How to Check if the Milk is Adulterated or Not: A Complete Guide

January 7, 2026 •

3 min read

According to the Food Safety and Standards Authority of India (FSSAI), a significant percentage of milk samples tested are non-conforming, with common adulterants including water, detergents, and urea. Knowing how to check if the milk is adulterated or not is therefore a vital skill for ensuring your family's health and safety. This guide details several easy-to-perform tests you can do in your own kitchen.

Quick Summary

This article provides simple, actionable steps to test milk purity at home, helping you detect common adulterants like water, starch, and detergents. It covers visual, boiling, and chemical tests using common household items. The content also highlights the health risks of consuming contaminated dairy products and emphasizes the importance of vigilance for consumer safety.

Key Points

Slanting Surface Test: Spot diluted milk by placing a drop on a tilted plate; pure milk leaves a trail, while watery milk runs quickly.
Iodine Test for Starch: Add a few drops of iodine to milk; a blue-black color indicates adulteration with starch.
Shake Test for Detergent: Vigorously shake milk with equal parts water; persistent, thick lather suggests detergent is present.
Soya-Litmus Test for Urea: Mix milk with soybean powder and dip a red litmus paper; a blue color change signals urea contamination.
Visual and Sensory Checks: Synthetic milk often feels soapy when rubbed between fingers and develops a yellowish tint when boiled.
Buy from Reputable Sources: To minimize risks, purchase milk from trusted dairy farms and certified vendors rather than unregulated sources.

Why Is Milk Adulteration a Serious Problem?

Milk is a staple in many diets, valued for its nutritional content. Adulterating milk compromises this nutritional value and introduces harmful substances. Common adulterants like water dilute nutrients, while chemicals can cause severe health issues. This practice is a significant public health risk, particularly in developing countries, often driven by economic motivations. Consuming adulterated milk can lead to a range of health problems, from digestive issues to long-term conditions like kidney damage.

The Health Hazards of Consuming Fake Milk

Chemicals used in adulteration can have serious health impacts. Formalin affects the liver and kidneys, urea can cause kidney and digestive problems, and detergents irritate the gastrointestinal system. Recognizing the signs of adulteration is crucial for consumer protection.

How to Detect Added Water in Milk

Water is frequently added to increase volume, reducing nutritional density and potentially introducing contaminants.

The Slanting Surface Test: Place a milk drop on a polished, slanting surface. Pure milk leaves a white trail, while water-diluted milk flows quickly with little to no trail.

How to Check for Starch in Milk

Starch is used to increase density, often to mask the addition of water.

The Iodine Test: Boil milk, let it cool, and add iodine tincture. A blue-black color indicates starch; pure milk remains unchanged.

The Simple Detergent Adulteration Test

Detergents create a frothy appearance, making milk seem richer.

The Lather Test: Shake milk with equal water in a bottle. Persistent, dense lather indicates detergent; pure milk forms minimal, fleeting foam.

How to Test for Urea in Milk

Urea artificially increases density and protein levels.

The Litmus Test with Soya: Mix milk with soybean or arhar powder and let it sit. Dip red litmus paper; it turns blue if urea is present. Pure milk doesn't change the paper's color.

A Visual Check for Synthetic Milk

Synthetic milk is a mix of harmful chemicals.

The Rubbing and Heating Test: Rub a drop between fingers; a soapy feel suggests synthetic milk. Heating synthetic milk often turns it yellowish.

Simple Milk Purity Tests: A Comparative Table


Adulterant	Test Method	Pure Milk Result	Adulterated Milk Result	Common Household Item Needed
Water	The Slanting Surface Test	Flows slowly, leaving a white trail	Flows quickly, leaving no trail	Polished plate or glass slide
Starch	The Iodine Test	Color remains unchanged	Turns blue-black	Iodine tincture
Detergent	The Lather Test	Forms minimal, quickly dissipating foam	Forms persistent, dense lather	Small bottle, water
Urea	Litmus Test with Soya	Red litmus paper stays red	Red litmus paper turns blue	Soybean/arhar powder, red litmus paper
Synthetic Milk	The Rubbing and Heating Test	Not soapy or sticky; remains white	Feels soapy; turns yellowish on heating	Fingers, heating source

Conclusion: Your Role in Ensuring Food Safety

Consumer awareness is vital alongside regulatory efforts to combat milk adulteration. Simple home tests offer a low-cost way to protect your family from contaminated milk. Choosing reliable sources and regular testing are key to ensuring the safety and authenticity of your milk.

Authoritative Link:

FSSAI DART Book: Detect Adulteration with Rapid Test

Frequently Asked Questions

To check for water, place a drop of milk on a polished, slanting surface. If it leaves a white trail as it flows, it is likely pure. If it flows quickly without leaving a trail, it has been diluted with water.

The simplest way is the lather test. Shake 5-10 ml of milk vigorously with an equal amount of water. If a dense, persistent lather forms, it indicates the presence of detergent. Pure milk will produce very little, quickly-disappearing foam.

Yes. While pure milk forms a thick cream layer on boiling, adulterated or synthetic milk often remains thin and watery, and may even turn yellowish.

For starch, perform the iodine test. Add 2-3 drops of iodine tincture to a small amount of milk. The appearance of a blue-black color confirms the presence of starch.

Yes, you can use the soybean powder and litmus paper test. Mix a small amount of milk with soybean or arhar powder. After a few minutes, if a red litmus paper dipped into it turns blue, the milk contains urea.

Consuming adulterated milk can cause severe health issues, including gastrointestinal complications, kidney damage, and liver problems due to harmful chemicals like formalin and urea. Water adulteration also reduces nutritional intake.

The Food Safety and Standards Authority of India (FSSAI) has published a guide called 'Detect Adulteration with Rapid Test' (DART), which provides detailed instructions for simple home tests.