Research question:How are the concentrations of sugar affect the amount of alcohol produced afterfermentation of yeast?Backgroundinformation:Anaerobic respiration in yeast is known as fermentation.
Yeastis a fungal microorganism that remains a common component of modern wine andbread manufacture. Fermentation is the scientific process that yeast metabolizessugars and releases alcohol and carbon dioxide. Yeast contains enzymes that catalyze thebreakdown of glucose to ethanol and carbon dioxide. Fruits can also use to made alcohol (ethanol) instead of pureglucose when the incomplete level of oxygen occurs. Alcohol can be made fromany fruits that contend starch or sugar.
In this experiment we will be usingpineapple juice as sugar for fermentation. Pineapple contains sucrose, glucose and fructose, whichcan undergo fermentation. Also pineapple is really easy to extract its juicesince it really juicy, therefore, it doesn’t need to add water when blending itthat make the concentration of pineapple juice more concentrated.
Cell respiration involves the production of ATP using energyreleased by the oxidation of glucose and the first stage of cell respirationfor glucose as a substance is a metabolic path way called glycolysis. Glucoseis partially oxidized in the pathway and a small amount of ATP is produced. Theglycolysis process can be achieved without using oxygen therefore theglycolysis can form part of both aerobic and anaerobic respiration. Glycolysisconverts one glucose into two pyruvates. Two ATP molecules are used per glucoseand four are produced so there is a net yield of two ATP molecules. This is asmall yield of ATP per glucose, but it can be achieved without the use of anyoxygen, which is anaerobic respiration. Two NADs are also converted into tworeduced NADs. The pyruvates form glycolysis can be ferment to form ethanol andcarbon dioxide and this process occur without using oxygen.
As shown in thechemical equation below: https://www.emaze.com/@AFRRFLOC/Cellular-Respiration After fermentation, the solution will contain excess yeastand won’t be a pure ethanol; therefore, extraction will be required by theprocess call distillation. Distillation is the method that separates liquidfrom a mixture of liquid by using the different boiling point of the liquid.Liquids have a different boiling points therefore they vaporize at differenttemperature. Distillation is commonly used to separate ethanol that has boilingpoint at 78.A small change of the temperature can affect the product that produced.
Thenthe alcohol produced can be measure by using hydrometer. Hydrometer uses tomeasure a characteristic of liquid such as the specificgravity (weight per unit volume compared with water). In thisexperiment the data collected need to be calibrate to percentage by using ,start gravity is the pineapple juice before ferment and final gravity ispineapple juice after ferment and distilled to get a ethanol.Independent variable:Concentration of pineapple juice (100%, 80%, 60%, 40%, 20%)Dependent variable:The amount of alcohol that produced (in %)Controlled variables: Controlled variables Importance Control methods Amount of yeast Yeast has an enzyme called zymase and this catalyses the fermentation process. The more amount of yeast the faster reaction, which might impact the amount of alcohol, produce in specific time. Using electronic balance to measure the amount of 5 grams of yeast because electronic balance is really accurate, therefore, amount of yeast added will be likely the same. Amount of pineapple juice The amount of pineapple juice is mean the amount of sugar, which effect the amount of ethanol produced.
Yeast consumes sugar to release ethanol and carbon dioxide therefore the more sugar the more ethanol produced. Use the same amount of pineapple juice in every concentration to keep the independent variable as a concentration of pineapple juice. Pineapple Different pineapple might give different amount of sugar. Some pineapple can be sweeter than another. Use pineapple juice from the same pineapples in every trials and concentrations. Amount of fermentation time The longer the fermentation the higher amount of ethanol produced. After 3 days of fermentation, all fermented pineapple juice need to be distil within the same day otherwise the experiment result will not be accurate Temperature The temperature has an affect on rate of reaction and amount of ethanol produced.
