My daughter came to me this morning and asked if she could use the milk in the fridge on her porridge. “The expiry date was yesterday,” she said. “Is it safe to use?” I did as any caring parent who wanted to avoid an early morning trip to the supermarket would do, and answered with “they always build in a safety margin so it will be right to drink” hoping that I was correct and wasn’t about to subject my daughter to some horrible illness.

The use by and best before dates printed on foods are the responsibility of the food supplier. There are so many variables with how the food is stored and how well it is sealed after opening that the dates printed on the packaging are naturally very conservative.

That conservative nature leads to a significant amount of food waste.

What we really need is a definitive answer. Is this particular food item safe to eat?

It is not surprising that researchers have been working on exactly this issue, and a group of scientists from Singapore, in collaboration with teams from China and Australia, have developed an e-nose specifically for the decay of various meats.

The e-nose relies on 2 components. Firstly, a twenty-segment barcode is placed inside the packaging of the meat. As the meat decays, the various lines on the barcode change colour in reaction to the gases produced. The concept was based on trying to mimic our noses. When we smell meat that is decaying, the odours bind to receptors in our nose which generate specific signals that are transmitted to our brain to tell us that meat is ‘off’.

In the e-nose the bars on the barcode act as the receptors. Each bar is made of a natural sugar embedded on cellulose and loaded with a different type of dye. As the type and concentration of gases are emitted, the various bars change colour. The unique combination of colours serves as a ‘scent fingerprint’ to indicate the state of decay of the meat.

It would be possible to have a chart that outlined colour combinations of the barcode that you could use as a reference to determine the state of your meat. But that would be clumsy at best.

Enter the second crucial component.

Your smartphone. By using the app developed by the researchers you simply point your phone’s camera at the barcode and it will give you an accurate reading of the decay level of your meat. The app is powered by Artificial Intelligence (AI) and initially chooses from a large library of barcode colours but is also continuing to learn more as it is exposed to more tests. The initial work involved 3,475 barcode images and, just with that sample size, the accuracy of the system was rated at 98.5 per cent. As more barcodes are read from more samples, that accuracy will increase.

The ultimate aim? Your daughter working out the freshness of food? Sure, that is one thing, but the real aim is to reduce food waste across the world. In Australia alone, we waste over seven million tonnes of food each year which costs the economy $20 billion and accounts for more than five per cent of Australia’s greenhouse gas emissions. Not all of this waste is in meat which is what the e-nose is specifically focused on. But it is a start – and I am sure we will see other technological advances in relation to this ongoing problem.

Tell me if you would trust an e-nose to tell you if food was safe to eat at

Mathew Dickerson

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