OBJECTIVE: To detect the presence and amount of protein in a food sample. INTRODUCTION:
A protein is complex, high molecular-mass, organic compound that consist of amino acids joined by peptide bonds. Proteins are essential to the structure and function of all living cells and viruses. Millon test is given by any compound containing a phenolic hydroxyl group. Consequently, any protein containing tyrosine will give a positive test of a pink to dark-red color. The millon reagent is a solution of mercuric and mercurous ions in nitric and nitrous ions in nitric and nitrous acids. Caution, millon reagent is highly toxic and corrosive. The red colour is probably due to mercury salt of nitrated tyrosine. The ninhydrin reaction is used to detect the presence of α-amino acids and proteins containing free amino groups. When heated with ninhydrin, these molecules give characteristic deep blue colors. This reaction involved in this test are shown below
EXPERIMENT 1 : PROTEIN DETECTION TEST MILLON TEST
OBJECTIVE: To detect presence of protein containing amino acid tyrosine
1. Millon reagent
1. 1ml of casein, tyrosine, albumin and glycine was placed into separate labeled test tube. 2. 3 drops of millon reagent was added to the test tube.
3. The test tube was immersed in the water bath for 5 minutes. 4. The test tube was let cooled and the colour formed was observed and recorded.
| Clear solution
| Clear solution
| Brick red precipitate form
| Dark purple
EXPERIMENT 2 : PROTEIN DETECTION TEST NINHYDRIN TEST
OBJECTIVE: To detect the presence of α-amino acids and proteins containing free amino acid
MATERIALS: 1. Casein
1. 4 drops of ninhydrin was...
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