Brewing fermentations more profitable

High gravity brewing has been presented as an alternative to make beer more profitable. The fermentation of high concentrated wort normally stops prematurely due the high stress conditions imposed by osmotic pressure and high ethanol content. In this wort, initial oxygen content and yeast preconditioning were applied and compared when used to accelerate very high gravity (VHG) fermentations. This work showed that using pure oxygen instead of air, the fermentation time can be reduced in about 24h without changes in the higher alcohols and esters production profile. When the yeast is preconditioned with a mixture of unsaturated fatty acids and salts before pitching the wort, the fermentation batch can be reduced from 7 to 5 days achieving lower residual extract. This difference in the residual extract results in a beer with 1 % more ethanol, which corresponds to an increase of 18% in the productivity.info:eu-repo/semantics/publishedVersio

Novas metodologias para a fermentação alcoólica do soro de queijo

Em Portugal, são diariamente lançados no meio ambiente cerca de 1 milhão de litros de soro de queijo – fracção líquida resultante do fabrico de queijo. O impacte ambiental ocasionado por tal volume de efluentes, com elevada carga orgânica, é enorme. Recorrendo à tecnologia de DNA recombinante, modificou-se uma estirpe floculante de Saccharomyces cerevisiae sendo-lhe conferida capacidade para fermentar lactose. Com esta estirpe foram realizados ensaios de fermentação em contínuo, utilizando como substrato soro de queijo desproteinizado, possibilitando operar a uma taxa de diluição máxima de 0,45 hˉ¹, correspondente a uma produtividade volumétrica em etanol de cerca de 10 gLˉ¹hˉ¹, cerca de 7 vezes superior aos processos actualmente existentes. O processo integrado de recuperação da proteína e fermentação alcoólica permite uma redução superior a 90 % de CQO do soro, o que, por si só, se traduz numa enorme diminuição do impacte ambiental negativo, e, por outro lado, abre a porta à produção de etanol com viabilidade económica.Instituto de Biotecnologia e Química Fina (IBQF); PROLAC; Agência de Inovação; Fundação para a Ciência e Tecnologia (FCT)

Construction of a flocculent saccharomyces cerevisiae fermenting lactose

A flocculent Saccharomyces cerevisiae strain with the ability to express both the LAC4 (coding for b-galactosidase) and LAC12 (coding for lactose permease) genes of Kluyveromyces marxianus was constructed. This recombinant strain is not only able to grow on lactose, but it can also ferment this substrate. To our knowledge this is the first time that a recombinant S. cervisiae has been found to ferment lactose in a way comparable to that of the existing lactose-fermenting yeast strains. Moreover, the flocculating capacity of the strain used in this work gives the process several advantages. On the one hand, it allows for operation in a continuous mode at high cell concentration, thus increasing the system's overall productivity; on the other hand, the biomass concentration in the effluent is reduced, thus decreasing product separation/purification costs.Instituto de Biotecnologia e Química Fina (IBQF).Fundação para a Ciência e a Tecnologia (FCT) - PRAXIS XXI/BD/11306/97

Enhancement of metabolic rates of yeast flocculent cells through the use of polymeric additives

