IISc researchers use novel method to detect adulterants in milk

Bengaluru: By analysing deposition patterns after evaporation, the Indian Institute of Science (IISc) have developed a low-cost and effective method to detect adulterants in milk. Existing methods like lactometer and observing changes in the freezing point of the milk is limited and other approaches are costly.

The method was designed by the postdoctoral researcher, Virkeshwar Kumar and Susmita Dash, Assistant Professor in the Department of Mechanical Engineering and the study was published in the science journal, ACS Omega.

The team utilised the technique to test the presence of urea and water in milk. They believe that the same method can be used to detect other adulterants. Adulteration of milk is a pressing concern in developing countries like India, where a majority of supplied milk fails to comply with the standards set by the Food Safety and Standards Authority of India. Water is frequently added to increase the volume of milk, along with urea, which makes the watered-down version whiter and foamier – this can potentially endanger the normal functioning of the liver, heart, and kidneys. The researchers observed evaporative deposition patterns and devised a novel method. When liquid milk completely evaporates, volatile components dissipate and the solids components arrange themselves in patterns. Milk with or with water or urea displaced stark differences in patterns.

Unadulterated milk consisted of a 'central, irregular blob-like pattern' and water was found to distort the pattern. The presence of urea erases the central pattern but being a non-volatile component it crystallises at the interior of the milk drop and extends along the boundary.

Existing methods such as lactometers and observing changes in the freezing point of milk are quite limited. The freezing point technique only covers 3.5 per cent of the total milk concentration. Biosensors used to test for urea are expensive and their accuracy decreases over time. "It does not require a laboratory or other specialised processes, and can be easily adapted for use even in remote areas and rural places." said researcher Virkeshwar Kumar.

Researchers believe that this low-cost technique has the potential to scan adulterants in other beverages and products too. "The pattern that you get is highly sensitive to what is added to it. The method can be used to detect impurities in volatile liquids. It will be interesting to take this method forward for products such as honey, which is often adulterated." explained Assistant Professor, Department of Mechanical Engineering, Susmita.

Once you derive the pattern for all adulterants and the combinations are standardised, the test can be automated by feeding the data into an image analysis software. By comparing the photographs of the patterns, researchers hope to detect the presence of adulterants.