Lager Fermentation Research Articles

A Preliminary Study on the Effect of Adding Sugarcane Syrup on the Flavor of Barley Lager Fermentation.

This study focuses on the diversified utilization of the sugarcane industry, and sugarcane syrup, as a by-product of the sugarcane industry, is a good raw material for fermentation. Bringing sugarcane syrup into beer is conducive to the enrichment of the sugar industry, and it can improve the flavor of beer and make it more aromatic. This study determined the optimal fermentation process for beer. By analyzing the consumption rate of the carbon and nitrogen sources of raw materials, the nutrient utilization of yeast, and the causes of differences in flavor substances, the flavor composition and flavor stability of beer were determined by SPME-HS-GC-MS technology. The results showed that beer brewed with sugarcane syrup as an auxiliary raw material met the basic specifications of beer. The addition of sugarcane syrup to the wort base increased the utilization of amino acids by the yeast, and LS (lager with added cane syrup) increased the nine flavor compounds of the beer, which constituted the basic flavor of the beer, bringing new flavor compounds compared with the normal all-barley beer. Forced aging experiments showed that LS produced fewer aging compounds than OWBL. Various experiments have shown that it is feasible to ferment beer with sugarcane syrup instead of partial wort.

Characterization of Cold-Tolerant Saccharomyces cerevisiae Cheongdo Using Phenotype Microarray.

The cold-tolerant yeast Saccharomyces cerevisiae is industrially useful for lager fermentation, high-quality wine, and frozen dough production. S. cerevisiae Cheongdo is a recent isolate from frozen peach samples which has a good fermentation performance at low temperatures and desirable flavor profiles. Here, phenotype microarray was used to investigate industrial potentials of S. cerevisiae Cheongdo using 192 carbon sources. Compared to commercial wine yeast S. cerevisiae EC1118, Cheongdo showed significantly different growth rates on 34 substrates. The principal component analysis of the results highlighted that the better growth of Cheongdo on galactose than on EC1118 was the most significant difference between the two strains. The intact GAL4 gene and the galactose fermentation performance at a low temperatures suggested that S. cerevisiae Cheongdo is a promising host for industrial fermentation rich in galactose, such as lactose and agarose.

Hybridization of Saccharomyces cerevisiae Sourdough Strains with Cryotolerant Saccharomyces bayanus NBRC1948 as a Strategy to Increase Diversity of Strains Available for Lager Beer Fermentation.

The search for novel brewing strains from non-brewing environments represents an emerging trend to increase genetic and phenotypic diversities in brewing yeast culture collections. Another valuable tool is hybridization, where beneficial traits of individual strains are combined in a single organism. This has been used successfully to create de novo hybrids from parental brewing strains by mimicking natural Saccharomyces cerevisiae ale × Saccharomyces eubayanus lager yeast hybrids. Here, we integrated both these approaches to create synthetic hybrids for lager fermentation using parental strains from niches other than beer. Using a phenotype-centered strategy, S. cerevisiae sourdough strains and the S. eubayanus × Saccharomyces uvarum strain NBRC1948 (also referred to as Saccharomyces bayanus) were chosen for their brewing aptitudes. We demonstrated that, in contrast to S. cerevisiae × S. uvarum crosses, hybridization yield was positively affected by time of exposure to starvation, but not by staggered mating. In laboratory-scale fermentation trials at 20 °C, one triple S. cerevisiae × S. eubayanus × S. uvarum hybrid showed a heterotic phenotype compared with the parents. In 2 L wort fermentation trials at 12 °C, this hybrid inherited the ability to consume efficiently maltotriose from NBRC1948 and, like the sourdough S. cerevisiae parent, produced appreciable levels of the positive aroma compounds 3-methylbutyl acetate (banana/pear), ethyl acetate (general fruit aroma) and ethyl hexanoate (green apple, aniseed, and cherry aroma). Based on these evidences, the phenotype-centered approach appears promising for designing de novo lager beer hybrids and may help to diversify aroma profiles in lager beer.

Fate of the mycotoxins in the wort and yeast during ale and lager fermentation and their evaluation under different technological parameters

This study aimed to evaluate the mycotoxins transfer in the wort and yeast during ale and lager fermentation, secondary fermentation, and beer storage. Four yeasts were used to ferment wort contaminated with DON and ZEN. The wort was fermented with two S. cerevisiae yeasts (yeasts A and B) at 15, 20, 25 °C for 96 h, and two S. pastorianus (yeasts C and D) at 10, 15, 20 °C for 144 h. After fermentation, the two wort with the highest mycotoxin decrease were selected for a second fermentation and stored period. Mycotoxins were extracted using QuEChERS and analyzed by UHPLC-DAD/FLD. In the wort, DON decreased from 11% to 27%, locating it adsorbed on the yeast from LOD to 6.16%. ZEN in the wort decreased from 29% to 90%, locating it adsorbed on the yeast from 5.41% to 33.86%. Ale-fermentation process obtained the highest decrease of ZEN in the wort, whereas, for DON, there was no significant difference in the reduction between the 2 fermentation styles. Finally, there was no significant change in mycotoxin content during storage. Knowledge of the mitigating effect of fermentation variables could help to reduce the mycotoxin content in beer.

