Food Tests Flashcards
How do you test for starch?
By using iodine solution- add a few drops of iodine onto small food samples.
What is the colour change when starch is present in iodine solution?
From yellow-orange to blue-black.
How do you test for reducing sugars?
Using Benedict’s solution- equal volumes of food solution and Benedict’s solution are mixed and placed in a hot water bath.
What is the colour change when reducing sugars are present in Benedict’s test?
From blue to pink-red.
How do you test for protein?
Using the biuret test- potassium hydroxide is mixed with a solution of the food. Two drops of copper sulfate solution are added.
What is the colour change when the biuret test is used when protein is present?
From pale blue to purple.
How do you test for fats and oils (lipids)?
Ethanol emulsion test- food is mixed with ethanol and shaken. Some of the mixture is poured into water and shaken again.
How do you know that lipids are present in the ethanol emulsion test?
Fats and oils float to the surface of the water forming a cloudy emulsion.
