Investigating The Fermentation of Yeast

Authors Avatar

Matthew Attwood

8/12/97

Investigating The Fermentation of Yeast

I am going to investigate the fermentation of yeast with the use of liquid glucose as food.

Background on Yeast 

        Yeast cells are microscopic, one-celled fungi which are important for their ability to ferment carbohydrates in various substances. Yeasts are widespread in nature. They are found in the soil and on plants. Most yeasts used by man belong to the branch of living organisms called Saccharomyces. Those known as brewers’ yeasts are strains of Saccharomyces cerevisiae.

        Yeasts are well know for the making of bread and wine. Today they are used industrially in a large range of fermentation processes;

  • medicinally, as a source of B-complex vitamins and thiamine
  • as a stage in the production of various antibiotics and steroid hormones
  • as animal feed and foodstuff for humans.

        A yeast-like fungus is a source of riboflavin (vitamin B2) which is good for the skin.  Fungi are also used to produce Roquefort cheese and to ripen Camembert cheese.

        Yeast cultures are grown in a medium of sugars, nitrogen sources, minerals, and water. The final product may take the form of dried yeast cells, or the yeast may be pressed into cakes with some starchy material. When a batch of yeast for baking, medicinal, or food purposes is made, the stuff in which the yeast was grown is thrown away. In the making of wines, beers, spirits and industrial alcohol, however, it is the fermented liquid which you want and the yeast itself is waste or is used for animal feed. Fermentation of glucose by yeast produces ethyl alcohol and carbon dioxide.

Some Information On Glucose

Glucose, or monosaccharide sugar as it is sometimes known, has the chemical composition C6H12O6. You find it in honey and the juices of many fruits; the alternative name grape sugar comes from the presence of glucose in grapes. Glucose is a normal constituent of the blood of animals.

Glucose is a white crystalline solid but is less sweet than ordinary table sugar.

Glucose is formed from many carbohydrates, including sucrose, maltose, cellulose, starch, and glycogen.  Glucose is made industrially by the hydrolysis of starch under the influence of dilute acid or, more commonly, under that of enzymes. It is chiefly used as a sweetening agent in the food-processing industries. It is also used in tanning, in dye baths, and in medicine for treating dehydration and for intravenous feeding.


Explanation of the experiment

Join now!

I am going to set up a simple experiment to see how the fermentation of yeast develops at room temperature.  I am going to make use of the fact, already mentioned above, that when fermentation takes place a gas, Carbon Dioxide (CO2), is given off as a waste product.  When the fermentation is strong more gas will be made than when the fermentation is weak.  I do not need to know exactly how much gas is produced - I will only need to be able to judge if more or less is being given off.

Because there is limited ...

This is a preview of the whole essay