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IDENTIFYING MACROMOLECULES IN FOOD LAB

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IDENTIFYING MACROMOLECULES IN FOOD LAB Introduction Carbohydrates, proteins, and fats are all essential nutrients. We cannot manufacture these nutrients, so we must ... – PowerPoint PPT presentation

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Title: IDENTIFYING MACROMOLECULES IN FOOD LAB


1
IDENTIFYING MACROMOLECULES IN FOODLAB
2
Introduction
  • Carbohydrates, proteins, and fats are all
    essential nutrients.
  • We cannot manufacture these nutrients, so we must
    obtain them from our environment.
  • The presence of these macromolecules can be
    detected by chemical indicators

3
Introduction
  • In 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.

4
Objective
  • Identify the presence of major nutrients in
    common foods
  • simple carbohydrates (glucose)
  • complex carbohydrates (starch)
  • Protein
  • Fat

5
What is an indicator?
  • Indicators are chemical compounds used to detect
    the presence of other compounds.

6
LAB SAFETY and CLEAN UP
Loose Hair BACK
WEAR safety goggles and apron at all times
THOROUGHLY CLEAN lab area and equipment with
plenty of water
NO GOOFING AROUND Automatic Failure of LAB
NO EDIBLE products in lab
WORK at LAB BENCHES ONLY
7
Test for Simple CarbohydratesBenedicts solution
  • Benedict's solution is a chemical indicator for
    simple sugars such as glucose C6H12O6.
  • ? yellow/green/brick red, etc. positive test

8
Test for Simple CarbohydratesBenedicts solution
  • Unlike some other indicators, Benedicts solution
    does not work at room temperature - it must be
    heated first.

9
ProcedureSimple carbohydrate
  • Add 5ml of food sample to test tube
  • Add 20 drops of Benedict solution
  • Place test tube in a hot water bath for
    10 minutes.

10
Test for Complex CarbohydratesIKI 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.

11
Test for Complex CarbohydratesIKI solution
  • IKI solution ? (Iodine Potassium Iodine) color
    change blue to black

12
ProcedureComplex carbohydrate
  • Add 5ml of food sample to test tube
  • Add 20 drops of IKI solution

13
Test for Protein (amino acids)Biuret solution
  • Biuret solution ? dark violet blue to pinkish
    purple is positive for protein

14
ProcedureProtein (amino acids)
  • Add 5ml of food sample to test tube
  • Add 20 drops of Biuret solution

15
Test for Fats (lipids)Sudan III
  • Like lipids, the chemical Sudan III is not
    soluble in water it is, however, soluble in
    lipids.
  • In this test dark red Sudan III is added to a
    solution.
  • If lipids are present the Sudan III will stain
    them reddish-orange (positive test).

16
ProcedureFats (lipids)
  • Add 5ml of food sample to test tube
  • Add 20 drops of Sudan III
  • Stopper and gently shake (rock) the test tube.
  • If the the Sudan III color mixes with the
    solution it is a positive test

17
Additional Fat Test
  • Fats will leave a glossy, oily residue when wiped
    on paper.

18
  • Procedure
  • Draw 6 squares on one side of your paper bag (5
    foods water)
  • With a fresh cotton swab, wipe a sample of the
    food to be tested in the square.
  • Let the paper dry.
  • Hold paper up to light and look for glossy, oily
    residue (use water as comparison).

19
Identification of Macromolecules in Foods
FOOD INDICATOR INDICATOR INDICATOR INDICATOR INDICATOR INDICATOR INDICATOR INDICATOR INDICATOR INDICATOR
FOOD Benedict (Sugar) Benedict (Sugar) IKI (Starch) IKI (Starch) Biuret (Protein) Biuret (Protein) Sudan III (Lipids) Sudan III (Lipids) Brown paper (Lipids) Brown paper (Lipids)
FOOD Color /- Color /- Color /- Color /- Color /-
Apple Juice
Potato
Egg White
Veg Oil
Milk
20
Macromolecule Test Protocols Table
INDICATOR MACRO-MOLECULE - TEST TEST PROTOCOL
Benedicts solution
IKI solution
Biuret solution
Sudan III
Brown paper
21
Procedure for Today
  1. Set up your notebook
  2. Go to your assigned station
  3. Write the PROCEDURE down in your notebook
  4. Make hypothesis which samples will test positive.
  5. Gather Samples
  6. Run Test Record Results
  7. Conclusion

22
Macromolecule Test Protocols Table
INDICATOR MACRO-MOLECULE - TEST TEST PROTOCOL
Benedicts solution simple carbohydrate blue Yellow, green, orange, Red 5 ml 20 drops 10 min. bath
IKI solution complex carbohydrate gold black 5 ml 20 drops
Biuret solution protein blue violet, black 5 ml 20 drops
Sudan III lipid Light pink reddish- orange 5 ml 20 drops rock
Brown paper Lipid No oily residue Oily residue Label wipe on paper, let dry
23
Exit Task
  • Why does the Sudan III not mix with the apple
    juice?
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