共查询到20条相似文献,搜索用时 31 毫秒
1.
J. A. Budd 《Applied microbiology and biotechnology》1977,3(4):267-272
Summary A culture of brewer's yeast,Saccharomyces cerevisiae (NCYC 240), maintained on Wickerham's MYGP medium, utilized the principal wort sugars sequentially in the order glucose-maltose-maltotriose, when inoculated into brewer's wort. A culture of the same strain maintained on brewer's wort utilized these three sugars simultaneously. Simultaneous utilization could be induced in MYGP-maintained cultures by successive sub-culture in brewer's wort, and appears to be the general rule of sugar uptake during wort fermentation under brewery conditions. 相似文献
2.
During the simultaneous-saccharification-fermentation from raw wheat starch, amyloglucosidase and commercial yeast, Saccharomyces cerevisiae, the fermentescible sugars profile, at the beginning of the process, plays a great role in the process regulation. From a liquefied wort, fermentescible sugars were glucose, maltose and maltotriose at concentration of 2 g/l, 40 g/l and 7 g/l, respectively. A complete hydrolysis of starch leads to a potential glucose concentration of 150 g/l. The general mechanism of a simultaneous-saccharification-fermentation occurs into two steps: the production of fermentescible sugars and the consumption of these by the yeast. In our case, maltose, dominating sugar in the wort, is the most significant sugar in the process regulation because it was substrate not only for the amyloglucosidase but also for the yeast. The maltose consumption by the yeast is repressed by the glucose, itself produced by the saccharification. We demonstrated that the apparent drop of maltose concentration in the wort acts as an activator of the amyloglucosidase and this fact allows a rapid ethanol production. The process is regulated by different interactions between glucose, maltose and maltotriose, the three sugars that, on one hand, are produced by the enzyme and on the other hand are used by the yeast. 相似文献
3.
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
4.
Joseph A. Odumeru Tony D'Amore Inge Russell Graham G. Stewart 《Journal of industrial microbiology & biotechnology》1992,10(2):111-116
Summary The effects of heat shock and ethanol stress on the viability of a lager brewing yeast strain during fermentation of high gravity wort were studied. These stress effects resulted in reduced cell viability and inhibition of cell growth during fermentation. Cells were observed to be less tolerant to heat shock during the fermentation of 25°P (degree Plato) wort than cells fermenting 16°P wort. Degree Plato (oP) is the weight of extract (sugar) equivalent to the weight of sucrose in a 100 g solution at 20°C. Relieving the stress effects of ethanol by washing the cells free of culture medium, improved their tolerance to heat shock. Cellular changes in yeast protein composition were observed after 24 h of fermentation at which time more than 2% (v/v) ethanol was present in the growth medium. The synthesis of these proteins was either induced by ethanol or was the result of the transition of cells from exponential phase to stationary phase of growth. No differences were observed in the protein composition of cells fermenting 16°P wort compared to those fermenting 25°P wort. Thus, the differences in the tolerance of these cells to heat shock may be due to the higher ethanol concentration produced in 25°P wort which enhanced their sensitivity to heat shock. 相似文献
5.
《Journal of Fermentation and Bioengineering》1992,73(5):370-374
The effect of sugar composition on the formation of acetate esters using immobilized yeast was investigated. When the immobilized yeast was incubated in maltose medium lacking unsaturated fatty acids, the production of ethyl acetate and isoamyl acetate was poor when compared to glucose medium, although in maltose medium the production of acetyl-CoA was less than in glucose medium. Ester production was stimulated using the immobilized yeast and wort treated with glucoamylase to hydrolyze maltose. With this method, acetate esters were produced at normal levels compared to those of beer fermented in the conventional manner. 相似文献
6.
Daniel Gold Ali Mohagheghi Charles L. Cooney Daniel I. C. Wang 《Biotechnology and bioengineering》1981,23(9):2105-2116
Spent sulfite liquor (SSL), a waste product of the paper pulping industry, is produced at a rate of 1 ton (dry basis) per ton of pulp. The sugar content of SSL is about 30 g/L. To reduce the biological oxygen demand (BOD) of SSL before disposal, torula yeast (Candida utilis) is produced by a continuous culture process, the productivity of which is limited by sugar concentration and cell growth rate. To increase productivity, a recycle system has been designed and tested. Cells were sedimented continuously with a flocculating agent (bentonite) before being recycled to the fermentor. A bentonite concentration of 0.02 g/g cell was required. A computer monitoring system based on material balancing techniques was developed to monitor and control the recycle system. With this computer system, productivity was raised to 6.1 g/L h, with cell concentration up to 65 g/L in the recycle stream and 24 g/L in the fermentor. This represents a productivity increase of 150% over continuous culture with no recycle. 相似文献
7.
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
8.
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
9.
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
下载免费PDF全文
![点击此处可从《Applied microbiology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
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
10.
