FOOD CHEMISTRY
Applied to a biology class in the macromolecules
section.
PURPOSE


To illustrate the chemical testing procedures for
fats, sugars, starches, and protein.
Core 40 application is extensive, many of the
questions are based on proteins, lipids, and
carbohydrates.
PRE-LAB

Prior to this lab a model building lab would have
taken place.
In that lab they construct a glucose and a lipid
monomer, then they add it to their neighbors to
create the polymer. In this process they also discover
dehydration synthesis.
 Also a protein synthesis lab, where they pick an
amino acid to construct and then add it to their
neighbors to create the protein.

PRIOR KNOWLEDGE GAINED
The students will know what a monomer, and
monosaccharide are, and what they do. As well as
how they contribute to the polymers, and what
polymers actually are.
 They will understand the ratios within the lipids.
 As well as the effects of saturated, unsautared,
and polyunsaturated.

WHAT THEY SHOULD LEARN
What foods contain the four macromolecules.
 How they effects us.
 What the different types are in various forms.



Ex. Maltose, lactose, glycerin.
Finally what the chemical reaction are and how
they tell use what a sugar, protein, lipids, and
carbohydrate actually are.
SET-UP
CAN BE ACCOMPLISHED

IN MULTIPLE WAYS.
Basic
• Four groups of four test tubes.
• First group is Sugar
• Second is starch
• Third is protein
• Fourth is oil

Each of the four test tubes in the group will be
for the reaction of the Benedict's, potassium
iodide, Sudan IV, and Buiret reagent.
VARIATIONS ON THE SET-UP

Have the students set-up the groups


That also gives away the mystery.
Have the teacher set it up as I have done.

Number each group.
1-sugar
 2-starch
 3-protein
 4-lipid


Letter each tube within the group, A-D
A-Benedict’s
 B- Potassium-iodide
 C-Sudan IV
 D- Buiret Reagent

VARIATIONS ON THE SET-UP

Each group of students
Tests all the macromolecules, Sugar, Carbohydrates,
Lipid, and Starch
 Test one of the above.
 Test all of the above and an unknown
 Test one of the above, then present it to the class.
The next day give each group one or two unknowns to
figure out what food they are.


Can include computer lab access to elaborate on their
presentation, or to let them search for what their unknown
is, if given a more difficult example like peanut butter, or
lettace.
EXPERIMENT
WHAT WE WILL BE DOING TODAY
Two groups will use the given chemicals that
came with the lab. The third group will be using
real food samples.
 Everyone add 5ml of distilled water to all the
tubes.



Distilled water is in the smaller faucet, on the left
side.
Group one and two place 2-3 drops of each
macromolecule to the corresponding test tube.
1-sugar - dextrose
 2-starch - starch soln.
 3-protein - gelatin
 4-lipid - veg. oil

EXPERIMENT

Group three will be using,




1-syrup
2-instant mashed potatoes
3-egg whites
4-veg. oil
Again telling the students this is an option.
 Everyone picks up on procedure 4 in the
experiment lab provided.

EXPERIMENT
PLEASE RECORD YOUR OBSERVATIONS SO WE CAN SEE IF THE
EXPERIMENT ACTUALLY WORKED.

Benedict’s solution goes into all of the ‘A’ test
tubes.
Add 10 drops and place in the hot water bath for 10
minutes.
 If sugar is present a color change will occur form
yellow to orange.


Potassium iodide solution to all of the ‘B’ test
tubes.
Add one drop.
 Starch turns blue in the presence of iodine, and
animal starch turns mahogany red in the presence of
iodine.

EXPERIMENT
PLEASE RECORD YOUR OBSERVATIONS SO WE CAN SEE IF THE
EXPERIMENT ACTUALLY WORKED.

Sudan IV to all of the ‘C’ test tubes.
Add one drop.
 Can act as a color tag.



Has been known to not work well.
Buiret reagent to all of the ‘D’ test tubes.
Add 10 drops and allow 10 minutes for the color
change to take hold.
 The color change will be from blue to violet to pink.
 It may fade, because it is a reversible reaction.


Please pay attention to this reaction because it has been
known that more drops may need to be used.
IDEAS FOR THE CLASS ROOM
Each group gets to test all of them, like we did
today.
 Each group gets one.
 Each groups gets one, and has to present it.
 Each group gets to test all of them, but with real
food samples. (individual groups get different
types of samples)
 Each group gets one food sample.
 Each groups one food sample and has to present
it.

IDEAS FOR THE CLASS ROOM

Add on to each group gets one sample and has to
present it.


The next day they receive some unknowns and have
to test it like the day before. Once complete they
describe their results, and tell what the actual food
item is.
Other ideas??
Less diluition for a brighter color change when doing
the chemical section of the lab
 Egg whites turn purple in Benedicts soln
 Make sure the potassium iodine works
 Make sure the benedicts is qualitative, for the orange
reaction.
