what is the use of yeast to make alcohol?

Question

this is my science homework i'm in 2nd you and all answers will be apprecated

Answer 1

one of gods better ideas

Answer 2

Yeast is a bit like a fungus in that it is alive. It feeds on sugar and excretes (sorry about the word) alcohol. In beer malted barley is is composed of sugar-like compounds. The barley is mixed with warm water and yeast. The yeast consumes the sugar and produces alcohol and breeds more yeast. The excess yeast is the thick brown froth that you see on top of Guinness, which is still fermenting when sold. All other beers have the fermentation process halted (by having the yeast froth scraped off the top.

Answer 3

Fermentation is the process in which yeast breaks down sugar into alcohol and carbon dioxide. Yeast are tiny single-celled fungi that contain special enzymes responsible for this reaction.

The word equation for this process is:

Glucose + yeast alcohol + carbon dioxide

Carbon dioxide gas bubbles out of the fermenting solution into the air leaving a mixture of ethanol and water. It's important that no air is present or the yeast will produce ethanoic acid - the chemical found in vinegar.

Answer 4

dawleymou almost has it, but not quite. the correct answer is when yeast respires anaerobically (without air) it produces ethanol (alcohol) instead of carbon dioxide
(you need oxygen to produce a carbon dioxide molecule, if the yeast have no oxygen, they will by default make ethanol as a waste product instead).
in order to respire, the yeast needs a form of energy, such as the sugars naturally found in plant materials used to make beer, wine or cider. so put the yeast in with the sugary liquid, leave it in a warm place, make sure its in a sealed barrel to cut off air, and there you have it!
in breadmaking, where the yeast has access to air, it produces carbon dioxide, which form the bubbles in the dough that make bread rise. hope this helps.

its also interesting to note that yeast fermentation alone cannot create an alcoholic drink stronger than about a 12% wine, as a higher concentration of alcohol kills the yeast. this is why spirits have to be distilled.

Answer 5

Yeasts used to make mead are close to the baker's yeast and biologists do not necessarily make a difference between these yeasts which, although very close from a biology standpoint, are used for different purposes. Yet baker's yeast is not used to make alcohol. Baker's yeast produces alcohol and CO2 from starch contained in flour, Alcohol evaporates due to high baking temperature (higher than 400°F) and CO2 will form bubble, giving some volume to the bread.

To make drinks, one focuses mainly on alcohol and let CO2 go (except for the second fermentation of champagne). Although aims are different, the basic principle is the same.

Unlike grapes which have yeasts (on their surface), honey does not contain much yeast. A fermentation relying only on wild yeasts would require months to start and would not be reliable. F1 tells the story of « traditional method » rhubarb wine, that is without adding yeast. The wine had methanol (toxic) and acetaldehydes (15 times as powerful as ethanol to provoke drunkenness). The result could even be a coma even when the consumption was moderate. Therefore wine yeasts are generally added for more safety and control. Nitrogen-containing molecules are also added as well as vitamins for honey contains very little of them.

There are three important types of yeasts (from the point of view of their utilisation, not from the point of view of biologists' nomenclature): baker's yeast, beer yeast and wine yeast.

Some people (a minority) use beer yeast to make mead. They are of two kinds: ale (saccharomyces cerevisiae) and lager (saccharomyces uvarum).

Most wine yeasts are also saccharomyces cerevisiae (Champagne yeasts are saccharomyces bayanus). One distinguishes between white wine yeast and red wine yeast (and a few specialized yeast as Sherry yeast).

These yeasts come in two forms. 5 g packages of dry yeast (cheap) are sold by Lalvin (lallemandwine.com) and by Red star (redstaryeast.net/). White labs (whitelabs.com) and Wyeast (wyeastlab.com) sell their yeasts in liquid form (much more expensive but supposed to be purer). White labs commercializes a yeast dedicated to mead and Wyeast has two of them (dry and sweet) but there are not well distributed and so there are harder to find than usual wine yeasts.

Yeasts will give different flavors but they will also lead to different alcohol contents and different quantities of residual sugar. Some yeasts (not very numerous) will not ferment beyond 4 % of alcohol, others (bayanus for example) can reach around 35 proof. Some have a low attenuation (proportion of sugar transformed into alcohol): they leave a lot of sugar and the result is sweeter than with other yeasts. On the other hand, some yeasts (bayanus again -- Champagne yeasts) will lead to a dry mead, really dry. One has to take this into account when a yeast and a quantity of honey are to be chosen.

Anyway, after the half dozen years of recommended ageing, the difference between different yeasts will have died out [V2].

Answer 6

Yeast is part of the fermentation process. Did you know the white mist colour found on certain fruits like grapes contain yeast. some people say you can make wine without yeast, but i am unsure.

Answer 7

Yeast begins the fermentation process which ultimately results in alcohol.

Answer 8

Eliminate Yeast Infection Fast - http://YeastCured.uzaev.com/?dzRf

Answer 9

Yeast ferments. Ethanol is a product of fermentation.
Look up the word "fermentation" in your text, your dictionary,
or on the web.

Answer 10

http://en.wikipedia.org/wiki/Brewing Use this link to find all the answers you need. Basically yeast ferments grain or hops and produces alcohol as a by-product.

Answer 11

Sugar and yeast enzymes combine to make carbon dioxide and ethyl alcohol. Process shown here -

http://www.yobrew.co.uk/fermentation.php