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1.
Saerens SM Verbelen PJ Vanbeneden N Thevelein JM Delvaux FR 《Applied microbiology and biotechnology》2008,80(6):1039-1051
During fermentation, the yeast Saccharomyces cerevisiae produces a broad range of aroma-active substances, which are vital for the complex flavour of beer. In order to obtain insight
into the influence of high-gravity brewing and fermentation temperature on flavour formation, we analysed flavour production
and the expression level of ten genes (ADH1, BAP2, BAT1, BAT2, ILV5, ATF1, ATF2, IAH1, EHT1 and EEB1) during fermentation of a lager and an ale yeast. Higher initial wort gravity increased acetate ester production, while the
influence of higher fermentation temperature on aroma compound production was rather limited. In addition, there is a good
correlation between flavour production and the expression level of specific genes involved in the biosynthesis of aroma compounds.
We conclude that yeasts with desired amounts of esters and higher alcohols, in accordance with specific consumer preferences,
may be identified based on the expression level of flavour biosynthesis genes. Moreover, these results demonstrate that the
initial wort density can determine the final concentration of important volatile aroma compounds, thereby allowing beneficial
adaptation of the flavour of beer. 相似文献
2.
Maya P. Piddocke Stefan Kreisz Hans Peter Heldt-Hansen Kristian Fog Nielsen Lisbeth Olsson 《Applied microbiology and biotechnology》2009,84(3):453-464
High-gravity brewing, which can decrease production costs by increasing brewery yields, has become an attractive alternative
to traditional brewing methods. However, as higher sugar concentration is required, the yeast is exposed to various stresses
during fermentation. We evaluated the influence of high-gravity brewing on the fermentation performance of the brewer’s yeast
under model brewing conditions. The lager brewer’s strain Weihenstephan 34/70 strain was characterized at three different
gravities by adding either glucose or maltose syrups to the basic wort. We observed that increased gravity resulted in a lower
specific growth rate, a longer lag phase before initiation of ethanol production, incomplete sugar utilization, and an increase
in the concentrations of ethyl acetate and isoamyl acetate in the final beer. Increasing the gravity by adding maltose syrup
as opposed to glucose syrup resulted in more balanced fermentation performance in terms of higher cell numbers, respectively,
higher wort fermentability and a more favorable flavor profile of the final beer. Our study underlines the effects of the
various stress factors on brewer’s yeast metabolism and the influence of the type of sugar syrups on the fermentation performance
and the flavor profile of the final beer. 相似文献
3.
Blieck L Toye G Dumortier F Verstrepen KJ Delvaux FR Thevelein JM Van Dijck P 《Applied and environmental microbiology》2007,73(3):815-824
To save energy, space, and time, today's breweries make use of high-gravity brewing in which concentrated medium (wort) is fermented, resulting in a product with higher ethanol content. After fermentation, the product is diluted to obtain beer with the desired alcohol content. While economically desirable, the use of wort with an even higher sugar concentration is limited by the inability of brewer's yeast (Saccharomyces pastorianus) to efficiently ferment such concentrated medium. Here, we describe a successful strategy to obtain yeast variants with significantly improved fermentation capacity under high-gravity conditions. We isolated better-performing variants of the industrial lager strain CMBS33 by subjecting a pool of UV-induced variants to consecutive rounds of fermentation in very-high-gravity wort (>22 degrees Plato). Two variants (GT336 and GT344) showing faster fermentation rates and/or more-complete attenuation as well as improved viability under high ethanol conditions were identified. The variants displayed the same advantages in a pilot-scale stirred fermenter under high-gravity conditions at 11 degrees C. Microarray analysis identified several genes whose altered expression may be responsible for the superior performance of the variants. The role of some of these candidate genes was confirmed by genetic transformation. Our study shows that proper selection conditions allow the isolation of variants of commercial brewer's yeast with superior fermentation characteristics. Moreover, it is the first study to identify genes that affect fermentation performance under high-gravity conditions. The results are of interest to the beer and bioethanol industries, where the use of more-concentrated medium is economically advantageous. 相似文献
4.
