Te Kura Māori O Porirua
Learning Objectives:


To understand the main components of the
human diet.
To test for the presence of starch, glucose
protein and fat in a food sample.
Starter:

List the 7 parts of the human diet.
Seven Parts of the Human Diet
Carbohydrates
Water
Minerals
Fibre
Protein
Vitamins
Fats
Practical Activity

Safety First:

Wear safety goggles

Stand up
Tuck your chair &
bags under your desk


Tie back long hair
8A What’s in food?
We can test foods to find out what chemicals they
contain.
Orangey-brown iodine turns blue-black when it
reacts with starch.
drop iodine solution onto
the food
black = starch
8A What’s in food?
Blue Benedict’s solution turns orangey-red when it
is boiled with glucose.
chopped
up food
hot water
heat
blue turns orange/red
= glucose
8A What’s in food?
In the Biuret test the solution turns purple.
potassium
hydroxide
shake
copper
sulphate
purple = protein
chopped up
food
8A What’s in food?
Fats go cloudy white when they are mixed with
ethanol and water.
filter
add
water
grind food
with ethanol
cloudy = fat
Now see if you can use these tests to identify the
food chemicals on the next slides.
8A What’s in food?
For each food, decide on the chemicals found in them.
Food sample
Protein
Test
Result
Iodine solution
orangey-brown
Benedict’s test
blue
Biuret test
purple
Ethanol test
cloudy white
Fats
Starch
Glucose
8A What’s in food?
For each food, decide on the chemicals found in them.
Food sample
Protein
Test
Result
Iodine solution
blue-black
Benedict’s test
blue
Biuret test
blue
Ethanol test
clear
Fats
Starch
Glucose
8A What’s in food?
For each food, decide on the chemicals found in them.
Food sample
Protein
Test
Result
Iodine solution
orangey-brown
Benedict’s test
orangey-red
Biuret test
blue
Ethanol test
clear
Fats
Starch
Glucose
8A What’s in food?
For each food, decide on the chemicals found in them.
Food sample
Protein
Test
Result
Iodine solution
orangey-brown
Benedict’s test
orangey-red
Biuret test
blue
Ethanol test
clear
Fats
Starch
Glucose
Experiment!


You’ve been given a sample of foods. Test
these foods using the four food tests to see
what energy chemicals they contain!
Complete this table with your results.
Food
Starch
Glucose
Protein
Fat
Cream
Cake
?
?
?
?
8A A food test for YOU!
1. A balanced diet…
a) contains the same amounts of the main food groups
b) contains healthy amounts of the main food groups
c) doesn’t fall off the table.
2. A balanced diet for most people has more…
a) fat than water
b) carbohydrate than protein
c) crisps than fruit.
8A A food test for YOU!
3. To test for protein in food you…
a) add iodine solution
b) do the Biuret test
c) poke it with a big stick.
4. Sugar and starch are both…
a) proteins
b) fats
c) carbohydrates.
8A A food test for YOU!
5. Iodine solutions turns blue-black with…
a) starch
b) protein
c) age.
6. A food went orangey-red when it was boiled with
Benedicts solution. It could be…
a) a carrot
b) a boiled sweet
c) a sausage.
Food Tests
Learning Objectives:


To understand the main components of the
human diet.
To test for the presence of starch, glucose
protein and fat in a food sample.