food tests Flashcards
name for protein test
biurets
colour change for protein
blue to violet/purple/lilac
name for lipids test
ethanol
colour change for lipids test
colourless to milky/cloudy
name for starch test
iodine
name for glucose test
benedicts
colour change for glucose
blue to brick red
colour change for starch
orange to blue black
benedicts test carried out
add benedict’s solution to sample solution in a test tube
heat in a boiling water bath for 5 mins
take out and observe colour
if there is glucose colour will have changed from blue to orange/brick red
iodine test carried out
add drops of iodine to food sample
if colour changes from orange to blue black then starch is present
buriets test carried out
add drops of biuret solution to food sample
colour change will be from blue to violet/purple if protein is present
ethanol test carried out
mix food sample with 4cm³ of ethanol and shake
allow time for food sample to dissolve in ethanol
strain ethanol solution into another test tube
add ethanol solution to 4cm³ of cold distilled water
positive test will show milky, cloudy emulsion forming