Isolation and Characterization of Brewer's Yeast Variants with Improved Fermentation Performance under High-Gravity Conditions 总被引:2,自引:0,他引:2
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Lies Blieck Geert Toye Franoise Dumortier Kevin J. Verstrepen Freddy R. Delvaux Johan M. Thevelein Patrick Van Dijck 《Applied microbiology》2007,73(3):815-824
To save energy, space, and time, today's breweries make use of high-gravity brewing in which concentrated medium (wort) is fermented, resulting in a product with higher ethanol content. After fermentation, the product is diluted to obtain beer with the desired alcohol content. While economically desirable, the use of wort with an even higher sugar concentration is limited by the inability of brewer's yeast (Saccharomyces pastorianus) to efficiently ferment such concentrated medium. Here, we describe a successful strategy to obtain yeast variants with significantly improved fermentation capacity under high-gravity conditions. We isolated better-performing variants of the industrial lager strain CMBS33 by subjecting a pool of UV-induced variants to consecutive rounds of fermentation in very-high-gravity wort (>22° Plato). Two variants (GT336 and GT344) showing faster fermentation rates and/or more-complete attenuation as well as improved viability under high ethanol conditions were identified. The variants displayed the same advantages in a pilot-scale stirred fermenter under high-gravity conditions at 11°C. Microarray analysis identified several genes whose altered expression may be responsible for the superior performance of the variants. The role of some of these candidate genes was confirmed by genetic transformation. Our study shows that proper selection conditions allow the isolation of variants of commercial brewer's yeast with superior fermentation characteristics. Moreover, it is the first study to identify genes that affect fermentation performance under high-gravity conditions. The results are of interest to the beer and bioethanol industries, where the use of more-concentrated medium is economically advantageous. 相似文献
5.
K. Sigler D. Matoulková M. Dienstbier P. Gabriel 《Applied microbiology and biotechnology》2009,82(6):1027-1035
The net effect of increased wort osmolarity on fermentation time, bottom yeast vitality and sedimentation, beer flavor compounds,
and haze was determined in fermentations with 12° all-malt wort supplemented with sorbitol to reach osmolarity equal to 16°
and 20°. Three pitchings were performed in 12°/12°/12°, 16°/16°/12°, and 20°/20°/12° worts. Fermentations in 16° and 20° worts
decreased yeast vitality measured as acidification power (AP) by a maximum of 10%, lowered yeast proliferation, and increased
fermentation time. Repitching aggravated these effects. The 3rd “back to normal” pitching into 12° wort restored the yeast
AP and reproductive abilities while the extended fermentation time remained. Yeast sedimentation in 16° and 20° worts was
delayed but increased about two times at fermentation end relative to that in 12° wort. Third “back-to-normal” pitching abolished
the delay in sedimentation and reduced its extent, which became nearly equal in all variants. Beer brewed at increased osmolarity
was characterized by increased levels of diacetyl and pentanedione and lower levels of dimethylsulfide and acetaldehyde. Esters
and higher alcohols displayed small variations irrespective of wort osmolarity or repitching. Increased wort osmolarity had
no appreciable effect on the haze of green beer and accelerated beer clarification during maturation. In all variants, chill
haze increased with repitching. 相似文献
6.
