Fermentation bottom

Bottom fermentation involves a primary and a secondary step. In the primary fermentation step, the cooled wort with about 6.5-18% dry mass extracted from malt ( stemwort ) is pumped into fermenting tanks, located in fermentation cellars cooled to 5-6 °C. The tanks are made of plastic-lined concrete, enamelcoated steel, aluminum or V2A steel. The wort is inoculated ( pitched ) with yeast in the form of a thick yeast slurry of Saccharomyces Carls-bergensis (0.5-11/hl) and fermented at 8-14 °C until more than 90% of the fermentable extract has been converted. The primary fermentation is completed in 7-8 days, at which point the yeast breaks , i. e., flocculates and settles to the bottom. The beer is transferred to large clean 

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Bottle seals Bottling Bottom-fermented beers... 

Since the 1960s the overall number of types has been decreasing, or at least remained unchanged (standard products), but some figures indicate that in the future the creation of new products might take place as a strong alternative to the previous mass-produced beers of less body or character. A traditional and overall grouping of beer can nevertheless stiU be made, ie, bottom-fermented beet and top-fermented beer. 

Fermentation is carded out in two different, very distinct ways top fermentation and bottom fermentation. The governing principles are the same in both processes the chief differences are in the type of yeast and temperature employed, and consequently the method used for collecting the yeast after fermentation is finished. The alcohol content and, to a higher degree, the taste and stabiUty of the beer, are directly dependent on the normal progress of the fermentation. 

Unter gdrung, /. bottom fermentation, -gat-tung, /. subgenus. 

Bottom-fermenting yeasts, 26 465 Bottom-pressure casting method, 23 269 Bottom-spray fluidized-bed units, 16 448-449... 

Yoshimoto, H., Eujiwara, D., Momma, T., Ito, C, Sone, H., Kaneko, Y., Tamai, Y. (1998) Characterization of the ATEl and Lg-ATFl genes encoding alcohol acetyltransferases in the bottom fermenting yeast Saccharomyces pastorianus. Journal of Fermentation and Bioengineering, 86, 15-20. 

In 1903 Claussen obtained a patent in England for his process of adding Brettanomyces yeast "to impart the characteristic flavour and condition of English beers to bottom-fermentation beers and for improving English beers" (3). At that time it was unknown how the wine-like flavor developed in British beers. Brewers used the method developed by Hansen in 1883 for the inoculation of pure yeasts in bottom fermented beers however, they were unsuccessful in their attempts to use the method to recreate the flavors of well-conditioned top fermented English stock beers. These were stored in cask, vat or bottle for more than a week after racking. 

The bottom fermentation is divided into main and secondary fermentation. For the main fermentation, the cooled-down flavouring, which contains approx. 6.5-18% malt extract, is combined in fermentation containers with yeast (approx. 1 litre per hectolitre) and fermented at a temperature of 6-10°C for 6-10 days within this period approx. 90% of the fermentable extract is transformed. 

Table 5.18 Different types of beer According to the used yeasts the beers are classified in top-fermenting and bottom-fermenting beers...

Lagers comprise more than 95% of the brew sold in the U.S. A., but just over 40% of the beer sales in Canada, and less than 5% of the beer sold in the U.K. More than 50% of the beer sold in Canada and nearly 90% of that sold in the U.K. is an ale. The basic difference between these brews is that, an ale is produced by a top-fermenting yeast, such as Saccharomyces cerevisiae, from which the yeast is skimmed from the top of the beer on completion of fermentation. Fermentation with these yeasts is carried out at 15-20°C, slightly higher than bottom fermentations. Ales are also hopped at a higher rate than lagers, which gives the product its characteristic more bitter, hoppy flavor. 

Port wine is fermented in shallow receptacles of masonry in which the grapes are trodden and, after fermentation, pressed. Fermentation in Italy, Spain, and the south of France is carried out at 15° to 24° C., and is a top fermentation, but in Germany and with the finer French wines, a bottom fermentation is made at 5° to 12° C. At the higher temperature the fermentation takes from 3 to 8 days, and the wine produced is fiery, high in alcohol, and lacking in delicate aroma. At the lower temperature the first fermentation lasts a few weeks, but yields a wine of delicate flavour. When fermentation is complete, and the wine has become clear, all the yeast aud other suspended matters are deposited oil the bottom of the cask or vat, constituting the lees. From this the young wine is racked, i.e. decanted or siphoned off, and run into a clean cask. 

Saccharomyces cerevisiae. The ordinary yeast of the brewer and the distiller. Two kinds are recognized (a) top fermentation, and (b) bottom fermentation. 

Cloning of the ATFl and Lg-ATFl Genes from the Bottom Fermenting Yeast... 

The different results which we have just set forth, and hich are due to H. Brown, relate only to yeast of top fermenta-Dn. Petit, by an analogous method, has determined in a wort. e quantities of assimilable protein and assimilated pre)tein. hich disappeared in the main fermentation) per 100 parts of tract in the course of a bottom fermentation. Some of the jures found are ... 

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