Hungry Planet: What Is in the Foods the World Eats?

Hungry Planet: What is in the foods the world eats? http://abcnews.go.com/International/photos/hungry-planet-19126014/image-19126027

Purpose: What did you have for dinner last night? Did it help meet your body’s needs for energy and nutrients? Did you have enough to eat? How do you think your meal compares to meals eaten by people around the world? Everything you eat is composed of three major organic compounds: carbohydrates, proteins, and fats. In order to convert food into energy, the body must be able to break the food into these basic compounds and then further reduce them to the molecular level. The body can absorb food only when it is at the molecular level because it must be small enough to pass through cell membranes. What organic compounds are we digesting when we eat a typical American meal? We will use chemical indicators that change color when they react with certain kinds of organic compounds to test for their presence in foods from the U.S. and around the world.

Pre-Lab Indicator Info: Indicators (or reagents) are chemicals that change color (react) when combined with specific substances. Complete the following chart by reading the background section for each part of the lab. Indicator Substance Being Color of a Color of a (Reagent) Testing For (+) Result (-) Result Simple Sugar

Starch

Protein

Global Meal: Circle the meal at your lab station Global Meal A – North America/McDonald’s Happy Meal – cheese burger, fries, coke Global Meal B – Asia – Fish, Global Meal C – South America – Rice, Chicken, tortillas, Coke Global Meal D – Mediterranean – olives, All meals have been blended with the addition of water. A. Carbohydrate Tests— Monosaccharides – Simple Sugars Background: The building blocks of carbohydrates are sugars (monosaccharides). The simplest sugar is glucose which is used by cells as an energy source during cellular respiration. When Benedict’s Solution is added to a solution, and HEATED, if the substance contains sugar, the solution turns RED (or some color other than blue…green, yellow, orange, red). If the solution does not contain any simple sugars, then the solution remains BLUE after heating. (Warning—Benedicts solution is caustic and dangerous to the eyes. Wear goggles and be sure to wash your hands afterwards before touching your eyes.)

Procedure: 1. Plug in a hot plate and turn it on HIGH. 2. Create a hot water bath by filling a glass beaker LESS than ½ way with water and placing it on the hot plate. If the water begins to boil, lower that heat to LOW. 3. Flask neg control - Put 15 drops of water 4. Flask 2 (labeled mono 1) - Put 15 drops of the known glucose solution 5. Flask 3 (labeled mono 2) - Put 15 drops of the processed meal. 6. Add 30 drops of Benedicts solution into each test tube and swirl to mix. 7. Record the initial color of each test tube in the data table. 8. Put all test tubes in the hot water bath for several minutes and watch for a color change. (you may move on to do the next test while you wait for the solution to warm up) 9. WEARING A HEAT RESISTANT GLOVE, remove the hot beaker from the water bath. Allow all materials to COOL. 10. Record the final color of each test tube. If the color changed, you have a positive reaction (+) for sugar. If the color does not change, the reaction is negative (-).

Solution Color with Color with Sugar Results +/- Benedicts/ BEFORE Benedicts/ heating AFTER heating dH2O (-control)

Glucose (+control)

Global Meal B. Carbohydrate Tests—Starch test (Polysaccharide) Background: Starch is a polysaccharide stored by plants as an energy reserve. It is made by linking many glucose sugars together, but it will not react with Benedicts solution. Iodine is a yellowish-brown chemical that is used to test for the presence of starch. When Iodine is added to a substance that DOES contain starch, it instantly turns BLUISH-BLACK. If Iodine is added to a substance that does not contain starch, then it turns the substance the same yellowish-brown color of the iodine. (Warning—Iodine solution is caustic and dangerous to the eyes. Wear goggles and be sure to wash your hands afterwards before touching your eyes.)