Florian Kühbeck Michael Müller Werner Back Tomas Kurz Martin Krottenthaler 《Enzyme and microbial technology》2007,41(6-7):711-720
In this investigation, the effect of hot trub (a precipitation product of the wort boiling process in beer manufacturing) addition on fermentation performance was observed under variation of yeast vitality, and origin and the amount of hot trub. Its addition improved suspended cell concentrations for all yeast vitalities tested, and the more trub was added, the greater the effect. Further, pilot-scale fermentations showed significantly lower pH values and an accelerated extract degradation, thus, advancing fermentation by roughly 1 day for hot trub addition versus the fermentation of extremely bright wort. Since the positive effect of trub has often been associated with its particulate characteristics, fermentations with fractionated model particles, such as poly(vinylpyrrolidones) and kieselguhr, of different particle sizes were carried out under variation of yeast vitality and particle amounts. The addition of both particle types also improved fermentation performance, however, the effect was not as great as that of hot trub. Particulate material may improve the development of CO2 from the fermenting medium, thus reducing its concentration and inhibitory effect on yeast metabolism. The most effective fraction of kieselguhr had a 40 μm peak which also occurred in particle size distributions of all hot trubs investigated. This could be of particular interest when discussing particle effects. 相似文献
7.
S. G. Davydenko B. F. Yarovoy V. P. Stepanova D. V. Afonin B. E. Batashov A. T. Dedegkaev 《Russian Journal of Genetics》2010,46(11):1295-1305
Beer is a natural product and is a multicomponent system that has both positive and negative consumer properties. Organoleptical
off-flavors of beer are difficult to eliminate. Yeasts are the main active component of the system. The relationship between
beer quality and yeast usage is well known. New industrial strains for brewery are continuously developed. An industrial yeast
Saccharomyces cerevisiae strain was obtained and showed high technological properties, including efficient fermentation, a reduced production of sulfur
hydrate, and a high diacetyl reduction rate. The advantages made it possible to develop new brands of beer and nonalcoholic
products. The commercial use of the strain was patented. The strain was deposited in the Russian Collection of Industrial
Microorganisms. 相似文献
8.
Undesirable butter-tasting vicinal diketones are produced as by-products of valine and isoleucine biosynthesis during wort fermentation. One promising method of decreasing diacetyl production is through control of wort valine content since valine is involved in feedback inhibition of enzymes controlling the formation of diacetyl precursors. Here, the influence of valine supplementation, wort amino acid profile and free amino nitrogen content on diacetyl formation during wort fermentation with the lager yeast Saccharomyces pastorianus was investigated. Valine supplementation (100 to 300 mg L?1) resulted in decreased maximum diacetyl concentrations (up to 37 % lower) and diacetyl concentrations at the end of fermentation (up to 33 % lower) in all trials. Composition of the amino acid spectrum of the wort also had an impact on diacetyl and 2,3-pentanedione production during fermentation. No direct correlation between the wort amino acid concentrations and diacetyl production was found, but rather a negative correlation between the uptake rate of valine (and also other branched-chain amino acids) and diacetyl production. Fermentation performance and yeast growth were unaffected by supplementations. Amino acid addition had a minor effect on higher alcohol and ester composition, suggesting that high levels of supplementation could affect the flavour profile of the beer. Modifying amino acid profile of wort, especially with respect to valine and the other branched-chain amino acids, may be an effective way of decreasing the amount of diacetyl formed during fermentation. 相似文献
9.
Zhimin Yu Mouming Zhao Huiping Li Haifeng Zhao Qingli Zhang Chunyan Wan Huipin Li 《Biotechnology and Bioprocess Engineering》2012,17(4):818-826
High gravity (HG) or very high gravity (VHG) brewing has become popular in modern breweries due to its economic and product quality advantages. However, there are the negative impacts such as the fermentation performance of brewer??s yeast in HG or VHG wort, which are closely related to changes in cell physiological activity. In the present study, 3 kinds of worts, with different gravities, were used to examine the systematic effects on fermentation performance and physiological activity of lager yeast FBY009505 (Saccharomyces pastorianus) and ale yeast FBY0099 (Saccharomyces cerevisiae), as well as the resulting beer flavor. Results showed that the responses of FBY009505 and FBY0099 to the HG or VHG worts were similar. The specific fermentation rate and viability of cropped yeast of FBY009505 and FBY0099 were decreased with increasing wort gravity. The increased wort gravity resulted in the increase of energy charge and the decrease of ??-glucosides transport rate and glycolytic enzyme activities. Moreover, the environmental stresses in the HG or VHG wort showed a higher inhibitory activity against ??-glucoside transport than glycolytic enzymes. The content of intracellular trehalose and glycerol of FBY009505 and FBY0099 increased with the increase in wort gravity. The results from this study provided a potential means to systematically understand the physiology of brewer??s yeast under HG or VHG conditions. 相似文献
10.