The design and application of a settler to a continuous fermentation process with yeast recycle were studied. The compact lamella-type settler was chosen to avoid large volumes associated with conventional settling tanks. A rationale of the design method is covered. The sedimentation area was determined by classical batch settling rate tests and sedimentation capacity calculation. Limitations on the residence time of the microorganisms in the settler, rather than sludge thickening considerations, was the approach employed for volume calculation. Fermentation rate tests with yeast after different sedimentation periods were carried out to define a suitable residence time. Continuous cell recycle fermentation runs, performed with the old and new sedimentation devices, show that lamella settler improves biomass recycling efficiency, being the process able to operate at higher sugar concentrations and faster dilution rates. 相似文献
11.
12.
Maya?P?Piddocke Alessandro?Fazio Wanwipa?Vongsangnak Man?L?Wong Hans?P?Heldt-Hansen Chris?Workman Jens?Nielsen Lisbeth?Olsson
Background
Addition of sugar syrups to the basic wort is a popular technique to achieve higher gravity in beer fermentations, but it results in dilution of the free amino nitrogen (FAN) content in the medium. The multicomponent protease enzyme Flavourzyme has beneficial effect on the brewer's yeast fermentation performance during high gravity fermentations as it increases the initial FAN value and results in higher FAN uptake, higher specific growth rate, higher ethanol yield and improved flavour profile. 相似文献13.
Jaroslava Pátková Daniela Šmogrovičová Zoltán Dömény Petra Bafrncová 《Biotechnology letters》2000,22(14):1173-1177
Using calcium alginate-entrapped yeast, 24% (w/w) wort was successfully fermented within 8 days. This is half the time needed for fermentation by free yeast. The highest ethanol concentration obtained was 10.5% (v/v). When the original wort gravity was increased, the specific rate of ethanol production remained constant 0.16 g gh–1 and the viability did not fall bellow 95% of living cells. Protection of cell against osmotic stress by gel matrix was also confirmed by trehalose measurement. The maximum intracellular trehalose content in calcium alginate-entrapped yeast was 3 times lower compared to free yeast at 30% (w/w) wort fermentation. 相似文献
14.
The effect of ammonium ions on the activity of alcohol:NAD-, L-malate:NAD-, L-glutamate:NADP-oxidoreductases was studied in wine yeast during fermentation of wine wort containing 18% of sugar, and also after the biomass cultivated in the conditions of nitrogen deficiency had been transferred to media with various amounts of nitrogen and carbohydrates. Ammonium stimulated the activity of all these enzymes during fermentation and their activity in the biomass transferred to a medium with a low content of nutrient component; its effect was less pronounced on a complete medium. 相似文献
15.
Cell recycle and vacuum fermentation systems were developed for continuous ethanol production. Cell recycle was employed in both atmospheric pressure and vacuum fermentations to achieve high cell densities and rapid ethanol fermentation rates. Studies were conducted with Saccharomyces cerevisiae (ATCC No. 4126) at a fermentation temperature of 35°C. Employing a 10% glucose feed, a cell density of 50 g dry wt/liter was obtained in atmospheric-cell recycle fermentations which produced a fermentor ethanol productivity of 29.0 g/liter-hr. The vacuum fermentor eliminated ethanol inhibition by boiling away ethanol from the fermenting beer as it was formed. This permitted the rapid and complete fermentation of concentrated sugar solutions. At a total pressure of 50 mmHg and using a 33.4% glucose feed, ethanol productivities of 82 and 40 g/liter-hr were achieved with the vacuum system with and without cell recycle, respectively. Fermentor ethanol productivities were thus increased as much as twelvefold over conventional continuous fermentations. In order to maintain a viable yeast culture in the vacuum fermentor, a bleed of fermented broth had to be continuously withdrawn to remove nonvolatile compounds. It was also necessary to sparge the vacuum fermentor with pure oxygen to satisfy the trace oxygen requirement of the fermenting yeast. 相似文献
16.
17.
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
18.
Control and prediction of the course of brewery fermentations by gravimetric analysis 总被引:1,自引:1,他引:0
A simple, fast and cheap test suitable for predicting the course of brewery fermentations based on mass analysis is described
and its efficiency is evaluated. Compared to commonly used yeast vitality tests, this analysis takes into account wort composition
and other factors that influence fermentation performance. It can be used to predict the shape of the fermentation curve in
brewery fermentations and in research and development projects concerning yeast vitality, fermentation conditions and wort
composition. It can also be a useful tool for homebrewers to control their fermentations. 相似文献
19.
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
20.
Three yeast strains were isolated from a spontaneously fermented native millet (Pennisetum typhoideum) malt beer (Oyokpo). One of the yeast isolates found to have the most highly fermenting capacity was characterised and identified as a strain of Saccharomyces cerevisiae. The yeast was then utilised as the pitching yeast in a subsequent controlled fermentation of millet wort at 20°C for 120 hours. Bitter leaf (Vernonia amagdalina) extract was used as the bittering and flavouring agent. The Oyokpo beer sample produced under these conditions was found to possess both chemical and organoleptic qualities comparable to some extent, to the conventional barley malt beer. At the end of fermentation, the pH, specific gravity, alcohol content, reducing sugar content and protein content of the beer were 4.11, 1.0308, 2.81% (v/v), 4.00 (mg/ml) and 0.84 (mg/ml) respectively. 相似文献