FNB News - IIT Hyd team developing phone-based sensor to detect milk adulteration

You can get e-magazine links on WhatsApp. Click here

DAIRY PRODUCTS

IIT Hyd team developing phone-based sensor to detect milk adulteration

Thursday, 22 November, 2018, 08 : 00 AM [IST]

Our Bureau, Mumbai

A team of researchers from the Indian Institute of Technology (IIT) Hyderabad is developing a smart phone-based sensor to detect adulteration in milk. As a first step, they have developed a detector system to measure the acidity of milk through the design of an indicator paper that changes colour according to the acidity of the milk. They have also developed algorithms that can be incorporated on to a mobile phone to accurately detect the colour change.

The research team, led by Shiv Govind Singh of the department of electrical engineering, IIT Hyderabad, comprises Soumya Jana and Siva Rama Krishna Vanjari, associate professors in the same department, and others, has been published in the latest issue of Food Analytical Methods journal.

Speaking about the importance of this research, Singh said, “While techniques such as chromatography and spectroscopy can be used to detect adulteration, such techniques generally require AN expensive set up and are not amenable to miniaturisation into low-cost easy-to-use devices. Hence, they do not appeal to the vast majority of milk consumers in the developing world.”

“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,” he added.

As a first step, the research team has developed a sensor chip-based method for measuring pH, an indicator of the acidity. The researchers have used a process called electrospinning to produce paper-like material made of nano-sized (~10-9m-diameter) fibres of nylon, loaded with a combination of three dyes. The paper is halochromic, that is, it changes colour in response to changes in acidity.

The researchers have developed a prototype smart phone-based algorithm, in which, the colours of the sensor strips after dipping in milk are captured using the camera of the phone, and the data is transformed into pH (acidity) ranges. They have used three machine-learning algorithms and compared their detection efficiencies in classifying the colour of the indicator strips. On testing with milk spiked with various combinations of contaminants, they found near-perfect classification with accuracy of 99.71 per cent.

The research team at IIT Hyderabad will extend the above research to study the effects of mobile phone cameras and lighting on detection efficiency. In the long run, they hope to develop sensors for other physical properties such as conductivity and refractive index, and integrate it with the pH detection unit to obtain comprehensive milk quality check systems that can be easily deployed by the consumer using mobile phones and other hand-held devices.

Adulteration of milk is a serious problem in India. A recent report by the Animal Welfare Board shows that 68.7 per cent 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 its shelf life.

The conventional way to detect adulteration in milk is to analyse the chemicals that are present in it by complex processes. Singh’s research team seeks to detect contamination through sensing changes in the biophysical properties of milk as explained in their earlier publish work, J of Food Chemistry. Some common biophysical properties that change because of addition of adulterants are acidity, electrical conductivity and refractive index (passage of light through material).

For example, the addition of detergent, caustic soda or boric acid can make the milk more or less acidic than it should be. The addition of urea can change the electrical conductivity of milk. The addition of sugar, water and urea has been shown to alter its refractive index.