We all have had that moment. You boil milk and it tastes watery, or it foams like dish soap, or it just does not set curd properly. Is it just your imagination?
In India, milk is one of the most commonly adulterated foods because demand is so high. The most common issues are added water to increase volume, starch to make thin milk look thick, and detergent or synthetic solution to add whiteness and foam. Home tests cannot confirm adulteration like a lab, but they are great for awareness and for deciding if you should change your source.
Here are 5 easy screening methods taught by food safety educators. Use small quantities and clean utensils.
1. The Slanting Surface Test for Water
Put a drop of milk on a clean, polished vertical surface like a steel plate. Pure milk flows slowly and leaves a white trail. Milk with a lot of added water flows quickly and leaves almost no trail.
2. The Iodine Test for Starch
Take 2-3 spoons of milk, boil it, let it cool completely. Add 2-3 drops of tincture iodine. If the milk turns blue-black, it suggests presence of starch. If it stays yellowish-brown, starch is likely not added. Do not taste milk after adding iodine.
3. The Shake Test for Detergent
Take equal parts milk and water in a clear bottle, shake well for 30 seconds. Pure milk will form a thin foam that disappears quickly. If a thick, soapy lather stays for a long time, it can indicate detergent-like residue.
4. The Curd Test
Set a small bowl of curd with your daily milk. Pure milk sets into firm, slightly sour curd in 6-8 hours in warm weather. Adulterated or highly diluted milk often sets into watery, slimy curd or does not set at all.
5. The Boiling and Residue Check
Boil milk and see what is left in the vessel. Pure milk leaves a creamy residue that is easy to clean. Milk with added solids like urea or starch can leave a gritty, sticky residue and a slightly bitter or salty aftertaste.
What to do if you suspect something
Do not panic and do not accuse the seller based only on home tests. These are indicative, not confirmatory. Switch to a pack with a valid FSSAI license number, check the manufacturing date, always keep milk refrigerated at below 5°C after boiling and cooling, and if you want final confirmation, send a sample to an FSSAI-notified lab in your state.
Saveable Checklist for Readers
Buy from FSSAI licensed vendors only, refrigerate quickly, boil what you need, observe taste, curdling and foam, and when in doubt, test and switch.