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21 Cards in this Set
- Front
- Back
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What is bread leavening?
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Leavening is achieved primarily primarily through the release of gas to produce a porous and spongy product. Various forms of bakers yeast are employed.
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What type of bakers yeast is used?
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The most common form is Sacchromyces cervisiae. Other forms of microbes such as coliform bacteria, certain Clostridial species, lactic acid bacteria and wild yeasts can be used as well.
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What does yeast metabolism require?
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It requires a source of fermentable sugar such as maltose or glucose. Because the yeast is aerobic in bread dough, the chief products of maltose fermentation are CO2 and water rather than alcohol(main product in beer and wine).
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Sourdough bread gets its unique tang from Lactobacillus sanfrancisco. TRUE/FALSE
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TRUE.
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By fermenting carbohydrates in fruits or grains anaerobically, they produce ethyl alcohol, as shown by which equation?
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C6H12O6--2C2H5OH+2CO2
(yeast + sugar=Ethanol+CO2) |
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What is necessary for Brewers yeast to convert the CHO in grain into ethyl alcohol?
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The barley must first be sprouted and softened to make its complex nutrients available to yeasts. This is called malting. It release amylases that convert starch to dextrins and maltose, and proteases that digest proteins.
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What is done with malt grain?
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It is soaked in warm water and ground up to prepare a mash. Sugar and starch supplements are then introduced to the mash mixture which is heated to 70C.
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What happens in the next step?
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Starch is then hydrolyzed by amylase, and simple sugars are released. Solid particles are removed.
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What is Wort?
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After solid particlea re removed, Wort, the clear fluid that comes off is rich in dissolved carbohydrates. It is then boiled for 2.5 hours with hops(the dried scales of the female flower of Humulus lupulus) to extract the bitter acids and resins that give aroma and flavor to the finishd product.
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When does fermentation actually begin?
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When Wort is inoculated with a species of Sacchromyces that has been specially developed for beer making.
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What is the difference between top and bottom yeasts?
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Top yeasts like S. cervisiae function at the surface and are used to produce the higher alcohol content of ales. Bottom yeasts such as S. uvarum function deep in the fermentation vat and are used to make other beers.
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Fermentation is self limited, and it essentially ceases when a concentration of 3-6% ethyl alcohol is reached. TRUE/FALSE
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TRUE.
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What is must?
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Wine is considered any alcoholic beverage arising from the fermentation of grape juice. Must is in the initial process. It is the juice given off by crushed fruit that is used as a substrate for fermentation.
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What is required of must for proper fermentation?
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Must should contain 12% to 25% glucose or fructose. Grapes are harvested when their sugar content reaches 15-25% depending on the type of wine to be made.
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What is bloom?
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Grapes from the field carry a mixed biofilm on their surface called the bloom that can serve as a source of wild yeasts. many wineries inoculate the must with a special strain of S. cervisiae.
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When or why is sulfur dioxide employed?
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To discourage yeast and bacterial spoilage agents, winemakers sometimes treat grapes with sulfur dioxide or potassium metabisulfite.
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Is the temperature in the vat important?
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Yes. It must be carefully controlled to facilotate alcohol production. The lenght of fermentation varies from 3-5 days in red wines and from 7-14 days in white wines.
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The standard fermentation process can only achieve a maximum alcoholic content of 17%, because concentrations above this level inhibit the the meatabolism of the yeast. TRUE/FALSE
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TRUE. The fermentation product must be distilled to obtain higher concentrations such as those found in liquors.
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What occurs during distillation?
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During this process, heating the liquor separates the more volatile alcohol from the less volatile aqueous phase.
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How are liquors distilled?
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In addition to distillation, liquors can be subjected to special treatments such as aging to provide unique flavor or color.
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What is vodka made from?
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Vodka, a colorless liquor, is usually prepared from fermented potatoes, and rum is distilled from fermented sugarcane.
Assorted whiskeys are derived from fermented grain mashes; rye whiskey is from rye mash, and bourbon from corn mash. Brandy is distilled grape, peach or apricot wine. |
