Topic 1 - Core Practical : Investigating Macronutrients Flashcards
What is the reagent used to test for starch?
Iodine solution
The iodine solution changes color to indicate the presence of starch.
What color change indicates the presence of starch when using iodine solution?
Orange to blue-black
A positive result for starch is indicated by this color change.
What reagent is used to test for reducing sugars?
Benedict’s Solution
Benedict’s solution is blue before the test and changes color if reducing sugars are present.
What color change indicates the presence of reducing sugars when using Benedict’s Solution?
Blue to reddish-brown
This color change occurs after boiling the mixture.
What method is used to test for protein?
Biuret Test
This test involves potassium hydroxide and copper sulfate.
What color change indicates the presence of protein in the Biuret test?
Blue to violet
A violet color indicates the presence of proteins.
What test is used to identify lipids?
Emulsion Test
This test involves ethanol and deionized water.
What indicates the presence of lipids in the Emulsion Test?
Formation of a white emulsion layer
The emulsion layer forms at the top of the sample.
How can we improve food tests?
Use a control in each experiment
Positive and negative controls help to confirm results.
What is a positive control for the Biuret test?
Anything containing protein (e.g. egg white)
This control confirms that the test can detect protein.
What is a negative control for the Biuret test?
Distilled water
This control shows what a negative result looks like.
Fill in the blank: The method for testing reducing sugars involves adding _______ to a food sample.
Benedict’s Solution
True or False: The Emulsion Test for lipids requires boiling the sample.
False
The Emulsion Test does not require boiling.
