Food tests

Question 1

how do you prepare a food sample

Answer 1

1 - break it up using a pestle and mortar
2 - put it in beaker and add distilled water
3 - stir with a glass rod until some of food has dissolved
4 - filter to get rid of solid food

Question 2

which test is used to test for sugars and how does it work

Answer 2

benedict’s test
1 - prepare food and transfer into a 5cm^3 test tube
2 - set water bath to 75 C
3 - add benedict’s solution to test tube
4 - put test tube into bath and wait 5 minutes
5 - it will change from blue to green , yellow or red if the sample contains reducing sugar

Question 3

which test is used to test for starch and how does it work

Answer 3

iodine solution test
1 - food sample into 5cm^3 test tube
2 - add iodine solution and gently shake
3 - if containing starch will change from browny-orange to black or blue-black

Question 4

which test is used to test for proteins and how does it work

Answer 4

Biuret test
1 - prepare sample and put in 2cm^3 test tube
2 - add 2cm^3 of biuret solution and shake gently
3 - if containing protein will change from blue to pink or purple

Question 5

which test is used to test for lipids and how does it work

Answer 5

sudan III test
1 - prepare sample and put into 5cm^3 test tube
2 - use pipette to add drops of sudan III solution and shake gently
3 - if containing lipids will separate into two layers - top layer being red