Food tests Flashcards
How can we use a colourimeter to do a quantitive benedicts test
Measures the absorbance of light by coloured substance. Compare to data table.
Explain how a positive result is formed in Benedicts reagent
Reducing sugar reacts with the blue CU2+ to make brick red CU+
What is the test for a non reducing sugar
After testing for reducing sugars, add HCL and sodium hydrogencarbonate to to the solution then the Benedicts test
What is a positive result for benedict’s test?
Blue to Orange/brown
What is the test for reducing sugars?
Benedicts test. Equal volume of solution and reagent then heated.
What is a positive results for the iodine solution?
Blue black
What is the test for starch?
Iodine solution
What is benedicts reagent?
An aqueous solution of copper sulfate so when it reacts with a reducing sugar a precipitate of copper oxide is produced.
What is the test for lipids?
The emulsion test- add ethanol to the sample and shake. Then add water. If a white emulsion forms, lipid is present.
