Milk Adulteration: Tests a Collection Centre Can Run

For milk adulteration, a collection centre can check water with a lactometer or an analyser. It can test urea, starch, salt, detergent and neutraliser with a few reagents or a strip kit, for about ₹12 a test. The analyser on your counter does not do those five for you, so a good fat reading does not mean clean milk.

How common is milk adulteration?

FSSAI tested 6,432 samples in its 2018 national survey. Only 12 were adulterated in a way that made them unsafe: 6 with hydrogen peroxide, 3 with detergent, 2 with urea and 1 with neutraliser. About 41% were safe but fell short on a quality measure. FSSAI names low fat and low SNF, and gives dilution with water as one reason. Maltodextrin turned up in 156 samples and sugar in 78, mainly in processed milk. FSSAI says these are sometimes added to raise fat and SNF.

That survey covered milk across towns, not your supplier cans, so read it as a pattern and not a rate. The pattern is useful. Water is the daily problem. Things added to hide the water come next. Dangerous chemicals are rare, but one failed load can cost you more than a year of testing.

Milk adulteration test at home: what FSSAI's DART book shows

FSSAI's DART book (Detect Adulteration with Rapid Test) is the milk adulteration test FSSAI gives to households. Its milk section has four tests: water, detergent, starch in milk and its products, and starch in ghee or butter. You need a glass, water and tincture of iodine.

Test	What to do	Clean milk	Adulterated milk
Water	Put a drop of milk on a polished slanting surface	Stays, or flows slowly and leaves a white trail	Flows at once and leaves no mark
Detergent	Shake 5 to 10 ml of milk with an equal amount of water	A very thin layer of foam	Dense lather
Starch in milk	Add 2 to 3 drops of tincture of iodine	No blue	Blue colour
Starch in khoa, chhena or paneer	Boil 2 to 3 ml of sample with 5 ml water, cool, add 2 to 3 drops of tincture of iodine	No blue	Blue colour
Starch in ghee or butter	Half a teaspoon in a glass bowl, add 2 to 3 drops of tincture of iodine	No blue	Blue colour

The book says its aim is to make consumers aware, and that it is written for the household. So treat a DART result at the counter as a reason to run a proper test, not as proof against a supplier. It has no test for urea, salt or neutraliser. For those three, use the FSSAI manual methods in the next table or a strip kit.

Which test for which adulterant?

The methods below come from FSSAI's milk manual and FSSAI's DART tests. DART is written for homes. Its milk page covers water, detergent and starch and leaves out urea, salt and neutraliser, so a centre needs the manual or a kit for those three.

Adulterant	Why it is added	Test	What you see	Can it detect
Water	More litres	Lactometer or analyser. DART: drop of milk on a polished slope	Reading falls. Watered milk runs off with no white trail	Rough check only
Urea	An ingredient of synthetic milk	1 ml milk plus 1 ml of 1.6% DMAB reagent	Distinct yellow. Normal milk stays slightly yellow	0.2% added urea
Starch	Raises SNF	Boil 5 ml, cool, add 1 to 2 drops iodine solution	Blue, gone on boiling, back on cooling	0.02%
Salt	Raises the lactometer reading	5 ml milk, 1 ml 0.1 N silver nitrate, 0.5 ml 10% potassium chromate	Yellow means salt added. Chocolate brown means none	0.02%
Detergent	Emulsifies oil, or poor can washing	DART: 5 to 10 ml milk, equal water, shake hard	Dense lather. Pure milk gives a very thin foam	Rough check only
Neutraliser	Hides souring	2 ml milk plus 2 ml of 0.05% rosalic acid	Rose red. Pure milk stays brownish	0.1% caustic soda or soda ash, 0.2% baking soda

Some notes from the counter side.

Urea. All milk has some. FSSAI gives 20 to 70 mg per 100 ml as natural, and above 70 mg as added. Run a known clean sample beside the suspect one, because the colour difference is what you are reading.

Salt. FSSAI's manual says chocolate brown for clean milk, and the NDRI manual calls it brick red. Same result, different word. Again, compare with clean milk.

Detergent. The lather test is the only one a counter can do. The lab method needs chloroform and a centrifuge, and it does not belong near food. Not all foam means adulteration either, since the manual also names poor rinsing of equipment as a cause. Check your own cans first.

Neutraliser. The manual says it is added to cover acidity that has developed in the milk. So this is the test for hot months and for milk that came a long way.

Hydrogen peroxide. Not one of the six above, but it was the most common adulterant in the FSSAI survey. Buy a kit that covers it.

Reagent work means acid, alcohol and silver nitrate on the premises. Label them, lock them away from milk, and do not pipette by mouth.

What can a lactometer catch, and what can it not?

A lactometer shows density, and only that. The CLR you read from it goes into the SNF sum.

Here is what water does to a sample. Say milk reads FAT 4.0 and CLR 28. With SNF = CLR/4 + 0.21 × FAT + 0.36, SNF is 8.20. Add 10% water and FAT falls to about 3.6, CLR to about 25.2, and SNF to about 7.42. On plain milk, the lactometer catches this.

