Title: Food Tests
Aim: To determine the nutrient content of various food samples
Materials/Apparatus
● Jam
● Banana
● Avocado
● Peanuts
● Chicken
● Test tubes
● Mango
● cheese
● Test tube rack
● Rice
● Bread
● Vegetable oil
● Fish
● Distilled water
● Droppers
● Beakers
● Bunsen burner
● Iodine solution
● Benedict’s solution
● Mortar and pestle
● Dilute hydrochloric acid
● Dilute sodium hydroxide
● Measuring cylinder
● Biuret solution
● Ethanol
● Labels
Method:
1. Using the mortar and pestle, crush each solid food sample separately. Wash the mortar
and pestle after crushing each fruit.
2. Place the crushed foods and jam into separate beakers and mix with a small amount of
distilled water. Label the beakers.
Starch Test
3. Label 11 test tubes for each food.
4. Add 2 cm3 of each food sample into its respective test tube.
5. Add 2-3 drops of iodine to each test tube and shake gently.
6. Record any colour change.
Protein Test
7. Repeat steps 3 and 4.
8. Add 2cm3 of biuret solution to each test tube and shake gently.
9. Record any colour change over a 5 minute period.
Test for Reducing Sugars
10.Repeat step 7.
11.Add 2cm3 of benedict’s solution to each test tube and shake gently.
12.Place the test tubes in a hot water bath for 5 minutes.
13.Record any colour change.
Test for Non-Reducing Sugars
14.Repeat step 10.
15.Add 1cm3 of dilute hydrochloric acid to each test tube.
16.Place the test tubes in a boiling water bath for 1 minute.
17.Add 1cm3 of dilute sodium hydroxide to each test tube.
18.Add 2cm3 of benedict’s solution to each test tube then shake and boil gently.
19.Record any colour changes.
Emulsion Test for Fats
20.Repeat step 14.
21.Add 2cm3 of ethanol to each test tube and shake vigorously.
22.For each sample, decant the ethanol into a separate test tube containing 2ml of distilled
water.
23.Record observations.
Diagram:
Results:
Starch Test Protein Test Test for Test for Emulsion Test
Reducing Non-Reducing for Fats
Sugars Sugars
Food Colou Infere Colou Infere Colou Infere Colou Infere Colou Infere
Sampl r nce r nce r nce r nce r nce
e chang chang chang chang chang
e e e e e
Jam Bro Star Blue Prot Oran Red Redi Non- Clea Fats
wn ch ein ge ucin sh-b Red r Abs
Abs Abs g row ucin ent
ent ent Sug n g
ars Sug
Pres ars
ent Pres
ent
Ban Blue Star Purp Prot Red Red Redi Non- Clea Fats
ana -Bla ch le ein ucin sh-b Red r Abs
ck Pres Pres g row ucin ent
ent ent Sug n g
ars Sug
Pres ars
ent Pres
ent
Avo Bro Star Purp Prot Blue Red Blue Non- Clou Fats
cad wn ch le ein ucin Red dy Pres
o Abs Pres g ucin ent
ent ent Sug g
ars Sug
Abs ars
ent Abs
ent
Pea Bro Star Purp Prot Blue Red Blue Non- Clou Fats
nuts wn ch le ein ucin Red dy Pres
Abs Pres g ucin ent
ent ent Sug g
ars Sug
Abs ars
ent Abs
ent
Chic Bro Star Purp Prot Blue Red Blue Non- Clea Fats
ken wn ch le ein ucin Red r Abs
Abs Pres g ucin ent
ent ent Sug g
ars Sug
Abs ars
ent Abs
ent
Man Bro Star Blue Prot Red Red Redi Non- Clea Fats
go wn ch ein ucin sh-b Red r Abs
Abs Abs g row ucin ent
ent ent Sug n g
ars Sug
Pres ars
ent Pres
ent
Che Bro Star Purp Prot Blue Red Blue Non- Clou Fats
ese wn ch le ein ucin Red dy Pres
Abs Pres g ucin ent
ent ent Sug g
ars Sug
Abs ars
ent Abs
ent
Rice Blue Star Blue Prot Blue Red Blue Non- Clea Fats
-Bla ch ein ucin Red r Abs
ck Pres Abs g ucin ent
ent ent Sug g
ars Sug
Abs ars
ent Abs
ent
Brea Blue Star Purp Prot Oran Red Redi Non- Slig Fats
d -Bla ch le ein ge-R ucin sh-b Red htly Low
ck Pres Pres ed g row ucin Clou
ent ent Sug n g dy
ars Sug
Pres ars
Pres
ent ent
Veg Bro Star Blue Prot Blue Red Blue Non- Clou Fats
etab wn ch ein ucin Red dy Pres
le oil Abs Abs g ucin ent
ent ent Sug g
ars Sug
Abs ars
ent Abs
ent
Fish Bro Star Purp Prot Blue Red Blue Non- Clea Fats
wn ch le ein ucin Red r Abs
Abs Pres g ucin ent/
ent ent Sug g Low
ars Sug
Abs ars
ent Abs
ent
Discussion:
1. Discuss nutrition and balanced diet.
2. Why is distilled water used to prepare the samples?
3. Explain the chemical reactions for each test (starch, protein, reducing sugars,
non-reducing sugars, emulsion).