Smogrovicova Daniela Domny Zoltan Gemeiner Peter Malovikova Anna Sturdik Ernest 《Biotechnology Techniques》1997,11(4):261-264
A continuous multistage column bioreactor with fluidised beds and continuous gas-lift bioreactor system with immobilised yeast Saccharomyces cerevisiae was developed for the first step of wort fermentation. The system of gas-lift reactor with yeast entrapped in calcium pectate beads was stable for 5 weeks by the optimal residence time of 12.75h and produced beer with a composition and flavour profile similar to that of beer produced by batch fermentation. Concentration of diacetyl was less than 0.1mg/l. 相似文献
11.
Inactivation of MXR1 Abolishes Formation of Dimethyl Sulfide from Dimethyl Sulfoxide in Saccharomyces cerevisiae
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Jrgen Hansen 《Applied microbiology》1999,65(9):3915-3919
Dimethyl sulfide (DMS) is a sulfur compound of importance for the organoleptic properties of beer, especially some lager beers. Synthesis of DMS during beer production occurs partly during wort production and partly during fermentation. Methionine sulfoxide reductases are the enzymes responsible for reduction of oxidized cellular methionines. These enzymes have been suggested to be able to reduce dimethyl sulfoxide (DMSO) as well, with DMS as the product. A gene for an enzymatic activity leading to methionine sulfoxide reduction in Saccharomyces yeast was recently identified. We confirmed that the Saccharomyces cerevisiae open reading frame YER042w appears to encode a methionine sulfoxide reductase, and propose the name MXR1 for the gene. We found that Mxr1p catalyzes reduction of DMSO to DMS and that an mxr1 disruption mutant cannot reduce DMSO to DMS. Mutant strains appear to have unchanged fitness under several laboratory conditions, and in this paper I hypothesize that disruption of MXR1 in brewing yeasts would neutralize the contribution of the yeast to the DMS content in beer. 相似文献
12.
The high degree of fermentability required in light beer production can be achieved by concurrent saccharification and fermentation of a wort containing an enzyme prepared corn syrup adjunct and glucoamylase. Traditional acid or acid-enzyme syrups used as adjuncts in regular beer production are not effective in a concurrent saccharification/fermentation process due to the presence of oligosaccharides that are resistant to the action of glucoamylase. 相似文献
13.
Yeast responses to stresses associated with industrial brewery handling 总被引:11,自引:0,他引:11
During brewery handling, production strains of yeast must respond to fluctuations in dissolved oxygen concentration, pH, osmolarity, ethanol concentration, nutrient supply and temperature. Fermentation performance of brewing yeast strains is dependent on their ability to adapt to these changes, particularly during batch brewery fermentation which involves the recycling (repitching) of a single yeast culture (slurry) over a number of fermentations (generations). Modern practices, such as the use of high-gravity worts and preparation of dried yeast for use as an inoculum, have increased the magnitude of the stresses to which the cell is subjected. The ability of yeast to respond effectively to these conditions is essential not only for beer production but also for maintaining the fermentation fitness of yeast for use in subsequent fermentations. During brewery handling, cells inhabit a complex environment and our understanding of stress responses under such conditions is limited. The advent of techniques capable of determining genomic and proteomic changes within the cell is likely vastly to improve our knowledge of yeast stress responses during industrial brewery handling. 相似文献
14.
