Fermentation Lab

Lesson: Ruminant Digestion Activity: Fermentation Lab Student Name: ______________________________ Date: _______________ Period: _______________ Strange Brew – A Fermentation Demonstration Read the Background Information, Purpose, and Procedure, and answer the pre-lab questions below. When you have finished answering the questions, have your teacher sign off on your paper! Background Information Living things are constantly consuming glucose (from our food) to produce energy for themselves through the process of Cellular Respiration. Cellular Respiration is the breakdown of sugar (glucose) to form ATP (a form of energy for an organism). There are two types of respiration: aerobic (requiring oxygen) and anaerobic (without oxygen) also known as fermentation. Aerobic Cellular Respiration: C6H12O6 (Glucose) + 6O2 → 6CO2 + 6H20 + 38ATP Anaerobic Respiration (Fermentation): C6H12O6 (Glucose) → CO2 + CH3CH2OH (ethanol) + 2ATP Yeast cells (a type of fungus) obtain energy from glucose (sugar) by a specific anaerobic process called fermentation. There are two types of fermentation, lactic acid fermentation (which occurs in muscle cells when they are oxygen deprived), and alcoholic fermentation, which is involved in the making of food products. Alcoholic fermentation begins after glucose diffuses into the yeast cell. The glucose is broken down into 2, 3 carbon molecules called pyruvic acid. The pyruvic acid is then converted to CO2, ethanol, and energy for the yeast cell. Don't get excited, students, there is very little ethanol in this root beer ☺ Fermentation is used to make a variety of food products, including the making of beer, wine, bread, cheese, yogurt, and sauerkraut. The CO2 from fermentation also makes baked good, such as breads, rise. It is the carbon dioxide produced by the yeasts that give root beer its "fizz." This fizz is produced in store bought root beer by a carbonation machine that forces carbon dioxide gas into the root beer mixture, without the aid of our little yeast friends. History of Root Beer: Root beer was made by our forefathers by soaking Sasafras (a type of tree) root in water, and adding sugar and yeast (yeast for carbonation). In the early 1900's however, scientists discovered that safrole, a chemical found in Sassafras root, was a carcinogen (which means it is a cancer causing agent.) Now, a mixture of other herbs and spices makes up "root beer extract" which is what we now use to make homemade root beer. Lesson: Ruminant Digestion Activity: Fermentation Lab Student Name: ______________________________ Date: _______________ Period: _______________ Materials: • Clean, empty, 500mL plastic bottles + caps • Large Beaker • Funnel • Stirring rod • Warm water (40 – 45 oC) • Active dry yeast • Root beer extract • Sugar • Thermometer • Graduated cylinder • Electric balance • Metric Ruler Procedure: 1. Make a label out of plain white paper, and put your names on it. Tape the label to the bottle. 2. Measure 250 mL of warm water with a graduated cylinder and pour the water into your bottle. 3. Measure 0.2 grams of yeast using the balance and place into your bottle of warm water. Let stand for 5 minutes. Being in warm water activates the yeasts (they like warmer temperatures), and the water rehydrates them from being dried out 4. Measure 50 grams of sugar and add to your bottle (after it has set for 5 minutes). 5. Measure 2.5 mL of root beer extract using a graduated cylinder and add this to your bottle. 6. Use the stirring rod and mix the contents well; then shake with the cap on. 7. Add more warm water until the water level is approximately 4 centimeters from the top of the bottle. 8. Tightly cap your bottle and lay it on its side in the sink. 9. Repeat steps with a second bottle omitting step 2. We will not add the yeast mixture to this bottle; this will be our experimental control. 10. Age root beer for 3 or 4 days in a warm, dark place. Then store in a cool, dark place for 2 more days. Refrigeration will stop the fermentation process and kill the yeast. Total aging of at least one week is recommended. Two weeks will improve the flavor. Be sure to check the bottles every day for tightness, if they get too pressurized, they will explode. Never use glass bottles! 11. Chill root beer and taste. Students may be surprised at how different this root beer is from store bought root beer. Lesson: Ruminant Digestion Activity: Fermentation Lab Student Name: ______________________________ Date: _______________ Period: _______________ *Pre-Lab Questions: 1. In your own words, define fermentation. ________________________________________________________________________ ________________________________________________________________________ 2. List the ingredients needed to make root beer. ________________________________________________________________________ ________________________________________________________________________ 3. Why is yeast necessary in this experiment? ________________________________________________________________________ ________________________________________________________________________ 4. Why is sugar necessary? ________________________________________________________________________ ________________________________________________________________________ 5. What ruminant organ do the bottles in this lab represent? Why? (Refer to PowerPoint presentation covering structure and function of the digestive system.) ________________________________________________________________________ ________________________________________________________________________ 6. Why did we put the yeasts in the warm water for 5 minutes? ________________________________________________________________________ ________________________________________________________________________ Experimental Set-up: Making Root Beer through Fermentation Lab Experimental Question: (The question your experiment will attempt to answer) Hypothesis (Use the “If___ then____ because______.” format) ________________________________________________________________________ ________________________________________________________________________ Independent Variable: (manipulated variable) Dependent Variable: (responding variable) Treatment Group Lesson: Ruminant Digestion Activity: Fermentation Lab Student Name: ______________________________ Date: _______________ Period: _______________ Experimental Control Group ________________________________________________ Controlled Variables: (Factors in the experiment that are not allowed to change) List 5. ________________________________________________________________________ ________________________________________________________________________ Post-Lab Questions: 1. Describe the taste and appearance of the root beer that did not have yeast added to it and was not fermented. How is it different from the root beer when we first bottled it? __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ 2. Describe the taste and appearance of the root beer that had yeast added to it and was fermented. How is it different from the root beer when we first bottled it? __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ 3. Was your hypothesis supported or not supported by the experimental data? __________________________________________________________________ 4. Explain how the root beer came to be carbonated. __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ 5. Why would it have been dangerous to use glass bottles instead of plastic? What product of fermentation would have caused this? __________________________________________________________________ __________________________________________________________________ Lesson: Ruminant Digestion Activity: Fermentation Lab Student Name: ______________________________ Date: _______________ Period: _______________ 6. Explain how the fermentation process demonstrated in lab is similar to the process that occurs in the rumen of a ruminant animal (cow, sheep, giraffe, etc…). __________________________________________________________________ __________________________________________________________________ __________________________________________________________________ __________________________________________________________________