Investigating factors that affect fermentation Introduction
Fermentation is a metabolic process in which an organism converts a carbohydrate, such as starch or sugar into alcohol or and acid. It undergoes anaerobic respiration. Anaerobic respiration is respiration which doesn’t require oxygen. However, it also means that the glucose used for respiration to take place, isn’t completely broken down and therefore doesn’t release as much energy as aerobic respiration would. Anaerobic respiration also gives different products in comparison to aerobic. For example, aerobic produces carbon dioxide, water vapour and energy whilst
anaerobic only produces lactic acid, which is basically a molecule of glucose broken into half. Anaerobic gives much less energy in comparison to aerobic as it doesn’t break as many bonds.
Equation: glucose ethanol + carbon dioxide. Conditions inside the fermenter:
1. Before being filled with nutrients and culture, it’s cleaned by aseptic precautions through steam (where the pressure is high), which kills any microorganisms to prevent any contamination and so no residue is left. 2. Since its aerobic respiration, there has to be a supply of oxygen.
3. The ph and temperature levels have to be contained so it can reach its optimum level of production.
4. Stirring so the nutrients are evenly distributed.
TABLE 1: Parts of the Fermenter: COPIED FROM THE TEXTBOOK
Structure Function
Steam inlet Hot steam sterilizes the fermenter
under high pressure.
Nutrient inlet Allows the sterile nutrients to enter at the start.
Water jacket Circulates cold water to keep the
temperature at the best level for growth.
Temperature probe To adjust the temperature
Ph probe To adjust the ph levels. The contents
can be adjusted by adding acid or alkali.
Cold water inlet To allow cold water to enter.
Air inlet Provides a source of oxygen
Cold water outlet To let water out (cycle)
Stirring paddles Mixes the contents, so the
microorganisms can be exposed to the nutrients and keep the temperature
constant and even.
Harvesting outlet To let the end product out to be packaged.
Filter Stops microorganisms from entering.
Making Beer:
1. First of all the barley seed are germinated, which then produces amylase (enzyme).
2. Then the seeds are killed by heating without destroying the enzymes, and then dried to make malt.
3. It’s then mixed with hot water in a mash, where the amylase is breaks down the starch to produce maltose and a sweet liquid, which is then boiled to stop the enzymes working (by causing the enzymes to denature) and then filtered. 4. Next, hops are added onto the product so it can prevent bacteria from
growing and to make the taste bitter.
5. Also yeast is added to ferment the sugars, where it uses the oxygen causing the sugar anaerobically respire. This produces beer.
6. The beer is centrifuged and filtered. 7. Finally it’s put into casks or barrels. Aim: to see what factors affect fermentation
Hypothesis: The factor that will produce more alcohol would be the tube in the water bath because the temperature (35 degrees) it is the optimum temperature so the enzymes would be efficiently break down the glucose and wouldn’t denatured. The factor that would produce the least would be the tube in the fridge because there would be any energy for the enzymes to break down the glucose as there is no heat and the tube in hot water would to because the enzymes would denature because of the high temperature.
Equipment: Test tube Balloons Glucose solution Yeast hydrochloric acid sodium hydroxide
Water bath set at 35 degrees
Fridge
Boiling water set at 100 degrees
Table spoon
Pipette Method
1. Grab 7 test tubes and place 2cm3 worth of sugar solution and yeast 2. In 1 of the test tubes, keep everything the same and keep it at room
temperature, so it doesn’t contain water
3. In 1 of the test tubes, add 2cm3 of water to the test tube so it is the control 4. In another 1 of the test tubes, add hydrochloric acid and add 2cm3 of water
5. In another add 2cm3 of sodium hydroxide and add 2cm3 of water 6. In another add 4cm3 of boiling hot water
7. In another add 2cm3 of water and place it in a freezer 8. In another add 2cm3 of water and place it in a water bath 9. Measure the level of froth
10.Write down the results
RESULTS:
TABLE 2: the level of froth created by each condition and whether or not CO2 was collected
Graph 1: Level of froth from each test tube
Condition Level of Froth (mm) Any CO2 collected
Water Bath 5 Yes
Boiling Water 4 No
Fridge 0 No
Alkali 2 Yes
Acid 2 Yes
Glucose only 4 Yes
0 1 2 3 4 5 6 7 4 2 2 6 4 5 0 1
Froth
Glucose only Acid Alkali Control Boiling water Water Bath Fridge
Conditions/Factors Level of Froth (mm)
Discussion:
When looking at the results the factor that produced the most froth and produced CO2 was the Acid (hydrochloric acid) and the Water Bath and the factor that didn’t produce any froth and CO2 was water and fridge. This approves my hypothesis, “The factor that will produce more alcohol would be the tube in the water bath because the temperature (35 degrees) it is the optimum temperature so the enzymes would be efficiently break down the glucose and wouldn’t denatured. The factor that would produce the least would be the tube in the fridge because there would be any energy for the enzymes to break down the glucose as there is no heat and the tube in hot water would to because the enzymes would denature because of the high temperature”. The glucose had a froth level of 4mm which was expected as the temperature and ph was constant and the alkali had a froth level of 3mm. The surprising result was the boiling water because it a froth level of 4mm when it was supposed to have a level of 0 as the enzymes would have denatured as its past is optimum temperature, so it’s unable to break down the glucose.
Limitations:
When pouring the products it we could’ve have put too much or little. Another thing is that the “boiling” hot water wasn’t immediately added to the solution. This
allowed the water to cool before it was added to the solution. This might have therefore given us inaccurate results. Also when measuring the level of froth it could’ve been inaccurate as we were measuring it at eye level on a curved surface. References:
http://www.bbc.co.uk/bitesize/standard/chemistry/plasticsandothermaterials/carboh ydrates/revision/6/
http://www.bbc.co.uk/education/guides/zfydmp3/revision/3
http://www.bbc.co.uk/schools/gcsebitesize/science/triple_edexcel/using_biology/biot echnology/revision/1/
