FOOD TESTS

Ethanol emulsion test:
- sample has to be crushed
- add alcohol to it to make a solution
- add water
- shake the tube
- if the cloudy emulsion forms then it shows presence of lipids

Starch test:

- add iodine solution to the sample 

- turns blue. black

   conclusion= starch is present 

- turns brown,

   conclusion= starch is absent 

Test for sucrose:
 sucrose is a non- reducing sugar which is made from glucose and fructose, which are reducing sugars

- performing Benedict test on a part of the sample to check for presence of reducing sugar
- if the colour stays blue, it means there are no reducing sugar present
- to check for presence of sucrose we proceed as following
1- take 2cm3 of sample
2- add 1 cm3 of HCL concentrated to it (this will on heating break down the glycosidic bonds between glucose and fructose which are reducing sugars
3- heat it and then cool it down
4- add Na2CO3 to neutralize HCL (conc)
5- add benedict solution and heat in H2O bath up to 90°C and observe the colour change

Reducing sugar test:

- add 2cm3 of sample 

- add 2cm3 of benedict reagent

- heat in a bath up to 90°C

 blue ---> red

 conclusion= reducing sugar is present 

 stays blue

 conclusion= reducing sugar is not present 

Protein test: [biuret test]

- take a sample in solution form (2cm3)

- add 2cm3 of biuret solution

- blue ---> purple

  indicates the presence of peptide bond

  conclusion= protein are present