Food tests Flashcards
What is the test for starch
iodine test
orange to blue/black
What is a reducing sugar
all monosaccharides and many disaccharide molecules (maltose)
How do you test for reducing sugars
add benedicts solution to sample and heat at 80* in a water bath for 5 minutes
What is the positive test for reducing sugars
blue to orange/red precipitate
How do you test for non-reducing sugars (sucrose)
add hydrochloric acid to the sample and boil in a water bath
(hydrolyses any sucrose present)
neutralise the solution with sodium carbonate
add benedicts solution
What is the positive test for non-reducing sugars
blue to orange/red
(on the second test)
How do you test for protein
add biurets reagent to the sample
What is the positive test for protein
blue to lilac
How do you test for lipids
add ethanol to the sample
pour the test tube into another containing water
What is the positive test for lipids
a white emulsion forms
