Smart food packaging that slowly releases antimicrobials to kill harmful bacteria like E. coli and Listeria can keep fish, meat, fruit and veg fresher for longer, scientists who developed it say.

In laboratory tests, the pack was found to be able to extend the shelf-life of fresh fruit by around two–three days as compared to regular packaging. 

The waterproof pack — developed by researchers from Harvard and the Nanyang Technological University — looks exactly like transparent plastic.

It has the added benefit of being non-biodegradable. Therefore, it can help reduce landfill waste and food spoilage.

The team found that the biggest consumer of synthetic plastics from fossil fuels is the packaging industry, and also responsible for most of the plastic waste.

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Smart food packaging (pictured) that slowly releases antimicrobials to kill harmful bacteria like E. coli, Listeria and Salmonella can keep fish, meat, fruit and veg fresher for longer

Smart packaging for food (pictured) slows releases antimicrobials that kill harmful bacteria such as Listeria, Salmonella, and E. coli. This can help keep meat, fish and veg fresher longer

‘This invention would serve as a better option for packaging in the food industry,’ said paper author and bioengineer Mary Chan-Park of the Nanyang Technological University, Singapore.

“It could replace petroleum-based polymers in commercial food packaging such as plastic, that have a substantial negative impact on the environment.

‘Smart release antimicrobials happens when high levels of bacteria are present. It provides protection only when needed — thus minimising the use of chemicals and preserving the natural composition of the packaged foods.

‘It has demonstrated superior antimicrobial qualities in combating a myriad of food-related bacteria and fungi that could be harmful to humans — [and] can be applied to various produces such as fish, meat, vegetables and fruits.’

She explained that vegetables are especially prone to wastage, as even when they’re refrigerated they still breathe, which can lead to spoilage within a few weeks.

‘With the anti-microbial packaging, there is a chance to extend their shelf life — and also make the vegetables and fruits stay looking fresh with time.’

The smart packaging material is made via a process called electrospinning, in which charged threads of polymer solution are drawn out into fibres.

The main ingredient for the material is a type of corn protein called ‘zein’ — which is a waste by-product in the production of ethanol from corn starch or oils — to which the researchers added the plant starch cellulose and acetic acid.

The team infused these with a cocktail of natural antimicrobial compounds derived from plants, including thyme oil and citric acid, which is found in fruits like grapefruit, lemons, limes and oranges.

Laboratory tests showed that only a small amount of antimicrobials were released from packaging materials when they are exposed to high humidity levels or enzymes produced by bacteria.

The team stated that the only time the compound is released in the event of potential spoilage is when the packaging has been exposed to multiple exposures and can remain functional for several months.

Tests showed that the packaging could kill various types of bacteria such as Listeria and E. coli.

And strawberries wrapped in the smart pack remained fresh for seven days before developing mould — as compared to just four days for those fruit kept in conventional plastic fruit boxes.

The material making up the smart pack (the production process for which is depicted left) is composed of a combination of starch, a type of corn protein called 'zein' and other naturally derived biopolymers — which the team infused with a cocktail of antimicrobial compounds derived from plants. In laboratory tests, the team were able to show that these antimicrobials are released in miniscule amounts from the fibres in the packaging material when exposed to either a rise in humidity (bottom right) or enzymes released by harmful bacteria (top right)

 The material making up the smart pack (the production process for which is depicted left) is composed of a combination of starch, a type of corn protein called ‘zein’ and other naturally derived biopolymers — which the team infused with a cocktail of antimicrobial compounds derived from plants. These antimicrobial compounds are only released from packaging materials when they’re exposed to humidity or harmful bacteria enzymes.

The waterproof pack — developed by researchers from Harvard and the Nanyang Technological University — looks exactly like transparent plastic. Pictured: bioengineer Mary Chan-Park park poses with one of the smart packs, which contains two strawberries. In tests, the new material kept the fruit fresh for three days longer than normal plastic packaging

The waterproof pack — developed by researchers from Harvard and the Nanyang Technological University — looks exactly like transparent plastic. Pictured: bioengineer Mary Chan-Park park poses with one of the smart packs, which contains two strawberries. The new packaging kept fruit fresher for 3 days more than regular plastic.

Philip Demokritou, a Harvard University researcher and paper author, stated that food safety and waste are a significant societal problem of the present with enormous public health consequences and economic impacts which can compromise food security.

“Effective biodegradable, non-toxic packaging is one of the best ways to improve food safety and minimize food spoilage.

“In this study we used natural-derived compounds, including biopolymers and non-toxic solvents, and developed scalable systems for synthesised smart antimicrobial material.

These, he added, ‘can be used not only to enhance food safety and quality but also to eliminate the harm to the environment and health and reduce the use of non-biodegradable plastics at a global level and promote sustainable agri-food systems.’

In tests, the packaging was capable of killing various common bacteria including E. coli and Listeria, as well as fungi, on both the surface of the packaging and the food contained within it. Strawberries wrapped in the smart pack remained fresh for seven days before developing mould — as compared to four days for those kept in conventional plastic boxes (like pictured)

The packaging proved to be capable of eliminating common bacteria like Listeria and E. coli, and fungi on the surfaces and food within. Strawberries wrapped in the smart pack remained fresh for seven days before developing mould — as compared to four days for those kept in conventional plastic boxes (like pictured)

'This invention would serve as a better option for packaging in the food industry,' concluded Professor Chan-Park, who is pictured here with her colleague Suresh Kumar Raman Pillai

‘This invention would serve as a better option for packaging in the food industry,’ concluded Professor Chan-Park, who is pictured here with her colleague Suresh Kumar Raman Pillai

Peter Barber — the CEO of Singapore-based urban rooftop farming firm ComCrop,  who was not involved in the present study — said that the material could ‘serve as a sustainable solution for companies like us who want to cut down on the usage of plastic and embrace greener alternatives.’

ComCrop is looking to increase product production in Singapore, so the packaging volume we require will rise. Switching to material like this would make a significant difference.

We would be well served by the antimicrobial properties of wraps, which can potentially increase shelf life for our vegetables.

“The industry holds great promise for packaging materials, and we are looking forward to finding out more and adopting the wrappers to our use.”

The team has completed their first proof-of concept and are looking for an industrial partner to help them scale up their technology.

They have said that they hope to be able to bring a commercial product to market within a few years.

The full findings of the study were published in the journal ACS Applied Materials & Interfaces.

TIPS ON HOW TO PREVENT FOOD POISONING

1. Make sure your work environment is clean

Germs are able to survive on all surfaces of the kitchen. It is important that you keep your cooking areas clean.

2. Avoid cross-contamination

If not separated, raw meats, poultry, eggs, and seafood can transmit germs to prepared-to-eat food items.

For handling such ingredients, it is recommended that separate cutting boards be used and plates are kept.

You should keep them separate in your fridge.

3. A thermometer is a good choice

Food safety is dependent on the cooking temperature.

A food thermometer is the best way to determine if your food has reached the right internal temperature.

4. Properly store food

Properly storing food is crucial to combat 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. Rely not only on expiration dates

The expiration date is not the only indicator of when food items should be thrown away.

It’s best to throw away anything that has a peculiar smell or color.

6. Frozen food shouldn’t be thawed on the counter.

Freezing frozen food on the counter can allow bacteria to quickly multiply in their outer parts once they reach room temperature.

You can thaw frozen foods in the fridge, cold water or the microwave.