Just how fresh is that meat? A sensor can soon help you find out ...

... And curb food waste in the process, use-by date notwithstanding

Beef at 1004 Gourmet in the Greens. Photo: Chris Whiteoak / The National
Beef at 1004 Gourmet in the Greens. Photo: Chris Whiteoak / The National

The problem with a once-weekly grocery shop is that many fresh foods don’t last the entire work week. Or so shoppers are led to believe by the “use-by” dates on seafood, meat, poultry and dairy items. As a result, many don’t buy a particular item leading to a surplus at the supermarket, or think they have to throw it out if it’s not cooked by a certain date. Food waste ensues, either way.

In fact, researchers from Imperial College London estimate that one in three consumers in the UK throws food away, but that 60 per cent of the amount discarded is safe to eat. That’s a staggering 4.2 million tonnes of perfectly good nosh being washed down the drain annually.

The same team of scientists have constructed food freshness sensors, which can detect “spoilage gases” in meat and fish. The prototype devices – called paper-based electrical gas sensors (Pegs) – can detect whether the ammonia, trimethylamine and other harmful gases have indeed seeped into the item no matter its use-by date.

Sometimes, the date may indicate a product is still edible, but poor storage conditions could have started the perishing process, leading to a poor tummy or worse anyway.

The date from the sensors is easily linked to smartphones, so all consumers have to do is hold their phones up to the packaging to gauge whether the food is still safe to eat. The sensors are constructed from biodegradable cellulose paper imprinted with carbon electrodes, thereby also reducing the reliance on plastic.

“Use-by dates estimate when a perishable product might no longer be edible, but they don't always reflect its actual freshness. Although consumers are understandably cautious about shelf life, it's time to embrace technology that could more accurately detect food edibility, and reduce food waste and plastic pollution,” said Giandrin Barandun, one of the authors of the study from Imperial’s Department of Bioengineering.

“These sensors are cheap enough that we hope supermarkets could use them within three years,” added lead author Dr Firat Guder. The study, which was published in ACS Sensors on June 5, lists the manufacturing cost at two cents per sensor .

Published: June 9, 2019 03:50 PM


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