• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month
  1. 1
  2. 2
  3. 3
  4. 4
  5. 5
  6. 6
  7. 7
  8. 8
  9. 9
  10. 10
  11. 11
  12. 12

Fermentation of Yeast

Extracts from this document...


Stephanie Clayton- Fermentation of Yeast What is Yeast? *A single-cell fungi that form masses of minute circular or oval cells by budding. *When placed in a sugar solution the cells multiply and convert the sugar into ethanol and carbon dioxide. * Yeast are used as fermenting agents in baking, brewing, and making of wine and spirits. *There are lots of different varieties of yeast that can be used for industrial purposes and simply in the home. *Yeast grows wherever there is suitable food, most commonly found wherever sugar occurs. *The scientific name for yeast is 'saccharomyces' it means 'sugar-fungi'. *For many years yeast has been used to ferment the sugars in rice and barley to produce beer, and the sugar in grapes to make wine. *Yeast is also added to dough, which ferments the sugar in the dough to produce carbon dioxide, which causes the dough to rise and form bread. *When yeast is given food the cells grow and multiply, the diagram below shows a single-cell from a yeast plant: *Yeast does not need oxygen to survive. *The equation for fermentation is: Glucose = ethanol + carbon dioxide *If yeast is exposed to yeast it makes less ethanol and grows at a much slower rate. *If there is a good supply of food, a suitable temperature, and water, budding occurs at a faster rate. ...read more.


As in some cases the gas collected can be different therefore collecting the gas at one particular temperature means you will end up will a more accurate sample of gas. The measurements are taken after 2 minutes after the temperature has been reached: 1 2 3 30 1ml no more gas produced no more gas produced 40 6.8ml 4.2ml 8ml 50 10ml + 6ml 2ml 60 8ml 1ml 2ml Graphs to show the results are on the next few pages Results Conclusion My aim at the beginning of this investigation was to find out the effects of temperature in the process of fermentation. My prediction was that when I reached the temperature of 40 the amount of carbon dioxide produced would be at its greatest. From the final set of results I gathered I found that this confirmed my earlier predictions. In my prediction I also stated that after 40 the enzymes in the yeast would be 'denatured' because the enzymes had passed their optimum temperature, therefore less gas would be produced. This is also shown clearly in my result table. During my investigation each temperature I measured the amount of gas at, I took three results. My purpose was to establish an accurate measurement of carbon dioxide. ...read more.


There are 4 main stages in the yeast growth cycle: Lag phase Rapid growth Growth slowing Population constant In the investigation my aim was to get the yeast into the two middle stages of rapid growth and growth slowing. As the fermentation process reaches a certain point it stops. This is because the enzyme produces carbon dioxide and alcohol, the alcohol acts as a poison on the yeast population and kills the yeast. If I were to do any extension work concerning this investigation I would look into the optimum temperature of the enzymes. I would find a method to try and test the temperature around 40 to see how much carbon dioxide is produced just before and after to see how the enzymes deteriorate after they have reached their optimum temperature. You could also look at the gases that were produced along with the carbon dioxide collected in the first two sets of results. I would have to research how I could test to see what the gases were, I would then be able to distinguish what was carbon dioxide and what wasn't at the particular temperature. Also if I were to investigate further I could use different types of sugar or yeast. These are all different paths I could look into. There are many other ways you could take this investigation but from this aspect of how temperature affects fermentation has been very successful. From taking it further I could only learn more about fermentation. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our AS and A Level Molecules & Cells section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related AS and A Level Molecules & Cells essays

  1. Investigation to find the effect of glucose concentration on fermentation of yeast.

    produced I used phenolphthalein to see the color change as an alternative. This was found to be more accurate as I could see the colour change-taking place, and practically it was easier to set up. * It was found that the predictions on the rate at which the substrates were respired were correct.

  2. The investigation to find the effect of glucose concentration on fermentation of yeast.

    The amount of yeast will have an effect on the rate of reaction, as the yeast contains the enzyme (zymase), so if I increased the amount of yeast the rate of reaction will take place in a different way it could be both slower and faster.

  1. Investigation into the Effect of Temperature on the Rate of Fermentation by Yeast.

    Also, at 15 oC, there will be no carbon dioxide produced, and the gradient of the graph will be zero, because there will be no activity taking place, and therefore, no cell respiration taking place. From Fig 1, we could predict that there will be some production of CO2 at

  2. Catalyse Investigation

    To be able to do this, intermediate enzyme concentrations would have to be measured so that the shape of the graph would be more exact. Suggestions and Improvements - To create a more accurate experiment in the future, several precautions or alterations can be made: � Instead of using potato

  1. Production of Alcohol by Fermentation

    and the tables could become sticky so that is something that you should definitely look out for, and also place your equipment back to their places. Method/ Procedure: 1. When beginning your experiment you must firstly gather your equipment and set up your working area, when this is done you

  2. Investigating the Effect of Temperature on the Fermentation of Yeast

    be able to accommodate for its specific target molecule, as the active sites, and consequently its helix structure, will have changed from their unique shape. This is a non-reversible action and is called denaturation. The common analogy for this reaction is 'the lock and key'.

  1. An Investigation to Show that Yeast Can Ferment Some Types of Sugars Quicker than ...

    This is because the enzyme will not be able to break down or create bonds, as the substrate does not fit. Yeasts are single celled fungi. Yeasts whose ideal substrates are sugars are called Saccharomyces. Many saccharomyces are facultative anaerobes which means they can respire anaerobically (without oxygen).

  2. As a culture of yeast is merged with solution of sugar, a reaction called ...

    The volume of the yeast mixture should also be used in the same quantity throughout the investigation. The considerate quantity is about 2cm3, considering the size of the test tubes themselves. The mixture should be gently shaken to blend the solution and the culture together, as the culture tends to settle at the bottom over a certain time.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work