Factors Affecting Fermentation

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 Steam inlet Nutrient inlet Water jacket

Temperature probe Ph probe

Cold water inlet Air inlet Cold water outlet Stirring paddles

Function Hot steam sterilizes the fermenter under high pressure. Allows the sterile nutrients to enter at the start. Circulates cold water to keep the temperature at the best level for growth. To adjust the temperature To adjust the ph levels. The contents can be adjusted by adding acid or alkali. To allow cold water to enter. Provides a source of oxygen To let water out (cycle) Mixes the contents, so the microorganisms can be exposed to the nutrients and keep the temperature

Harvesting outlet Filter

constant and even. To let the end product out to be packaged. 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 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 Control 6 Yes 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

Froth 7

6

6 5

Level of Froth (mm)

4

5 4

3 2

4

2

2

1

1 0

0

Conditions/Factors Glucose only

Acid

Alkali

Boiling water

Water Bath

Fridge

Control

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://chemistry.about.com/od/lecturenoteslab1/f/What-Is-Fermentation.htm

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/