Food Tests

Testing for Simple Sugars (Benedicts Solution)

Aim: I want to find out how to test for simple sugars 

Equipment:

• Bunsen burner 
• Safety glasses
• Test tube tongs 
• Test tube
• Benedicts Solution 
• Food sample 

Method: 

1. Place about 2mL of the food sample into a test tube and then add 5 drops of Benedicts solution 
2. Heat the test tube over a blue flame (DO NOT LET BOIL)

Results 

A positive test for a simple sugar result in the Benedicts Solution changing from a blue colour to a yellow colour to an orange/red colour. 

Conclusion

Orange Juice reacted with Benedict's Solution. Therefore orange juice must contain simple sugar. 

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Testing for Complex Sugars (Iodine Test)

Aim:

I want to find out how to test for complex sugars.

Equipment: 

• Iodine solution 
• Food sample 

Method: 

1.  Place 2mL of the food sample into a test tube.
2. Add 3-5 drops of iodine.

Results: 

If complex sugars are present, the iodine solution will change from a brown colour to a black colour.

Conclusion: 

Bread reacted with iodine solution. Therefore bread contains complex sugars.

Testing for Protein (Biuret Test)

Aim:
I want to find out how to test for protein.

Equipment:

• Test tube
• Food sample 
• Sodium Hydroxide 
• Copper Sulfate 

Method: 

1. Put the food sample into the test tube
2. Add 5 drops of Sodium Hydroxide to the food sample
3. Add 5 drops of Copper Sulfate to the test tube
4. Gently shake from side to side

Results: 

If the solution remains blue, then no protein is present. If the solution turns to a purple colour, then protein is present in the sample. 

Conclusion: The solution turned purple therefor egg does contain protein. 


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