P. J. Verbelen S. M. G. Saerens S. E. Van Mulders F. Delvaux F. R. Delvaux 《Applied microbiology and biotechnology》2009,82(6):1143-1156
The volumetric productivity of the beer fermentation process can be increased by using a higher pitching rate (i.e., higher
inoculum size). However, the decreased yeast net growth observed in these high cell density fermentations can have a negative
impact on the physiological stability throughout subsequent yeast generations. The use of different oxygen conditions (wort
aeration, wort oxygenation, yeast preoxygenation) was investigated to improve the growth yield during high cell density fermentations
and yeast metabolic and physiological parameters were assessed systematically. Together with a higher extent of growth (dependent
on the applied oxygen conditions), the fermentation power and the formation of unsaturated fatty acids were also affected.
Wort oxygenation had a significant decreasing effect on the formation of esters, which was caused by a decreased expression
of the alcohol acetyl transferase gene ATF1, compared with the other conditions. Lower glycogen and trehalose levels at the end of fermentation were observed in case
of the high cell density fermentations with oxygenated wort and the reference fermentation. The expression levels of BAP2 (encoding the branched chain amino acid permease), ERG1 (encoding squalene epoxidase), and the stress responsive gene HSP12 were predominantly influenced by the high cell concentrations, while OLE1 (encoding the fatty acid desaturase) and the oxidative stress responsive genes SOD1 and CTT1 were mainly affected by the oxygen availability per cell. These results demonstrate that optimisation of high cell density
fermentations could be achieved by improving the oxygen conditions, without drastically affecting the physiological condition
of the yeast and beer quality. 相似文献
15.
H. J. J. VAN VUUREN M. A. LOOS H. A. LOUW R. MEISEL 《Journal of applied microbiology》1979,47(3):421-424
Bacteria isolated from contaminated pitching yeast, fermenting wort and beer samples from a South African lager brewery over a one-year period were tentatively identified by an improved, rapid diagnostic procedure as pediococci (41%), homofermentative lactobacilli (5%), heterofermentative lactobacilli (9%), Acetobacter spp. (7%), Gluconobacter spp. (13%) and Hafnia protea (25%). Pediococci and lactobacilli dominated samples taken from fermentation, storage and 'bright' beer tanks but were absent from pitched wort samples, from collection vessels and the single pitching yeast sample investigated. Acetic acid bacteria and H. protea were widely distributed in collection vessel, fermentation and storage tank samples, and H. protea was isolated from recycled pitching yeast. 相似文献
16.
Influence of yeast immobilization on fermentation and aldehyde reduction during the production of alcohol-free beer 总被引:1,自引:0,他引:1
Production of alcohol-free beer by limited fermentation is optimally performed in a packed-bed reactor. This highly controllable system combines short contact times between yeast and wort with the reduction of off-flavors to concentrations below threshold values. In the present study, the influence of immobilization of yeast to DEAE-cellulose on sugar fermentation and aldehyde reduction was monitored. Immobilized cells showed higher activities of hexokinase and pyruvate decarboxylase compared to cells grown in batch culture. In addition, a higher glucose flux was observed, with enhanced excretion of main fermentation products, indicating a reduction in the flux of sugar used for biomass production. ADH activity was higher in immobilized cells compared to that in suspended cells. However, during prolonged production a decrease was observed in NAD-specific ADH activity, whereas NADP-specific activity increased in the immobilized cells. The shifts in enzyme activities and glucose flux correlate with a higher in vivo reduction capacity of the immobilized cells. 相似文献
17.
A fuzzy expert system was applied to the knowledge analysis of yeast physiology in the early stage of beer fermentation, when
the wort was aerated. We used ergosterol and glycogen concentration in the wort as a suitable marker of physiological state
of the cell population. The amount of both compounds influences the rate of fermentation, cell growth and the final taste
of beer. The concentrations of ergosterol and glycogen including the number of cells can not be measured immediately during
the relatively short aeration period, and incomplete experimental data are therefore found in laboratory logbooks. We therefore
suggested that the fuzzy relation between the directly measurable dissolved oxygen concentration and the rate of ergosterol
or glycogen formation should be identified and a fuzzy expert system should be used to analyze the behavior of the yeast. 相似文献
18.
