Transcript Beer
Beer MGMT 252 – Wine Industry Fenix Theuerkorn – VIU Introduction • As we have learned yeast is responsible for the fermentation of wine from the conversion of sugar into alcohol • Bread, beer, and wine are the main food products associated with yeast fermentations • Saccharyomyces cerevisiae is the most common yeast species for these purposes Bread • Ancient societies used grains to produce porridges, gruels, and unleavened bread • As societies became more sophisticated, leavened breads became more popular • In early times, bakeries were often attached to breweries so that the yeast by-product of brewing (S. cerevisiae) could be used for bread-making • S. cerevisiae is commonly called “baker’s yeast” Beer Essential Ingredients • • • • hops for flavor and antimicrobial activity yeast to produce alcohol and CO2 water malted barley to provide fermentable carbohydrate hops Beer • German purity laws forbid the use of any other ingredients (1516) • Different hops give different beers their distinctive flavors • Other countries (including U.S.) allow less expensive cereals, grains, or corn to be used to replace malt as the carbohydrate Beer-making • Process consists of malting, mashing, wort boiling, fermentation, and postfermentation treatments • Yeast cannot ferment starch in the barley, so it is malted and mashed • Sweetness in beer comes from the malted barley Malting • Grain is steeped in water for 24 – 48 hrs to induce germination • This breaks down the cell wall and protein matrix that contains the starch granules and liberates amylases Mashing and Wort Boiling • Amylases break the starch into fermentable carbohydrates • After mashing, the liquid malt is almost ready to ferment • Herbs, usually hops, are added for flavor and antimicrobial activity • The mixture of hops and liquid malt is boiled and then cooled to ~20oC Fermentation ALES • S. cerevisiae grows on top of the fermentation mix and is used for ales LAGERS • S. carlsbergensis settles to the bottom and is used for lagers • Cooler fermentation Fermentation Fermentation • The yeast from one fermentation is used to inoculate the next batch for 10 – 15 fermentations and then, a new inoculum is reintroduced • The yeast uses the various sugars in the wort sequentially, with simple sugars being fermented first and maltotriose relatively later (except for some ales) Fermentation • Ethanol production continues after the yeast stops growing • Flavor compounds, such as aldehydes and higher alcohols, are produced Post-fermentation • Includes “aging” to remove the “green” flavors caused by diacetyl and acetaldehyde • These can impact the taste adversely as humans can taste them at very low concentrations • Aging in casks, storage in the presence of yeast at 15oC, and avoiding O2 exposure helps to remove flavor defects Post-fermentation • Most beers are filtered until clear, although cloudiness of “boutique” beers is part of their charm • Cellulose fiber or pumice are used as filter aids to enhance removal of the yeast by filtration Process: Brewing Beer Beer Character Color Color is from the type of grains and roasting level. Colors range from straw to black and most of the earth tones. Bitterness Bitterness is from the addition of hops during the boiling process. Bitterness levels are controlled by the amount and varieties of hops. Gravity The term “gravity” refers to the density of beer which is determined by the amount of soluble sugars in the beer. In North American this is usually measured as brix. The primary soluble sugar in beer is derived from the malted grain, which is called maltose. Major Beer Styles Ale • • • • Ales Lambic Stout Wheat Beer Lagers • • • • Lagers Pilsner Bock Märzen Exceptions: Beer using both ale & lager fermentation Steam beer Altbier Kölsch Influence of beer Karl Marx claimed communist revolution could not happen in Köln (Cologne)… … workers drink with their bosses.