Preparation of Milk Sample for Analysis

Testing Methodology

Preparation of milk sample for analysis

Warm the sample to 37- 40°C by transferring it to the beaker and keeping it in a water bath maintained at 40 - 45°C. Stir slowly for proper mixing homogenization. Mix sample thoroughly by pouring back into the bottle, mixing to dislodge any residual fat sticking to the sides and pour it back in the beaker. During mixing do not shake the bottle vigorously. Allow the sample to come to room temperature (26- 28°C) and withdraw immediately for analysis. If small clots or lumps are observed in the sample which cannot be dispersed, a few drops of liquor ammonia may be used during homogenization. If even after homogenization the sample shows lumps or clots or droplets of oil are visible suggestive of curdling /splitting of milk, the sample should be deemed unfit for analysis and rejected.

Reference

FSSAI Manual of methods of analysis – milk and milk product (2016) – page no. 9

5. Test for Presence of Hydrogen Peroxide in Milk

5.1 Using Potassium Iodide and Starch method

5.1.1. Reagents

A. Potassium iodide solution: Weigh 20 g of potassium iodide and dissolve it in distilled water to obtain a 100 ml solution.

B. Starch solution: Take 1 g starch powder and dissolve it in distilled water by heating and make up the volume to 100 ml.

C. Potassium iodide–starch reagent: Mix equal volumes of 20% potassium iodide solution and 1% starch solution.

5.1.2. Procedure

Take 1 ml of milk sample in a test tube. Add 1 ml of the potassium iodide-starch reagent and mix well. Observe the color of the solution in the tube. Blue color will be developed in the presence of H2O2, whereas pure milk sample remain white in color.

Reference

Sharma, R.; Rajput, Y.S. and Naik, N.L. (2012).Detection of adulterants in milk – a laboratory manual. NDRI Publication No. 88/2012, NDRI, Karnal, page 10.