New research: Using mobile vibrations to determine milk freshness

A research team at the University of New South Wales in Australia has developed a method to find out whether milk is still edible. And it does so without opening the milk carton and smelling the milk. The researchers use the smartphone vibration motor and call their method "VibMilk".

You might be wondering what the point of this is. You could simply use the milk until the best-before date expires and/or smell it. However, according to the university press release, around 20 per cent of all dairy products worldwide are thrown away even though they are still edible.

The reason for this is that the milk has a best-before date.

The reason for this is the expired best-before date. However, this date is more of a rough guide. What is more important is whether the product is stored correctly. In this case, fresh milk can last longer than stated - and conversely, it can also spoil before the best-before date if it is not stored correctly.

Milk or whey? The consistency tells the tale

Milk contains bacteria that multiply over time. This is natural and not necessarily harmful to health. However, after a certain amount of time, the bacteria transform the milk into a mixture of curd, whey and water. This changes its viscosity and pH value. Spoilt milk stinks and can cause stomach problems if you drink it.

You can usually find out whether the milk is still good by opening the carton. However, once the packaging is open, the milk is also exposed to other bacteria, which accelerates spoilage. What is normally not a problem in private households can lead to perfect milk being tipped away or, under certain circumstances, to spoilt milk being sold in larger stocks.

Test milk without opening the packaging

With VibMilk, all you have to do is place the mobile on the milk carton and let it vibrate. The vibrations are transferred to the carton and the milk it contains. Using the smartphone's IMU sensor, VibMilk can calculate the density and consistency of the milk based on the vibrations. Most smartphones have such a sensor, which analyses various values and uses them to determine the position and orientation of the device.

VibMilk displays the result as one of 23 possible pH values. This indicates whether the milk is still edible or already spoilt. Tests with four commercially available smartphones have shown an accuracy of 98.35 per cent in determining the correct pH value. Apparently, the results are even better when recognising fresh milk: the accuracy rate was 100 per cent. The study was published in the Internet of Things Journal.

Who is VibMilk intended for?

You cannot currently download the application and the press release leaves open whether this will be possible. The researchers are also aiming to work with manufacturers and charitable organisations.

However, there is still work to be done before then. According to the press release, the team is investigating the effect of different packaging materials on vibrations. As each manufacturer uses its own packaging methods, the research team would like to collaborate with other manufacturers.

The team is also researching ways in which the method can be applied quickly and automatically to large quantities of milk cartons.