SOP: Detection of Starch in Milk (Qualitative Method)

GIFSQ — Global Institute for Food Safety & Quality

1. Principle

Starch molecules form a blue colored complex with iodine. Incorporation of starch in milk can be detected by adding iodine solution to it.

2. Reagents

a. Iodine solution: dissolve 2.6 g of iodine and 3 g of potassium iodide in a sufficient quantity of water and make up to 200 mL.

3. Procedure

Take about 5 mL of milk in a test tube

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Bring to boiling condition and allow the test tube to cool to room temperature

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Add 1–2 drops of iodine solution to the test tube

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Observe the color

Interpretation: Development of blue color indicates the presence of starch. The blue color disappears when the sample is boiled and reappears on cooling.

Limit of detection: 0.02%

References

Manual of Methods of Analysis of Foods, Milk and Milk Products, FSSAI 2016, 1.2.2.1.