Yeast and fermentation

Biochemistry resulted from the early elucidation of the pathway of enzymatic conversion of glucose to ethanol by yeasts and its relation to carbohydrate metaboHsm in animals. The word enzyme means "in yeast," and the earfler word ferment has an obvious connection. Partly because of the importance of wine and related products and partly because yeasts are relatively easily studied, yeasts and fermentation were important in early scientific development and stiU figure widely in studies of biochemical mechanisms, genetic control, cell characteristics, etc. Fermentation yeast was the first eukaryote to have its genome elucidated. 

Girond, S., Blazy-Maugen, F., Michel, G., and Bosch, M. (1989). The influence of some pesticides on yeasts and fermentation. Rev. Fr. d Oemologie Paris 29,14—22. 

Bisson, L. F. (1991). Influence of nitrogen on yeast and fermentation of grapes. In proceedings of the international symposium on nitrogen in grapes and wine. Am. Soc. Enol. Vitic. 323, 78-89. 

Delaquis, R, Cliff, M., King, M., Girare, B., Hall, J., Reynolds, A. (2000). Effect of two commercial malolactic cultures on the chemical and sensory properties of Chancellor wines vinified with different yeasts and fermentation temperatures. Am. J. EnoL Vitic., 51, 42 8. 

Fermentation temperature and fermentor design can induce evaporative alcohol losses but these are relatively small. Based on current state of knowledge, choice of yeast and fermentation conditions constrain wine style and do not provide a reliable approach for achieving at least a one percent or greater loss of potential alcohol content of wine (Boulton et al. 1998 de Barros Lopes et al. 2003 Palacios et al. 2007). Several physical techniques, such as spinning-cone and reverse osmosis, and nanofiltration can be used to remove sufficient sugar or alcohol for the production of reduced or low alcohol products (Ferrarini et al. 2008 Grosser 2008). 

There has been a growing application of metabolomics to wine yeast and fermentation as more people have recognized the power of these techniques. One application of metabolomics has been to study the interactions of yeast during fermentation. Howell et al. (2006) used metabolic profiling to study how multiple strains of Saccharomyces spp. grown together in grape juice affect the flavor and aroma compotmds in the fermented wine. 

Add malt extracts to 2 gallons of water and bring to a boil. Add 1 ounce of Hallertauer hops and boil for 55 minutes. Add 1 ounce of Hallertauer hops and boil for 5 more minutes. Turn off heat and add 3 gallons of very cold water to wort and transfer to primary fermenter. Pitch yeast and ferment for 25 days. Prime with V2 cup com sugar and bottle. 

Toast 1 pound of pilsner malt in oven at 250 for 1 hour. Mash grains in with 12 quarts water. Raise temperature to 140° and hold for 30 minutes. Raise temperature to 154° and hold for 60 minutes. Raise temperature to 168° and hold for 30 minutes. Sparge and collect 6 /z gallons of wort. Bring to a boil and add IV2 ounces of Hallertauer hops. Boil for 20 minutes and add 1 ounce of Hallertauer hops. Boil for 20 minutes and add % ounce of Saaz hops. Boil for afinal 20 minutes and turn offbeat. Force-cool with a wort chiller and transfer to a primary fermenter. Pitch yeast and ferment for 4 weeks at 42°. Rack to a secondaryfermenterandfermentforanother3monthsat42°. Prime with Vzcup com sugar and bottle. 

Bring wort to a boil and boil for 10 minutes. Add Vs ounce of Chinook hops and boil for 30 minutes. Add Vi ounce of Perle hops and boil for 15 minutes. Add Irish moss and hoil a final 15 minutes. Turn offbeat and add Vz ounce each of Hallertauer and Tettnanger hops and let steep. Force-cool with a chiller, then transfer to a primary fermenter. Rtch yeast and ferment for 11 days at 45°. Rack to a secondary fermenter and ferment for 45 days at 45°. Prime with % cup com sugar and bottle. Lager for 35-40 days at 32°. 

Bring malt extract and 2 gallons of water to a boil. Boil for 2 minutes and add hops. Boil for 58 minutes and turn offbeat. Add tea bags, set kettle in bathtub filled with cold water, and let sit for 1 hour. Transfer to a primary fermenter and bring up to 2 Vz gallons with pre-boiled water. Pitch yeast and ferment for 7 days at 60°. Prime with Vi cup com symp and bottle. 

Cleanliness is especially necessary in the case of the yeast and fermenting tubs, where the intrusion of these organisms will cause serious trouble. The walls of the distillery should be kept free from mold by an occasional coat of whitewash. The floors should be flooded daily, and the sewer connections must be adequate to remove the water and other wastes from the premises. 

Boulton, C., Quain, D. (2001). Brewing yeast and fermentation. India Blackwell Publishing Ltd. 

In-process or in-line measurements throughout the entire brewing process, and for yeast and fermentation parameters in particular, are growing in significance and have... 

Pilsner beer A type of beer produced with top-fermenting yeast and fermented at a relatively high temperature. 

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