This study focused on the interactions between yeast and zinc in relation to beer fermentations. Yeast accumulation of zinc from growth media, including malt wort, was found to be rapid following inoculation with a brewing strain of Saccharomyces carlsbergensis. In contrast, at the onset of the fermentation, the uptake of other divalent cations such as magnesium and calcium was not as pronounced compared with zinc. At the end of fermentation, both growth media and yeast cells became zinc-depleted, the latter due to dilution of zinc to daughter cells following growth and cell division. In addition, in brewing fermenters, the levels of intracellular zinc were much higher in suspended yeast cells compared with cells that sedimented in the yeast cone at the end of fermentation. This may result in impaired yeast performance in subsequent fermentations if yeast is recycled into low zinc media and if the sub-population is composed by zinc-depleted daughter cells. Cellular uptake of zinc was mediated by a metabolism-dependent mechanism as evidenced by impaired uptake following heat shock. Zinc was thereafter localised in the yeast cell vacuole. As industrial fermentation processes may occasionally be suppressed due to zinc deficiencies, the findings of this study are pertinent for several yeast-based industries, especially beer production. 相似文献
19.
Pieter J. Verbelen Tinne M. L. Dekoninck Sebastiaan E. Van Mulders Sofie M. G. Saerens Filip Delvaux Freddy R. Delvaux 《Biotechnology letters》2009,31(11):1729-1737
The volumetric productivity of the beer fermentation process can be increased by using a higher pitching rate (i.e. higher inoculum size). However, the decreased yeast net growth observed in these high cell density brewery fermentations can adversely affect the physiological stability throughout subsequent yeast generations. Therefore, different O2 conditions (wort aeration and yeast preoxygenation) were applied to high cell density fermentation and eight generations of fermentations were evaluated together with conventional fermentations. Freshly propagated high cell density populations adapted faster to the fermentative conditions than normal cell density populations. Preoxygenating the yeast was essential for the yeast physiological and beer flavor compound stability of high cell density fermentations during serial repitching. In contrast, the use of non-preoxygenated yeast resulted in inadequate growth which caused (1) insufficient yield of biomass to repitch all eight generations, (2) a 10% decrease in viability, (3) a moderate increase of yeast age, (4) and a dramatic increase of the unwanted flavor compounds acetaldehyde and total diacetyl during the sequence of fermentations. Therefore, to achieve sustainable high cell density fermentations throughout the economical valuable process of serial repitching, adequate yeast growth is essential. 相似文献
20.
Brányik T Silva DP Vicente AA Lehnert R e Silva JB Dostálek P Teixeira JA 《Journal of industrial microbiology & biotechnology》2006,33(12):1010-1018
Despite extensive research carried out in the last few decades, continuous beer fermentation has not yet managed to outperform the traditional batch technology. An industrial breakthrough in favour of continuous brewing using immobilized yeast could be expected only on achievement of the following process characteristics: simple design, low investment costs, flexible operation, effective process control and good product quality. The application of cheap carrier materials of by-product origin could significantly lower the investment costs of continuous fermentation systems. This work deals with a complete continuous beer fermentation system consisting of a main fermentation reactor (gas-lift) and a maturation reactor (packed-bed) containing yeast immobilized on spent grains and corncobs, respectively. The suitability of cheap carrier materials for long-term continuous brewing was proved. It was found that by fine tuning of process parameters (residence time, aeration) it was possible to adjust the flavour profile of the final product. Consumers considered the continuously fermented beer to be of a regular quality. Analytical and sensorial profiles of both continuously and batch fermented beers were compared. 相似文献