science

Sensors that cost PENCE to produce can detect gasses from spoiled meat and fish 


Smartphones could soon tell your when food has gone off, thanks to a new sensor that costs pence (cents) to produce.

Freshness sensors that can be linked to the devices developed by British scientists can detect gasses from spoiled meat and fish.

The cheap and eco-friendly gadgets will reduce food waste and plastic pollution – and may even bring down prices for shoppers, according to a new study.

Embedded in packaging, they may replace ‘best before dates’ in meat and fish ‘within three years.’ They could also be applied to dairy goods and other produce.

Smartphones could soon tell your when food has gone off, thanks to a new sensor that costs pence (cents) to produce. Freshness sensors that can be linked to the devices developed by British scientists can detect gasses from spoiled meat and fish

Smartphones could soon tell your when food has gone off, thanks to a new sensor that costs pence (cents) to produce. Freshness sensors that can be linked to the devices developed by British scientists can detect gasses from spoiled meat and fish

Study lead author Dr Firat Guder, of the department of bioengineering at Imperial College London, said: ‘Although they are designed to keep us safe, use-by dates can lead to edible food being thrown away.

‘In fact, use-by dates are not completely reliable in terms of safety as people often get sick from foodborne diseases due to poor storage, even when an item is within its use-by.’

One in three UK consumers throw away food solely because it reaches the use-by date.

But 60 per cent, or 4.2 million tonnes, of the £12.5 billion-worth ($15.9 bn) of produce we discard annually is safe to eat.

Dr Guder said: ‘Citizens want to be confident their food is safe to eat, and to avoid throwing food away unnecessarily because they aren’t able to judge its safety.’

The prototypes cost less than two pence each to make. Known as paper-based electrical gas sensors (PEGS), they detect tell-tale gases.

These include ammonia and trimethylamine that signal when meat and fish is no longer fit for human consumption.

The data is read by people simply holding a smartphone up to the packaging.

Dr Guder said: ‘These sensors are cheap enough that we hope supermarkets could use them within three years.’

The cheap and eco-friendly gadgets will reduce food waste and plastic pollution - and may even bring down prices for shoppers, according to a new study

The cheap and eco-friendly gadgets will reduce food waste and plastic pollution – and may even bring down prices for shoppers, according to a new study

The sensors were created by printing carbon electrodes onto readily available cellulose paper.

The biodegradable materials are non toxic, so they don’t harm the environment and are safe to use in food packaging.

They are also fitted with ‘near field communication’ (NFC) tags – a series of microchips that can be picked up by nearby mobile devices.

During laboratory testing on packaged fish and chicken, PEGS picked up trace amounts of spoilage gases quickly and more accurately than existing alternatives, at a fraction of the price.

They could also eventually replace the ‘use-by’ date – a less reliable indicator of freshness and edibility.

Lower costs for retailers may also eventually make food cheaper for shoppers, say the researchers.

Dr Guder pointed out that PEGS are the first ever commercially-viable food freshness sensors.

He said: ‘ Our vision is to use PEGS in food packaging to reduce unnecessary food waste and the resulting plastic pollution.’

The study found that consumers rely on use-by dates or even ‘sniff tests’ to see if their food is safe to eat.

But there is currently no commercially viable, reliable alternative to these options that provides objective feedback on food freshness and safety.

Although developed by food technologists over many years to ensure safety, use-by dates don’t take storage and processing conditions of specific items into account.

This can lead to safe and edible food being thrown away by shops and consumers. In addition, most of the food wasted is packaged in plastic – fuelling our polluted oceans.

First author Giandrin Barandun, who is based in the same lab, said: ‘Use-by dates estimate when a perishable product might no longer be edible – but they don’t always reflect its actual freshness.

‘Although the food industry – and consumers – are understandably cautious about shelf life, it is time to embrace technology that could more accurately detect food edibility and reduce food waste and plastic pollution.’

As PEGS work on high-value items like meat and fish, they could save money for shops and their customers.

They will cut waste and enable shops to use targeted price reduction for specific items based on PEGS rather than use-by dates.

Embedded in packaging, they may replace 'best before dates' in meat  (pictured) and fish 'within three years.' They could also be applied to dairy goods and other produce (stock image)

Embedded in packaging, they may replace ‘best before dates’ in meat  (pictured) and fish ‘within three years.’ They could also be applied to dairy goods and other produce (stock image)

Existing food spoilage sensors are not commonly used because they are either too expensive, often comprising a quarter of overall packaging costs, or too difficult to understand.

Colour-changing sensors could in fact increase food waste as consumers might interpret even the slightest colour change as ‘bad food’.

The PEGS technology aims to address both these issues. As well as being cheaper and easier to interpret with electrical readings, they overcome many of the disadvantages of current gas sensors.

Benefits include functioning effectively at nearly 100 per cent humidity, where most sensors struggle above 90 per cent.

They also work at room temperature and do not need to be heated, so they consume very low amounts of energy.

Other improvements are being sensitive only to the gases involved in food spoilage, whereas rival designs can be triggered by harmless chemicals.

What is more, the researchers only needed ballpoint pens and robotic cutters to create them.

Dr Guder said: ‘We believe our very simple technique could easily be scaled up to produce PEGS on a mass scale by using existing high-volume printing methods such as screen printing and roll-to-roll printing.’

The researchers hope PEGS could have applications beyond food processing, like sensing chemicals in agriculture, air quality, and detecting disease markers in breath like those involved in kidney disease.

But before they can be applied beyond their current use, they hope to address how sensitive PEGS are to lower humidity.

They are now testing them on other industries by developing an array of PEGS in which each sensor detects a different chemical.

The research team said it would make the technology applicable to a wider variety of food types and applications.

The full findings of the study were published in the journal ACS Sensors.

WHAT TIPS CAN BE FOLLOWED TO AVOID FOOD POISONING?

1. Keep a clean work space

Germs can survive across all of the different surfaces in the kitchen, so it’s essential to keep the cooking area and your hands clean.

2. Avoid cross-contamination

Raw meat, poultry, seafood and eggs can spread germs to ready-to-eat foods if not kept separate.

The CDC recommends using separate cutting boards and plates when handling these ingredients.

They should also be stored separately in the fridge.

3. Use a thermometer

To cook food safely, the internal temperature must get high enough to kill the germs that could cause food poisoning.

The correct internal temperature varies by ingredient, and only surefire way to tell if food is safely cooked is to use a food thermometer.

4. Store food properly

Storing food properly is essential to combating harmful bacteria.

Perishable food should be refrigerated within two hours of when it was purchased, and the refrigerator should be set to below 40°F.

5. Don’t rely solely on expiration dates

Expiration dates aren’t the only indication of when a food item should be thrown away.

If something seems to have a strange smell or color, it’s probably better to be safe and pitch it.

6. Don’t thaw frozen food on the counter

Thawing frozen foods on the counter allows bacteria to multiply quickly in the outer parts as they reach room temperature.

Frozen foods should be thawed in the refrigerator, in cold water, or in the microwave.



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