Now the trick. The NDRI manual lists cane sugar, common salt and sulfate salts as things added to raise the lactometer reading or the SNF. Maltodextrin too. Put a little in the watered milk and the CLR climbs back. The lactometer is happy, and you are paying for water.

Problem	Lactometer	Ultrasonic analyser	What settles it
Plain water	Reading falls	Added water figure, ±5%	Compare with supplier's past readings
Cream taken off	Reading rises, because fat is lighter	FAT falls	FAT test
Water plus salt or sugar	Looks normal	SNF can look normal	Silver nitrate test, sugar test
Urea	No signal	Not reported	DMAB or strip
Starch	No signal you can trust	Not reported	Iodine
Detergent	No signal	Not reported	Shake test, lab
Neutraliser	No signal	Not reported	Rosalic acid or strip

A low reading is not proof of water either. FSSAI says fat and SNF in raw milk vary by species, breed and feed. A thin reading from a poorly fed animal points to the khurak. Look at the supplier's own history before you say a word to him.

Take readings the same way each time. NDRI's method warms the sample to 40 to 45°C, cools it to 27 ± 2°C, and then corrects the reading to 27°C from a table. At the counter you will not do all that, but keep one temperature and do not float the lactometer in foam.

What can an analyser catch, and what can it not?

An ultrasonic analyser gives fat, SNF, added water and a few more figures. The NDDB specification asks for added water within ±5%.

Read that number with care. The Lactoscan manual says the machine "does not measure the freezing point, but calculates it" from the other readings, and the added water figure rests on a basic freezing point set for your region. Set it badly and honest milk shows water. With a ±5% tolerance, a reading of 3% does not prove anything. Ask your dealer to set it, and use it to spot a change in one supplier, not to charge him.

Neither the NDDB specification nor that manual lists urea, starch, detergent or neutraliser as a reading. The next step up is an FTIR screen. FOSS MilkoScreen flags most of this list and gives limits such as 0.10% urea and 20% added water, in 45 seconds with no chemicals. One listing shows ₹4,90,000 (checked November 2026). That is for a plant reception dock. At a village centre it is not worth buying. A ₹25,000 analyser plus a kit does the job at this scale.

Milk adulteration test kit price, and what each kit covers

All prices are seller or press figures, checked November 2026. Treat them as a starting point and ask for a current quote.

Item	Covers	Listed price	Cost a test
NDDB small kit	Urea, starch and flours, neutralisers, hydrogen peroxide. 20 tests	₹241, press report	About ₹12
NDDB medium kit	Urea, starch, neutralisers, salt, sugar. 500 tests	Not published	Ask NDDB
NDRI strips, sold by Delmos Research	Urea, starch, detergent, glucose, neutralisers, refined oil, hydrogen peroxide	₹10 to ₹12 a set, 2022 report	Check today's price
HT strips	Neutralisers, hydrogen peroxide, urea, glucose, maltodextrin, acidity	₹1,000 for 50	₹20 a strip
HiMedia K088B	Six adulterants. The page does not list them	₹3,365 including tax on HiMedia's own store, shown out of stock	Not listed
ISI lactometer	Density	₹150	Reusable
Lactoscan SLP analyser	Fat, SNF and more	₹24,000	Reusable
Ekomilk Ultra analyser	Fat, SNF and more	₹29,999 before tax	Reusable

NDDB's own kit page lists small, medium and large packs for household, society and plant use, and covers urea, fertilisers, starch, sucrose, glucose, salt, neutralisers and hydrogen peroxide. It gives no price, so ask them for the medium pack. For salt and detergent, the medium pack or the NDRI strips fill the gaps the small kit leaves.

For analysers in detail, see our milk analyser price guide.

How often should a centre run a milk adulteration test?

You do not need to test every can for everything. Do the sum. Five spot tests a day at ₹12 is ₹60 a day, or ₹600 on a 10-day cycle. One rejected load of 1,000 litres at ₹45 is ₹45,000. The kit pays for itself if it stops one such load in two years.

A routine that fits a typical centre:

1. Every can: smell, look, and FAT with CLR or SNF. This is already your rate reading.
2. Every day: one kit test on your mixed bulk before it leaves, and four on suppliers picked without telling them. A bulk test can miss one bad can, because the rest dilutes it, so the spot tests matter.
3. At once: test any supplier whose FAT drops while his CLR holds, or whose reading is suddenly better than his cattle allow.

If the bulk fails, work back through the cans of that shift.

If a test fails, repeat it on a fresh sample with the supplier standing there, and run clean milk beside it. A home test is a screen, not lab proof. For a repeat case, take a sealed sample to a lab before you stop buying.

Plants are stricter. FSSAI's 2019 scheme tells dairy processing plants to test every tanker or container at reception, including adulterants, and keep the records at least one year. It is addressed to plants, not village centres. We found no FSSAI rule that makes a centre log these tests for each delivery. Still, your milk ends up at that dock, so keep a notebook with date, supplier, test and result.

Doodh Master holds each supplier's FAT and CLR by date in its milk entries, which makes point 3 quick to spot. It has no field for chemical tests, so that notebook stays on paper.

What to do next

Order one kit this week and run all its tests on milk you trust, so you know what clean looks like. If you are unsure what a test result means for your rate chart, talk to us.