The influence of several polymeric additives on specific glucose uptake rate of flocs of a S. cerevisiae strain - S. cerevisiae NRRL Y 265 was studied. A special continuous membrane microreactor was used to measure glucose uptake on the presence of calcium and of the tested additives - two cationic polymers - bis(polyoxyethylene- bis(amine)) 20,000 and BPA 1,000 and one anionic polymer -- Magna Floc LT25. An increase on glucose uptake rate was always observed when comparing with calcium bound flocs. For bis(polyoxyethylenebis( amine)) 20,000 the increase was only 19% but for BPA 1,000 a value of more than 50% was observed. For Magna Floc LT25 a two fold increase was measured. The determination of floc size and porosity in the presence of the additives indicated that, on the basis of these parameters, it was not possible to explain the observed glucose uptake rates. The floc porosites in additive bound flocs were similar and 10% larger than for calcium bound flocs and glucose uptake rate was larger for the largest flocs - Magna Floc LT25 bound flocs were the largest followed by BPA t,000, bis(polyoxyethylene-bis(amine)) 20,000 and calcium bound flocs. These values disagree with what should be expected in diffusion controlled processes. The calculation of intercellular floc distance indicated that polymeric additives act on the reduction of diffusional limitations by increasing the available flux area for glucose inside the flocs. By analysing different kinds of packings, it was also observed that the packing arrangement for yeast cells in flocs is close to the cubic packing. The simulation of this arrangement for the obtained floc sizes confirmed that the 10% increase in floc porosity is sufficient to explain the increase in the available flux area

Continuous ethanol production from cheese whey permeate

Praxis XXI - BD/11306/97

Aspergillus niger β-galactosidase production by yeast in a continuous high cell density reactor

The continuous production of extracellular heterologous beta-galactosidase by a recombinant flocculating Saccharomyces cerevisiae, expressing the lacA gene (coding for beta-galactosidase) of Aspergillus niger was investigated. A continuous operation was run in a 6.51 airlift bioreactor with a concentric draft tube using lactose as substrate. Data on the operation with semi-synthetic medium with 50 and 100 g/l initial lactose concentrations are presented. The best result for beta-galactosidase productivity-6.2 x 10(5) U/l h-was obtained for a system operating at 0.24 h(-1) dilution rate and for a lactose concentration in the feed of 50 g/l. This value represents a 11-fold increase in beta-galactosidase productivity when compared to batch culture. Together with extracellular beta-galactosidase production an ethanol productivity of 9 g/l h was obtained for the bioreactor fed with 50 g/l initial lactose concentration at 0.45 h(-1) dilution rate. In addition to beta-galactosidase and ethanol production, this system allowed for complete lactose metabolism. The feasibility and advantages of using continuous high-cell-density systems operating with flocculent yeast cells for extracellular protein production is clearly shown

An industrial brewer’s yeast strain in very high gravity wort fermentations

In the beer production, the fermentation of worts whose gravity is higher than 18 ºP has been presented as an efficient way to improve the capacity of brewery facility without changes in the brewhouse. In this work, a brewer yeast strain was submitted to high gravity fermentations to evaluate the influence and the limits of the environmental parameters on the fermentation performance and final product profile. The variables included in this study were the primary fermentation temperature, wort concentration (extract) and yeast pitching rate. Static fermentations were carried out anaerobically in 2 L tall tubes (EBC recommendation for small scale brewing fermentations) with 15, 18 and 22 ºP wort, at constant temperature of 12, 15 and 18 ºC. The yeast was grown aerobically at 27 ºC in 15 ºP wort (saturated with air) and collect by filtration to inoculate by mass at different pitching rates of 12, 18 and 22 million cells/ml. Fermentations were monitored daily measuring the ethanol, extract, pH, temperature, biomass in suspension and viability. At the end of the primary fermentation, the green beer was analysed concerning diacetil, esters and high alcohols by gas chromatography. Fermentation data were statistically treated in order to obtain an optimum approach for the studied parameters. For statistical proposes, the fermentation performance was measured by ethanol produced, apparent extract and the fermentation time. Although the temperature has a positive effect on the indicators of the fermentation performance, the wort concentration has not a positive effect for all indicators. When the wort has higher concentration at the beginning of the fermentation, as expected, the fermentation takes longer to be finished with more ethanol produced. Considering that the produced ethanol, the fermentation time and the residual extract have the same level of interest for the brewing process, the statistical analysis showed that the optimal point for the wort concentration, fermentation temperature and pitching rate is 20 ºP, 18 ºC and 20x106 cell/ml, respectively. The optimal conditions were repeated and the beer profile regarding the aroma profile was determined