Introduction Carbohydrates, proteins, and fats are all essential nutrients. We cannot manufacture these nutrients so we must obtain them from our environment.
Introduction In this lab, with the use of indicators as chemical detection tools, you will analyze a variety of foods for the presence of nutrients. Detection is based upon observing a chemical change that takes place most often a change in color.
Objective Identify the presence of major nutrients such as simple carbohydrates (glucose), complex carbohydrates (starch), protein and fat in common foods.
Do NOW • Take out your notes about macromolecules and answer the questions. • 1. What are some things that we observed on marshmallow, salt, vinegar, and beans? • 2. What are macromolecules?
A. What are Macromolecules? • All living things contain organic macromolecules: lipids, proteins, carbohydrates, and nucleic acids. Can you name some examples?
What are Macromolecules? • Each of these macromolecule contains building blocks:
DO NOW • 1. What are the building blocks of these macromolecules? • Carbohydrate: • Protein: • 2. What is the indicator? • 3. How do we know if we have something that indicator is looking for?
C. What is an indicator? • Indicators are chemical compounds used to detect the presence of certain compounds. • It usually makes an observable change when the substance is present.
C. What is an indicator? • Observable changes could be a color change, precipitate formation, bubble formation, temperature change, or other measurable quality.
Test for Simple CarbohydratesBenedict’s solution • Benedict's solution is a chemical indicator for simple sugars such as glucose: C6H12O6. • Aqua blue: negative test; yellow/green/brick red, etc.: positive test
Test for Simple CarbohydratesBenedict’s solution • Unlike some other indicators, Benedict’s solution does not work at room temperature - it must be heated first.
Test for Complex CarbohydratesLugol’s solution • IKI solution (Iodine Potassium Iodine) color change = blue to black
Test for Complex CarbohydratesLugol’s Iodine Solution • Iodine solution is an indicator for a molecule called starch. • Starch is a huge molecule made up of hundreds of simple sugar molecules (such as glucose) connected to each other.
Test for Protein (amino acids)Biuret solution • Biuret solution dark violet blue to pinkish purple
Question Why didn’t the test tube containing starch change colors? Because Starch is NOT a simple sugar; Benedict’s only tests for simple sugars.
ProcedureSimple carbohydrate • Add 5ml distilled H2O using pipette to test tube • Add 1ml of food sample to test tube • Add 20 drops of Benedict solution • Place test tube in a hot water bath for 10 minutes.
ProcedureComplex carbohydrate • Add 5ml distilled H2O using pipette to test tube • Add 1ml of food sample to test tube • Add 20 drops of IKI solution
ProcedureProtein (amino acids) • Add 5ml distilled H2O using pipette to test tube • Add 1ml of food sample to test tube • Add 20 drops of Biuret solution
ProcedureFats (lipids) • Add 5ml distilled H2O using pipette to test tube • Add 1ml of food sample to test tube • Add 20 drops of Sudan IV
LAB SAFETY and CLEAN UP NO EDIBLE products in lab WEAR safety goggles and apron at all times THOROUGHLY CLEAN lab area and equipment