Yeast Fermentation

Topics: Yeast, Beer, Carbon dioxide Pages: 3 (674 words) Published: March 13, 2013
tionStudent Name: Laura Scott
Student Number: C11356616
Lab Partners Name: Charlotte Weir
Experiment Name: Yeast Fermentation
Experiment Date: 2nd and 9th November 2011
Submission Date: 23rd November 2011

Yeast Fermentation

To allow for fermentation of the yeast, Saccharomyces Cerevisiae, in Grape and Apple juice.

Materials provided
Test-tube containing Grape juice and a Durham tube
Test-tube containing Apple juice and a Durham tube
Plate culture of the yeast, Saccharomyces Cerevisiae
Sterile swabs

As per manual

·Sediments of the cell sunk to the bottom of the test-tube. ·The Durham tube had risen to the top of the test-tube.
·There was a strong smell of alcohol from the fruit juice. ·Bubbles could be seen in the test-tube.

|Apple juice|Grape juice|

Comments and Conclusions
After close examination of the two test-tubes, it was clear that fermentation had taken place in both the Apple and Grape juice. Gas had been collected in both of the Durham tubes and had caused them to rise to the top of the test-tubes. There was also a strong smell of alcohol from both the juices now and the colour of the juices had changed slightly too, becoming a little bit darker than the colour of the juices before fermentation had occurred. The bubbles that were visible in the test-tubes were trapped CO2, the result of yeast fermenting sugars in the grape and apple juice. From all of the above we can definitely conclude that yeast fermentation occurred in both the Apple and Grape juice.

Fermentation is the conversion of sugar into an acid or an alcohol. It can also refer to the use of yeast to change sugar into alcohol. Fermentation occurs naturally in many different foods given the right conditions, and humans have intentionally made use of it for many thousands of years. Fermentation was first used to create alcoholic beverages such as wine and beer. The fermentation of...
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