Experiment 3 : Identification of food constituents in milk
To compare the composition of two different kinds of milk for fats, protein and reducing sugar.
In this experiment two milk samples are given and its compositions are tested using different methods such as using benedict solution to test the presence of reducing sugar, using copper II sulphate to test the presence of protein, using K3( to test the presence of fat. However in this experiment, not only are the milk tested for its composition, the amount of the particular substance such as reducing sugar, protein and fat is also tested by observing the intensity of the colour change.
Test tube, magnifying glass, test tube rack, dropper, cork, water bath.
Benedict solution, copper sulphate solution, K1, K2, potassium hydroxide, Sudan(IV)
A. The drop of milk in copper(II)sulphate solution
1. A clean test tube was filled with 1cm of the top with copper(II)sulphate solution. 2. Milk K1 was sucked into a clean teat pipette.
3. A drop of milk K1 was released into the copper(II)sulphate solution and the pipette was withdrawn slowly. 4. The movement of the drop of K1 was observed and noted. 5. The methods were repeated for solution K2.
6. Both observation was compared.
B. Test for lipids
1. Six test tubes are obtained and labeled from 1-6.
2. The materials listed in table 1 is added.
3. The contents in each test tube is mixed thoroughly.
4. The colour change of the tube contents are recorded.
C. Reducing sugar test
1. The water bath was brought to boiling point and the source of heat was turned down. 2. 2cm3 of each solution was added with 2cm3 of Benedict’s reagent. The reagent was mixed thoroughly. 3. The test tube was placed in the water bat and leaved for 5 minutes, shaking occasionally. 4. The result was recorded and noted.
D. Protein test
1. 2cm3 of each milk was...
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