Drinking adulterated milk?

IIT Hyderabad researchers are developing a detector changes that changes colour according to the acidity of the milk and algorithms loaded on to mobile phones can detect this change

Are your children drinking adulterated milk? Did you know that 68.7 % of milk and milk by-products in the country are adulterated with products such as detergent, glucose, urea, caustic soda and white paint, which can lead to serious health problems? To tackle the issue researchers at the Indian Institute of Technology Hyderabad (IIT-H) researchers are developing smart phone-based sensors to detect adulteration in milk.

A detector system has been developed to measure milk acidity with the help of an “indicator paper” that changes color according to the acidity of the milk. Algorithms too are being worked out which can be incorporated on to a mobile phone to accurately detect the color change.

The findings by Prof Shiv Govind Singh, Dr Soumya Jana and Dr Siva Rama Krishna Vanjari from the department of electrical engineering, IIT-H and their team members have been published in the November 2018 issue of Food Analytical Methods journal.

Though techniques such as chromatography and spectroscopy can be used to detect adulteration, these are expensive to set up and cannot be miniaturised into low cost, easy to use devices, so they do not appeal to milk consumers, Prof Shiv Govind Singh has said.

The sensor chip based method developed by the IIT-H team will measure pH, an indicator of the acidity. A process called ‘electrospinning’ produces a paper-like material made of nanosized (~10-9 m diameter) fibres of nylon, loaded with a combination of three dyes. The paper is “halochromic”, which means it changes colour in response to changes in acidity.

Colours of the sensor strip after being dipped in milk are captured by a phone camera and data is transformed into pH (acidity) ranges through a prototype smart phone-based algorithm. Three machine-learning algorithms have been used by the IIT-H team and detection efficiencies in classifying the colour of the indicator strips are being compared. On testing with milk spiked with various combinations of contaminants, they found near-perfect classification with accuracy of 99.71%.

Studies will also be conducted now on the effects of mobile phone cameras and lighting on detection efficiency. In the long run, the researchers hope to develop sensors for other physical properties such as conductivity and refractive index, and integrate it with the pH detection unit for more accurate quality checks done quickly with easy- to-use devices.

Adulteration of milk is a serious problem in India. A recent report by the Animal Welfare Board, a statutory advisory body advising the Government of India's Ministry of Environment, Forest and Climate Change, shows that 68.7 % of milk and milk by-products in the country are adulterated with products such as detergent, glucose, urea, caustic soda, white paint and oil. Chemicals such as formalin, hydrogen peroxide, boric acid and antibiotics could also be added to milk to increase shelf life.

Consuming caustic soda or urea in milk could in the short run lead to problems gastroenteritis, but in the long run have serious health impact.

“We need to develop simple devices that the consumer can use to detect milk contamination. It should be possible to make milk adulteration detection failsafe by monitoring all of these parameters at the same time, without the need for expensive equipment,” Prof. Shiv Govind Singh has said.