Shelf-life extension project gears up for commercial application

Pendred - technology Fogging in cold storage

Trials investigated how different produce reacted to the solution applied via fogging in cold store

Simple to use, a new technology involves produce being fogged with an electrically charged solution that kills the bacteria responsible for spoilage. It has also proved extremely successful in destroying e-coli bacteria. Produce Business UK finds out more

The story began five years ago when scientist and technology developer, Dr Julia Pendred, began to investigate ways of reducing spoilage in fresh produce. As suppliers and retailers are all too well aware, spoilage is a major problem resulting in the supply chain that leads to some 20% of all fruit and vegetables being lost due to contamination or damage during storage, handling and transportation which in turn leads to susceptibility to decay, and the growth of microorganisms. 

Dr Pendred is CEO of Norman Pendred & Co Ltd, which manufactures humidification and water systems providing technological solutions for the food industry. Her business specialises in techniques that maintain maintaining the moisture content of fresh produce while in cold storage and at the point of sale. 

“We develop aerosolisation technologies generating different droplet sizes such as fogging and misting systems which prevent dehydration, improve quality and increase the shelf and storage life,” says Dr Pendred. “We became interested in putting different solutions into these systems to see if they would reduce food waste caused by spoilage.  We were also interested to see if human pathogens such as E-coli could be killed in this way.  My research led me towards methods of using environment-friendly disinfectants. These were natural products with minimal environmental impact and would be safe to use.”

Research collaboration

She linked up with Professor Darren Reynolds at the Centre for Research in Biosciences and the Institute for Bio-Sensing Technology at the University of the West of England Bristol. Professor Reynolds has been undertaking interdisciplinary scientific and technological studies in the fields of health, life and physical science for the past 20 years.  Following discussions, they decided to undertake some preliminary studies, which included applying fog to fresh produce. Their research revealed that their proposed method of delivery of environment-friendly disinfectants was unique and that no one else was researching these types of disinfectant. 

The success of the initial research prompted a decision to set up a Defra-funded project involving a consortium comprising the University of the West of England, Norman Pendred, Bridge Biosystems, Fresca Group, and Thanet Earth. Norman Pendred & Company was the lead developer with Dr Pendred taking the role of project manager and industrial research lead. The project, Microbial Management of Fresh Produce Preservation, Protection and Intervention, began in 2013 and received £250,000 in funding via Defra’s Technology Strategy Board, now known as Innovate UK.

Solution on trial

The resultant trials involved investigating how different types of fresh produce reacted to the solution being applied via fogging in cold storage and misting on a conveyor belt.  Pendred’s systems ensured that during the fogging process, the disinfectant was spread evenly throughout the storage facilities due to the small size of the uniform droplets. The solution ultimately reverted to salt and water after use, making it suitable for widespread use without any environmental consequences, and reduced the need for the use of chemicals within the produce sector.

“This was a very broad project. We needed to judge at what stage in the food processing chain intervention would be most successful, and evaluate the effectiveness of the technique at each stage,” says Dr Pendred. “Different approaches were investigated during cold storage and misting on a conveyor system. The driver behind the project was to provide minimal intervention with maximum results.”

Shelf-life extended

The project proved extremely successful. The shelf life of fruit and vegetables increased by one day, and tests showed that there was no effect on the taste or appearance of the product.

Tomatoes and cucumbers responded particularly well to treatment with the electrically charged solution, created by passing salty water through an electro-chemical cell. The activated solution, which is inexpensive to make, kills bacteria commonly found on the surface of fresh produce but is harmless to human skin.  Other products successfully doused in the liquid included baby leaf, brassicas, carrots and potatoes.

Professor Reynolds says: “Ultimately, this will make the whole production, distribution and sales process more efficient.  It will allow producers to be more strategic in the way they crop and give them more time to distribute food before it goes off or gets spoiled. If you really want to change the world, one of the things you can do is extend the shelf life of a cherry tomato by one day. Such small things can actually make a huge difference in the whole food supply chain.”

Bacteria success

Bacteria proved easier to kill than mould or yeast. One of the most successful results was in the destruction of E-coli bacteria. The project revealed that not only was the method successful in killing bacteria, it had to be customized to each type of produce depending on the skin type.

“We found that it was not a one size fits all solution,” says Dr Pendred. “Tomatoes and cucumbers have a relatively hard skin with less areas where bugs can hide.  Spinach and broccoli have a different type of skin offering more space for bugs to hide.  Different contact times and intervention at different stages of the food processing chain were needed for successful results.”

Commercial application

Following the successful completion of the large-scale trials, attention has switched to investigating methods of commercialising the technology. Dr Pendred indicates that there has been considerable interest expressed within all sectors of the fruit and vegetable industry and discussions are already underway with a range of companies to develop the systems. “We aim to partner with the right companies to get the technology in place,” says Dr Pendred. “It is a slow process, as the opportunities to intervene and prevent spoilage through this method are diverse and broad across the food supply chain. We expect to have systems up and running by the end of the year.”

In the long term, this method of delivering antimicrobial solutions could have a much wider impact as Professor Reynolds points out.  “It’s possible we can apply this technology in other spheres as well, such as potato blight, which is a problem in parts of Canada.”   

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