethylphenol and 4-ethylguaiacol were identified in the 9, 12, and 28-month old samples. These four compounds have been linked to the microorganism Brettanomyces. Twenty-one aroma active compounds were identified using Gas chromatography–olfactometry (GC–O). As the age of the gueuze samples increased, a larger number of aroma compounds were identified by the panelists; the compounds identified increased from seven for the 3-month-old samples to nine for the 6-month-old samples, and eleven for both the nine and twelve-month-old samples, and seventeen for the twenty-eight-month-old samples. Full article

Lambic beer is the oldest style of beer still being produced in the Western world using spontaneous fermentation. Gueuze is a style of lambic beer prepared by mixing young (one year) and older (two to three years) beers. Little is known about the volatiles and semi-volatiles found in commercial samples of gueuze lambic beers. SPME was used to extract the volatiles from nine different brands of lambic beer. GC-MS was used for the separation and identification of the compounds extracted with SPME. The pH and color were measured using standard procedures. A total of 50 compounds were identified in the nine brands. Seventeen of the 50 compounds identified have been previously identified. The compounds identified included a number of different chemical groups such as acids, alcohols, phenols, ketones, aldehydes, and esters. Ethyl acetate, 4-ethylphenol, and 4-ethylguaiacol are known by-products of the yeast, Brettanomyces, which is normally a spoilage microorganism in beer and wine, but important for the flavor characteristics of lambic beer. There were no differences in pH, but there were differences in color between the beer samples. Full article