Rapid Beer Fermentation: The Effect of Vacuum Pressure on a Pilot Scale Lager Fermentation

Changes to industrial fermentation processes are rare, largely due to the impact on viability for Saccharomyces spp., related to environmental stresses during the process such as: osmotic pressure, ethanol concentration, dissolved CO2. This research studied yeast behavior during a High Gravity (HG) fermentation under partial vacuum pressure during standard brewing operations. This was accomplished by controlling the temperature and pressure of 30 L pilot fermentations. An experimental lager wort recipe with “Diamond” lager yeast (Saccharomyces pastorianus) was used in this study. The modified process conducted at 24.1 kPa of pressure in the headspace was compared to a control process at standard atmospheric pressure (101.3 kPa). This research showed that at 15 °C, lager fermentations (14–15°P) fermented up to 30% faster under vacuum, with an increase in the number of yeast cells in suspension of up to 100%. The rate of sugar consumption under vacuum was greater compared to the control, thus increasing the rate of ethanol production. The removal of volatile CO2 is one hypothesized mechanism for these results. The total ethanol production, pH and yeast viability did not differ significantly between the control and modified process. The application of vacuum during brewing resulted in an increased fermentation rate and number of yeast cells in suspension during fermentation.

Intracellular metabolite profiling of industrial yeast and the synthesis of flavour compounds in beer

Beer quality is largely guaranteed by a rational ratio of different flavour compounds. In this study, we present intracellular metabolic profiles in the light of lager beer flavour compound synthesis on an industrial scale. A total of 62 intracellular metabolites were identified and quantitatively analysed. Among these, amino acid was identified as the most dominant category of metabolites. We also report gene expression profiling of relevant genes encoding six representing amino acids, including serine, alanine, lysine, valine, leucine and asparagine. Nine genes involved in the amino acid synthesis – ALT1, ALT2, ASN1, ASN2, BAT1, SER2, SHM1, SHM2 and LYA1 – displayed significantly higher level of expression at various fermentation stages in an industrial lager fermentation. However, concentrations of the recovered amino acids decreased towards the end of fermentation. Our results suggested that the defined amino acids could be assimilated by the yeast to be utilized for synthesis of aroma-active metabolites at different stages in fermentation. Copyright © 2017 The Institute of Brewing & Distilling

Image-Based Cytometric Analysis of Fluorescent Viability and Vitality Staining Methods for Ale and Lager Fermentation Yeast

Saccharomyces cerevisiae have been an essential component of beer production for centuries. The viability and vitality of yeast during a fermentation brewing process is an especially important consideration for proper cell growth, consistent flavor, and optimal production yield. The current definition of viability refers to yeast with intact membranes, while vitality refers to yeast with quantifiable metabolic activity and an ability to proliferate. Yeast may be viable, but may not be actively proliferating, which can affect the fermentation process. The traditional method for measuring yeast viability utilizes manual counting of methylene blue stained yeast cells in a hemacytometer. However, this method can be time consuming and has user-dependent variations. In this work, we demonstrate the capability of Cellometer Vision image cytometry for multi-fluorescent yeast viability and vitality measurements. Nine fluorescent stains were tested with this image cytometry system, including nucleic acid stains (PI, EB, 7-AAD, and DAPI), membrane potential, intracellular, and enzymatic stains (oxonol, MgANS, and CFDA-AM), as well as dual-fluorescent stains (AO/PI and CFDA-AM/PI). Each combination was validated against the traditional methylene blue method. Most importantly, we performed a time-course study to compare the viability and vitality of lager and ale yeast at Avery Brewing Company, which was used to better understand the physical and metabolic characteristics of yeast throughout the fermentation process. The results provide baseline knowledge for monitoring yeast health that may improve quality assurance procedures and produce more consistent beverage products (quality, flavor, alcohol content, etc.).

