'Electronic tongue' can spot milk adulteration

A technique that can establish the heat treatments undergone by milk could be used to identify mislabelled or counterfeit products, say researchers in Thailand.

The method is based on an array of biosensors that can creates a pattern of fluorescence depending on the milk proteins present in the sample, and reveals if it has undergone thermal processing that can have an impact on its nutritional quality.

While heating is generally used to destroy micro-organisms in milk and extend shelf life, if it is applied too vigorously it can denature milk proteins and compromise their nutritional value, as well as affecting other factors such as taste.

"Mislabelling and counterfeiting of milk products are international issues," according to the researchers, who note that "labels carrying false information or making misleading claims are illegal."

"It is thus of value to identify the commercial milk products according to their thermal treatments," they write in the journal Food Chemistry (15 April 2016), noting that the technique has advantages over traditional spectroscopy approaches including that t is highly sensitive and can be used for high-throughput screening.

Using the array the team were able to distinguish between different thermal processes, i.e. differentiating between pasteurised milk, sterilized milk, UHT fresh milk and recombined milk (UHT milk having milk powder) with 100 per cent accuracy. It could also tell one brand of milk from another, they report.

"This study demonstrated that fluorescent compounds can be systematically optimized as an effective electronic tongue for protein discrimination in complex mixtures," they conclude.