Many yeasts are anaerobic organisms or can survive in oxygen – absent environments during which time they ”switch” to a process called anaerobic respiration for the purpose of producing food by breaking down carbohydrates. The final products of the anaerobic respiration are nutrients, ethanol and carbon – dioxyde. Whats more, different types of carbohydrates release various amounts of energy during fermentation. The amount of CO2 released is directly proportionate to the quantity of energy gained by the process.
Which 6 – carbon sugar would be most suitable for yeast fermentation by energy – efficiency?
In our opinion, glucose posesses the highest energy potential, due to its structure and the locations of its OH groups.
Types of sugars used
Temperature of bath water
Concentration of sugars
Quantity and type of yeast
Table of variables
* yeast suspension
* 2% of glucose, sorbose, fructose and galactose solution
* distilled water
* 12 x 10cm3 syringes
* 12 test tubes plus corks
* 250 ml beaker
* hot water at 40ï¿½C
* 10mL measuring cylinder
* distilled water
* stop water
1. Pour 5 cm3 yeast solution mixture into a test tube
2. Add 5 cm3 of fructose into the test tube
3. Shake the test tube to mix the solutions
4. Put the stopper with syringe into a test tube
5. Place the tube containing the syringe into the beaker with water bath at 40ï¿½C
6. Measure the CO2 for every 5 min
7. Repeat the procedure with the other solutions
8. Record the time you begin the experiment
Data collection and processing
Raw data obtained as a result of the experiment is exibited in Table 1 and that data is also presented in Graph 1.
Conclusion and evaluation
From the data obtained we can see that the highest emission of carbon – dioxyde was a result of glucose fermentation and therefore we can conclude that this sugar would be the optimal choice for maximizing energy efficiency of anaerobic respiration.
There are, however a couple of things that may make the final results of the experiment unvalid, and that is the inconsistency and subjectivity in the evaluation of the time interval between pushing the plunger inside and letting it com back, and the posiible leakages around the wooden corks, as well as their stability inside the test tubes.