Production of Lager Beers from Different Types of Sorghum Malts and Adjuncts Supplemented with β-Amylase or Amyloglucosidase

Sorghum has been used in lager beer production as a source of malt and brewing adjuncts and it is viewed as an excellent choice for the production of gluten-free beers. In this research, lager beers produced from white or red sorghum malts, waxy or regular sorghum adjuncts, and β-amylase or amyloglucosidase supplementation were evaluated and compared with a control beer produced from barley malt. Worts were produced by a double-mashing procedure and brewed by typical lager fermentation. The addition of β-amylase increased the amount of fermentable sugars in the sorghum malt worts. When amyloglucosidase was added, the total sugar content was augmented 20% and the glucose content was five times higher compared with worts without exogenous enzymes. Barley and sorghum malt worts contained adequate amounts of free amino nitrogen contents. After fermentation, the barley malt beers contained approximately 1% more ethanol compared with the sorghum malt counterparts that were not supplemented with exogenous amylolytic enzymes. In beers supplemented with amyloglucosidase, the ethanol augmented 1.1% units and contents were comparable independently of the sort of malt. Fusel alcohol concentrations did not differ among treatments. The higher yields of 100% gluten-free sorghum beers were achieved when worts were supplemented with amyloglucosidase during mashing.

Selenite biotransformation during brewing. Evaluation by HPLC–ICP-MS

Yeast (Saccharomyces cerevisiae) and lactic bacteria have shown their ability to accumulate and transform inorganic selenium into organo Se compounds. The objective of this work was to evaluate selenium biotransformation during brewing by using S. cerevisiae and Saccharomyces uvarum for Ale and Lager fermentation, respectively. Se-enriched beer was produced by the addition of sodium selenite (0, 0.2, 1.0, 2.0, 10.0, 20.0μgSemL−1, respectively) to the fermentation media composed of yeast, malt extract and water. The alcoholic fermentation process was not affected by the presence of selenium regardless of the type of Saccharomyces being used. The percentage of selenium incorporated into beer, added between 1.0 and 10μgmL−1 was 55–60% of the selenium initially present. Se-compounds in post-fermentation (beer and yeast) products were investigated by using an analytical methodology based on HPLC–ICP-MS. For this purpose, several sample treatments, including ultrasonic-assisted enzymatic hydrolysis, in conjunction with different separation mechanisms like dialysis and anion exchange HPLC chromatography were applied for unambiguously identifying Se-species that produce during brewing. Selenomethionine was the main selenium compound identified in beer and yeast, being this species in the only case of the former not associated to peptides or proteins.

Yeast genome-wide expression analysis identifies a strong ergosterol and oxidative stress response during the initial stages of an industrial lager fermentation.

Genome-wide expression analysis of an industrial strain of Saccharomyces cerevisiae during the initial stages of an industrial lager fermentation identified a strong response from genes involved in the biosynthesis of ergosterol and oxidative stress protection. The induction of the ERG genes was confirmed by Northern analysis and was found to be complemented by a rapid accumulation of ergosterol over the initial 6-h fermentation period. From a test of the metabolic activity of deletion mutants in the ergosterol biosynthesis pathway, it was found that ergosterol is an important factor in restoring the fermentative capacity of the cell after storage. Additionally, similar ERG10 and TRR1 gene expression patterns over the initial 24-h fermentation period highlighted a possible interaction between ergosterol biosynthesis and the oxidative stress response. Further analysis showed that erg mutants producing altered sterols were highly sensitive to oxidative stress-generating compounds. Here we show that genome-wide expression analysis can be used in the commercial environment and was successful in identifying environmental conditions that are important in industrial yeast fermentation.

Trends in Wort Carbohydrate Utilization

A gas chromatographic method suitable for any type of low-molecular-weight carbohydrate analysis has been utilized to determine the individual wort sugars in corn adjunct wort from a Western Canadian brewery. The fluctuations in each sugar during primary lager fermentation have been graphed. “End fermented” wort has been shown to contain some maltotriose, a small amount of maltose, and the nonfermentable carbohydrates, including maltotetraose, maltopentose, and dextrins.

TRYPTOPHOL, TYROSOL AND PHENYLETHANOL-THE AROMATIC HIGHER ALCOHOLS IN BEER

A gas chromatographic method is presented for routine quantitative analysis of aromatic higher alcohols in beer. A satisfactory overall order of reproducibility, sensitivity and simplicity was achieved under the conditions described. This method has been used to compare finished Canadian ales and lagers. It was possible to differentiate an ale from a lager fermentation by the tryptophol content of the product. Experiments were conducted to investigate the influence of several factors on the concentration levels of aromatic higher alcohols. These compounds are produced by the yeast during fermentation and the levels achieved depend upon the type of yeast used, the fermentation conditions, and differences in the wort fermented.

Trends in Wort Carbohydrate Utilization

A gas chromatographic method suitable for any type of low-molecular-weight carbohydrate analysis has been utilized to determine the individual wort sugars in corn adjunct wort from a Western Canadian brewery. The fluctuations in each sugar during primary lager fermentation have been graphed. "End fermented" wort has been shown to contain some maltotriose, a small amount of maltose, and the nonfermentable carbohydrates, including maltotetraose, maltopentose, and dextrins.