Macromolecules

Standard Qualitative Tests

and

Testing Your Own Food

Qualitative

•Detecting if a substance is present

•You don’t know how much

SAFETY• IF A SOLID, cut into little pieces• Rinse razor blades under water,

do not wipe across the blade• Put used blades at the end of the

period in the “used beaker” on the cart

Goggles and Apron

• Chemicals are caustic to your eyes

• Iodine stains

When it asks for…

• Dropper Full• Just squeeze to fill dropper and release• Exact amounts are not important• 1 dropper full = 20-30 drops

Pasteur Pipets

NEVER EVER

• NEVER, hold a filled pipet upside down…or hold on its side…

You contaminate the bulb

For 5mL and 10 mL

• ACID• SUCROSE

Controls

• Positive Control• Absolutely expect

to see the result• Use the substance

(starch, glucose, etc.)

• Negative Control• Absolutely expect

to NOT see the result

• (may use water)

Lab Objective:

•Describe the test that indicates the presence of most small sugars.

Recording Benedict’s Results

• - blue no sugar• + blue/green trace• ++ green little sugar • +++ yellow some sugar• ++++ orange/red much sugar

Benedict’s Sugar Test

Lab Objectives:

• Describe the test that indicates the presence of starch.

• IODINE IS POISONOUS!!!

Iodine Test

negative

positive

Lab Objective:

• Define hydrolysis and give an example of the hydrolysis of carbohydrates.

• ANIMATION LINKS:Animation: Enzyme Action and the Hydrolysis of Sucrose

• Hydrolysing starch• WHFoods: How Does Digestion Work

and How Can I Improve Mine? (Animated graphics)

Hydrolysis“break with water”to make monomers

Lab Objective:

• Give examples of the formation/ breakdown of a:

• monosaccharide• disaccharide• polysaccharide

Lab Objective:

•Name the monosaccharide components of sucrose and starch.

Polysaccharide Disaccharide (sucrose)

Monosaccharide (glucose)

Two Common Monosaccharides

Simple Sugars

• Called monosaccharides• primary function = energy• Your SAMPLE will be

glucose

Disaccharide

•Double Sugar•Combined simple sugars•YOUR SAMPLE WILL

BE SUCROSE

Disaccharide

Now Let’s Demonstrate how Digestion Might Work

• Click Here Howstuffworks "The Digestive System"

Tube 1-blue (-) still sucrose, a disaccharide

Tube 2- heat broke bonds –so tested orange (+) for glucose

2 1

Tube 3

• Negative for because it is starch (a polysaccharide)

STARCH

Polysaccharides

• Shorter sugars link together to form complex sugars

• Your starch sample will be

POTATO STARCH

glucose

Tube 4

Starch Not heated – so it would be (+) for iodine, blue-black

Tube 5

• Heated 5 minutes – added Benedicts• Starch may just start to break down, so just a little (+)

for glucose or (-) starch did not break down yet

here

Tube 6• Heated 5

minutes added Iodine

• Brown – somewhat broken down – so just partially (+) for starch

Tube 6

Tube 7• Heated 15 minutes• Added Benedicts (for a glucose test)

Starch is broken down to its monomers, glucose

Tube 7

Tube 8

• Heated 15 minutes – Tested for starch

• Negative, because it is broken down to glucose TUBE 8

Explain Benedict’s test on sucrose

• AT first sucrose is (-) with Benedicts because it is a disaccharide.

• After hydrolysis (heating and acid), the monosaccharide glucose is (+)

Explain the iodine test with starch

• At first starch is (+) with iodine.

• After hydrolysis, the starch breaks down to glucose and tests (-) with iodine.

Explain Benedicts with starch.

• At first starch would be (-) for it is not glucose, but is a polysaccharide.

• After hydrolysis, glucose is formed when the bonds break.

Why does hydrolysis of starch take longer than of sucrose?

• Starch is a polysaccharide, more bonds to break.

• Sucrose is a disaccharide.

Cellulose

Dehydration Synthesistake out water to make

macromolecule

Complex Carbohydrates

• Starch -storage in plants• Cellulose -fiber• Glycogen-storage in animals

Testing for Fats and Proteins

• Read Lipids Intro p. 9 and answer the questions to the left (3)

• Read Proteins Intro p. 10 and answer the questions to the right (3)

• Mrs. Sheldon will demonstrate the Separation of Butter lab.

Fat Test with Brown PaperTranslucent (light can go through)

= + fat test

Protein Test with Biuret’s

Describe the Protein Test

• Biuret’s is what color?• Blue• In the presence of a protein it will

turn what color?• purple

Biurets turns purple in the presence of protein

Neg. Lots Slight

Separation of Butter

• Clarification is removing lipid part (water insoluble) from non-lipid part (water-soluble).

• Why do it? Clarifying butter raises the smoke point from 250oF to 350oF.

Emulsion

Oil droplets (micelles) are formed in water-soluble substances

Oil is non-water-soluble

Heat breaks up the Emulsion-separates the butter

Ghee A common food fat in India, ghee is

produced from boiled buffalo milk. Its manufacture is similar to that of butter oil. It can be kept for months, or years, without refrigeration, and has a more intense flavor

than butter or butter oil.

Clarified Butter (Ghee)separated into:

Protein foam on top skimmed off

Next layer = clarified butter

Bottom layer = milk solids - flavor

BRING IN FOODS TO TEST

• We can grind, chop, dilute them to make them dissolve in water

• We will run all the tests on them

While you Wait…

• Do exercises from the handouts:–Lipid Crossword–Exercise 6–Exercise 7–If you have trouble, use text CD