Adulteration in milk these days has become very common. There are many ways in which milk is adulterated. Most common and by far less harmful is adding water in the milk. Apart from impurities added from water, there are few dangers in consuming such milk. To identify, adulteration from water, a simple test is milk slip test i.e. running a drop of milk on smooth or polished surface. Pure milk leaves some residue or traces behind. However, milk mixed with water addition, will simply flow out. This is by far easy the easiest.
However, these days, adulteration is done in more ways. It doesn’t matter if the milk is sold packaged or is supplied from a dairy farm, purity of milk cannot be guaranteed in any case.
To identify this adulteration, do the following test.
1- Litmus paper
Very common form of adulteration is Urea adulteration.
Take a teaspoon of milk in a small cup. Add a teaspoon of soybean or arhar (Tur Dal) powder. Mix the contents thoroughly by shaking the mixture. After 5 minutes, dip a red litmus paper in it. Remove the paper after a minute. If the litmus paper shows change in color from red to blue, it indicates presence of urea in the milk.
2- Synthetic
One more common form of adulteration is Artificial or synthetic milk.
This is one of the most dangerous form of milk adulteration.
In order to identify this type, you may follow the process as below,-
Synthetic milk gives a bitter after taste. It gives a ‘soapy’ feeling if it is rubbed between two fingers. Another indication is that, it turns yellowish on heating. With some experience, one can easily make out whether it is pure natural milk or a synthetic liquid sold as milk.
3- Skew test
Put a drop of milk on a polished slanting surface. The drop of pure milk flows slowly leaving a white stream behind it, whereas milk containing water will flow instantly without leaving mark.
4- Lather test
Take 5 to 10ml of milk and an equal amount of water in a container. Shake it up well. Lather formation indicates detergent in the milk.
5- Starch test
Add a few drops of tincture of iodine or iodine solution to a little milk. If the milk turns blue it means it contains starch. Iodine solution is easily available in medical stores.
Starch like mashed potatoes in khoya and khoya products, chenna and paneer: Boil a small quantity of sample food product in water. When the heated mixture becomes cool, add a few drops of iodine solution. If the color of the mixture turns blue it means there is starch in the food product.
6- Khoya test
Take 500ml of sample milk. Heat it till it turns in rubbery mass. Adulterated milk mass is dry while pure milk mass is shinny and non-sticky.
These simple tests at home will help you to ensure that you are consuming safe and adulterant free milk.
Milk being a vital portion of our food intake, its use is necessary even after awareness of its impurity. Regrettable, we as a consumer don’t have any choice except to own a cow.
Staff Contributor
Rabia Arshad
