Spoilage sensors could replace use-by dates on meat and fish products

By Flora Southey contact

- Last updated on GMT

©GettyImages/Noel Hendrickson
©GettyImages/Noel Hendrickson

Related tags: Sensor, Food safety, Retailers

Researchers in the UK have developed cheap, biodegradable, and reliable food freshness sensors they say could replace use-by dates in retail stores.

Food waste is a growing concern across Europe. Around 88 million tonnes is generated across the bloc per year, at a cost of approximately €143bn.

In the UK, an estimated 7.1 million tonnes of food is wasted in households, and an alarming 260,000 tonnes at retail level, according to sustainability body WRAP.

In a bid to combat food waste, scientists at Imperial College London have developed prototype sensors that test the freshness of food. The paper-based electrical gas sensors (PEGS) can be read by retailers and consumers on smartphones to determine whether packaged meat and fish products are safe to eat.

Costing just $0.02 to manufacture, the researchers claim their tech could make for a cheap, more reliable alternative to use-by dates.  

Paper-based tech

The surprise with this discovery was that the researchers used “a single piece of paper” ​to sense the gasses, Imperial College London’s Dr. Firat Güder told FoodNavigator.

“They are very easy to make. Essentially, it is a piece of paper consisting of carbon cellulose, and two printed carbon electrodes. We measure the conductivity of the [naturally present] layer of water that is absorbed in paper on the cellulose fibres.”

Cross-section--tojpeg_1559581640829_x2
PEGS are made of carbon electrodes printed onto readily available cellulose paper ©Imperial College London

When a spoilage gas is present, such as ammonia or trimethylamine, it interacts with this layer of water and changes its electrical properties. Near field communication (NFC) tags allow for smartphones to read this alteration and alert the retailer or consumer ahead of consumption.

Importantly, the sensors require water to function, which is why the researchers are targeting the packaged food industry. “Our sensors work really well above 56-70% relative humidity,” ​Güder explained. “And the inside of food packaging is nearly 100% relative humidity.”

This research has been published by the American Chemical Society (ASC)’s Sensor journal.

Tackling food waste in retail

The end goal, according to Güder – who co-authored the study – is to reduce food waste in supermarkets and grocery stores.

Currently, data regarding food waste at the retail level is “not very reliable”, ​he explained. Yet having spoken with a number of grocers, Güder is convinced “the existing methods of doing things is not working…they throw away a tonne of food”.

The researchers are determined to succeed where others have failed. A number of companies developing colorimetric sensors for example – which discolour when food loses its freshness – “have gone under”, ​we were told. “It turns out that when retailers used colorimetric sensors, even the slightest discolouration in the packaging would signal to consumers that this is not the best food you can get, even though it’s perfectly good to eat.

“So it led to even more food waste and more losses for the retailers.”

The Imperial College London team is determined that a win-win approach will push the tech towards commercialisation. “It became obvious to me that for any tech we come up with around the food industry, the packaging manufacturers have to benefit, the retailers have to benefit, and the consumers have to benefit.

“Every single stakeholder in this ecosystem has to benefit from this.”

The researchers have launched a start-up company called Blakbear, applied for a grant, and have partnered with a packaging manufacturer to help advance the invention towards market. “Whoever is willing to help us realise this technology and make it a reality, we’re happy to work with,” ​said Güder.

GettyImages-185327906
The sensors detect the gas produced by spoiled meat and fish ©GettyImages/Vesnaandjic

Once on the market, the tech could help retailers determine how fresh their meat products are, and dynamically price their items accordingly. If food is turning, but still safe to eat, the retailer can reduce the price to have a better chance of selling stock before it becomes waste.

The sensors could also facilitate more complex dynamic pricing schemes, whereby the freshest products are sold at full-price when they first enter the store. These items could then be discounted as they lose their freshness over the following days.

Combatting food waste at the retail level would also have a number of positive, secondary effects, Güder continued, citing the reduction of plastic waste and carbon emissions.

“We’re producing food that we’re not eating, and most of the food we produce is packed in plastic. The environmental impact of food waste has many dimensions. There are secondary, third and fourth degrees of wasting food.”

Source: ACS Sensor
Published: 8 May 2019
Cellulose Fibers Enable Near-Zero-Cost Electrical Sensing of Water-Soluble Gases
DOI: https://doi.org/10.1021/acssensors.9b00555​ 
Authors: Giandrin Barandun, Matteo Soprani, Sina Naficy, Max Grell, Michael Kasimatis, Kwan Lun Chiu, Andrea Ponzoni, Firat Güder

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