Detecting Buffalo’s Milk in Cow’s Milk Products

Researchers develop a new rapid, simple test that can detect low levels of buffalo’s milk in cow’s milk – helping to protect consumers from fraud.

Milk is an excellent source of calcium, necessary for healthy teeth and bones. While cow’s milk is a popular choice, products are also available from other species. For example, buffalo milk is nearly twice as rich in fat compared to standard cow’s milk.

India is the largest producer of buffalo milk and the second-largest producer of cow’s milk in the world. In recent years, there has been a shift in consumer preferences towards cow’s milk, which has led to an increase in fraudulence. Adulterating buffalo milk and passing it as cow’s milk is illegal – and potentially dangerous for consumers with allergies. Dairy industries, as well as food regulators, require a simple, rapid test to detect buffalo milk in cow milk products.

A Simple and Rapid Test

Lateral flow immunoassays (LFIA) can rapidly detect the presence or absence of a specific target substance. Already established as diagnostics tools, such as in pregnancy testing, these devices are increasingly being applied for food monitoring purposes.

An LFIA typically contains a control line to confirm if it is working, along with a test line. The device incorporates an antibody that specifically binds with the desired target – and a label, such as carbon nanoparticles, which can change colour under the right conditions. A positive result is read either by the absence or presence of a coloured line at the test line. Optimising the assay is important to make sure the label interacts correctly with the antibody and target, ensuring the reliability and accuracy of results.

Detecting Adulterated Milk

In a new study, published in Food Chemistry, researchers set out to develop a rapid and sensitive LFIA that can detect the presence of buffalo’s milk in cow’s milk.¹ The researchers raised specific antibodies against buffalo milk proteins. After purification, these were connected to carbon nanoparticles and then sprayed onto a pad. They designed the LFIA so that a grey/black colour would appear on the test line if a sample is free of buffalo milk. 

The researchers evaluated the LFIA, showing the test line completely disappeared when buffalo’s milk was mixed into cow’s milk at a 5% level or higher. The team used ultrapure water generated from an ELGA PURELAB® laboratory water purification system, minimising the risk of adding contaminants that may affect the results.

Set for Real-World Application

In this study, an LFIA with carbon nanoparticles as the signal label was successfully developed for the detection of buffalo’s milk in cow’s milk. The sensitivity of the test is 5% adulteration of cow’s milk with buffalo’s milk.

The device is rapid as well as sensitive enough for use in real-world conditions, such as milk receiving stations. The test can even be applied to heated milk products, such as pasteurised milk. 

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Reference:

1. Sharman R. et al. Adulteration of cow’s milk with buffalo’s milk detected by an on-site carbon nanoparticles–based lateral flow immunoassay. Food Chem. (2021);351:129311

Dr Alison Halliday

After completing an undergraduate degree in Biochemistry & Genetics at Sheffield University, Alison was awarded a PhD in Human Molecular Genetics at the University of Newcastle. She carried out five years as a Senior Postdoctoral Research Fellow at UCL, investigating the genes involved in childhood obesity syndrome. Moving into science communications, she spent ten years at Cancer Research UK engaging the public about the charity’s work. She now specialises in writing about research across the life sciences, medicine and health.