Food tests Flashcards
What is the test for sugars(reducing)
benedicts test
What is the test for starch
Iodine solution
what is the test for proteins
biuret test
What is the test for lipids
Sudan III
The steps you have to do for every food (apart from lipids) to get the food sample
First get your piece of food and break it up with a motar and pestle
then put the crushed food into a beaker with distilled water and stir with a glass rod until some dissolves ,
then filter out the solution with a funnel and filter paper to get rid of the solid bits of food in the solution
describe the benedicts test for sugars
5cm cubed of food sample in test tube , add 10 drops of benedicts solution to the test tube.Get a water bath at 75 degrees and put the test tube in the water bath in a test tube holder and the benedicts solution is BLUE and if there are reducing sugars present the solution will turn to Green Yellow Or Red depending on the concentration of sugar , high concentrations will have red
describe the iodine test for starch
5cm cubed of food sample in test tube and add few drops of iodine solution and if the starch is present it will go from orange yellow to blue black
Describe the biurets test for proteins
2cm cubed food sample in test tube and add 2cm cubed of the solution which turns it BLUE but then if proteins are present it will change to pink or purple
Describe the sudan III test for lipids
5cm cubed food sample (not filtered) with 3 drops of sudan III solution and gently shake , if lipids present then the lipids should get stained with a red layer at top
or alternative ethanol test with distilled water and goes cloudy for fats
how much ml of food sample for each test and extra details
5 cm3 for each except from biurets - 2cm3
also for the lipids test don’t filter out food pieces
Iodine - orange yellow to black
Biurets - blue to purple violet
benedicts - Blue to green/yellow/red
Sudan III - lipid stained red layer on top