Procedure: 1. Flask neg con (Labeled water) - Put 15 drops of water 2. Flask 1 (Labeled poly) - Put 15 drops of starch solution Solution Color BEFORE Color AFTER Starch Results +/- IODINE is added IODINE is added dH2O (-control)

Starch (+control)

Global Meal

3. Flask 2 (Labeled poly) - Put 15 drops of the processed meal 4. Record the initial colors of these samples in the BEFORE column of the data table. 5. Add 3 drops of iodine to each of the 3 test tubes and swirl to mix 6. Observe the test tubes and record the colors in the ‘AFTER’ section of the data table. If the iodine stays yellowish-brown, the reaction is negative for starch. If it turns bluish-black, it is positive for starch. 7. After this test is complete and you have recorded your data, rinse out each flask in the sink C. Protein test Background: The building blocks of proteins are amino acids. In order for your body to manufacture the proteins it needs, the proteins eaten in the diet must be broken down into amino acids ready to reassemble. In humans, the digestion of proteins begins in the stomach where hydrochloric acid and the enzyme pepsin are present. BIURET is a light blue chemical that is used to identify the presence of protein. When Biuret is added to a solution that does contain protein, it instantly turns the substance LAVENDER (light purple). If Biuret is added to a substance that does not contain protein, it turns the substance the same light blue color of the Biuret. (Warning—Biuret solution is caustic and dangerous to the eyes. Wear goggles and be sure to wash your hands afterwards before touching your eyes.)

Procedure: 1. Flask neg con (labeled water) - Put 15 drops of water 2. Flask 1 (Labeled protein) - Put 15 drops of albumin protein 3. Flask 2 (Labeled protein) - Put 15 drops of the processed meal 4. Record the initial colors of these samples in the BEFORE column of the data table. 5. Add 3 drops of BIURET to each of the 3 test tubes and swirl to mix 6. Observe the test tubes and record the colors in the ‘AFTER’ section of the data table. If the Biuret stays light blue, the reaction is negative for protein. If it turns lavender, it is positive for protein. **This is the hardest to test to see! Hold a piece of white paper behind the three test tubes side-by-side. COMPARE!

Solution Color BEFORE Color AFTER BIURET Protein Results +/- BIURET added added dH2O (-control)

Albumin Protein (+control) Global Meal 4. Fat Content Background: Fats are important to your body because they are used to make up part of the cell membrane. In order to test for the presence of lipids, a substance is rubbed on a brown paper towel or a paper bag. If the substance leaves a see-through spot after it is dry, then a lipid is present. If there is no see through spot left behind after it dries, then there is no lipid present. 1. Cut a brown paper bag into 5 squares small enough to fit on the data table. Write the name of each substance below on the 5 squares: - Water - Oil - French fry - Bun/Bread - Rice 2. Dip a toothpick into the water. Rub the toothpick with the water on the square labeled ‘water.’ Blot dry and let sit. 3. Dip a toothpick into the oil. Rub the toothpick with the oil on the square labeled ‘oil.’ Blot dry and let sit. 4. RUB a French fry on the ‘french fry’ square. 5. RUB the Bun/bread on the ‘bun/bread’ square 6. Observe the spot on each square by holding it up to the light. Record if there is a see through spot on the area or not in the data table. Substance See through spot? Lipid? (+/-) (yes or no) Oil (+ control) Water (- control) French Fry Bun

Hungry World Summary (Answer in complete sentences or plan to do it over!) 1. There were two control groups in each of these tests. Why did we need to have both a positive and a negative control?

2. Did your meal contain sugar? How do you know? If so, what part or parts of the meal might it have come from? 3. Did your meal contain starch? How do you know? If so, what part or parts of the meal might it have come from?

4. Did your meal contain protein? How do you know? If so, what part or parts of the meal might it have come from?

6. Compare the results from the meal you tested with the meals from other groups: Meal: Sugar Present? (+/-) Starch Present? (+/-) Protein Present? (+/-) A - McDonalds B - Asia C – South America D. Mediterranean

7. Do you think that Americans eat better than people in other countries, or just more? Explain your answer.