The high the temperature the faster the rate as well as the amount of ethanol produces. During the fermentation store all the solution in the same place at room temperature. During distillation is really important to keep constant. The change in temperature can affects the product of distillation because all liquids have their own boiling point and the increase and decrease in temperature might vaporize the liquid that we don’t want. It really hard to keep the temperature constant throughout the experiment, therefore, keep the temperature in the range of 77-82 which is close to 78 of ethanol boiling point but does not reach others liquids boiling points. Hypothesis:The more concentrated pineapple juice, the more sugarcontained. In the higher concentrated solution, the amount of ethanol willproduced more due to the higher rate of fermentation of yeast.Apparatus:(Uncertainty)1.
2 pineapples2. Knife and chopping board3. Blender4. Filtered5. 300 mL Beagers 6.
1000 mL Beager 7. Yeast power 8. 100 mL measuring cylinder 9. Electronic balance10. Stirringrod11. Hydrometer12.
Parafilm13. Icebath14. Thermometer15.
Distilledwater16. Stirringrod17. DistillationtoolsMethod:1. Peal and cut pineapple into small pieces2. Put all the pineapple in the blender and blendit until the pineapple become puree then put it in the filtered to percolatethe pineapple garbage and store the pineapple juice in 1000 mL beager.
Makesure that the pineapple juice doesn’t have anything in it. 3. Dilute the pineapple juice into 5 concentrationsby adding the distilled water using the measuring cylinder to measure and mixit together in amount that shown in a table below: Concentrations Pineapple juice (mL) Distilled water (mL) 100% 600 0 80% 480 120 60% 360 240 40% 240 360 20% 120 480 *mix the pineapplr juice and distilled water in 300 mLbeager.4. Take a sample of pineapple juice in eachconcentration before add the yeast, place the hydrometer and record thestarting gravity.5. Use measuring cylinder to measure 200 mL ofpineapple juice for 5 concentrations using 100 mL measuring cylinder and pourin the 5 different 300 mL beagers.
6. Weigh 5 grams of yeast power using electronicbalance with electronic balance and pour 5 grams of yeast in each beagers foreach concentration and make sure that the yeast power goes in at the same time.7.
Mix the yeast and pineapple juice with thestirring rod until the solution completely mixed.8. Cover the beagers with parafilm to prevent othersubstances to fall in and make a small hole on the film for the gas produced(carbon dioxide gas) to move out and prevent the burst of high pressure gas9. Keep the beagers close for 3 days to let thefermentation begins10. After3 days, stir the solution and pour the solution in the distillation flask.
Makesure that the solution doesn’t go over two thirds of the flask to prevent thesolution that might propel into the condenser, compromising the purity of thedistillate.11. Place the flask in the thermowellheat source and set up the distillation as the diagram below: 12. Setthe temperature and keep in constant at 77-82 (ethanol boils at 78 )13. When the product of distillation reaches 100mL in receiving flask remove the heat source.14.
Repeat the process of distillation for allconcentrations and all concentrations in the same trial need to distil in thesame day.15. Repeatsteps 4-13 for trial 2 and trial 3. 16.
Place all the distilled solutions in the icebath and wait until the temperature lower and reach 15 (temperature that hydrometer work best)17. https://contrastique.wordpress.com/tag/hydrometer/ Place the hydrometer in each solution and record the finalgravity.
18. All the solutions, chemical, and waste fromthe lab can pour it in the sink since it’s not toxic and won’t have any effectto the environment.Observation:Data: Concentration of pineapple juice (%) Starting gravity Final gravity Trial 1 Trial 2 Trial 3 20 1.011 1.003 1.002 1.004 40 1.014 1.000 1.001 1.002 60 1.017 0.998 0.999 1.000 80 1.019 0.997 0.997 0.998 100 1.021 0.995 0.996 0.996 Calculation the percentage of ethanol using equation: =1.031%Uncertainty:Uncertainty of starting gravity = Uncertainty of final gravity = Total uncertainty = 0.001 +0.001 Concentration of pineapple juice (%) % Of ethanol Trial 1 Trial 2 Trial 3 20 1.031 1.160 0.902 40 1.804 1.675 1.546 60 2.448 2.320 2.191 80 2.835 2.835 2.706 100 3.351 3.222 3.222 Calculate the average of % ofethanol: Concentration of pineapple juice (%) % Of ethanol 20 1.031 40 1.675 60 2.320 80 2.792 100 3.265