Feel the pulse

Watch out for the terms pulsed electric field (PEF), high pressure processing (HPP) and cold plasma. They may sound like they have been lifted from Philip Pullman's latest sci-fi novel but they will be the eco-friendly novel food manufacturing "processes of the future", according to Huug de Vries, project co-ordinator NovelQ and manager of the University Wageningen's Food Technology Research Centre.

The university plays a central role in the EU-funded NovelQ project, which is designed to stimulate innovation in novel food processing and packaging. Since the project began in 2008, it has gained over 50 cross-sectional project partners including equipment suppliers, food manufacturers and educational institutions. During its life, which is expected to run until 2011, the project represents an opportunity to enhance Europe's competitive advantage in the global market place. Studies are aimed at helping manufacturers achieve better ways of creating new and improved products, preserving foods, killing pathogens, as well as reducing electricity costs and encouraging more sustainable processing techniques.

The details of some of the latest NovelQ findings were presented at the 8th World Food Technology and Innovation 2009 conference in October. "At the moment, we are working with different partners to develop cold plasma equipment to assess the effects of the process on product quality and shelf-life, for example," de Vries said. "Cold plasmas gases to which an electric charge has been applied offer the possibility to inactivate micro-organisms on the surface of products and packaging materials, such as salmonella in chicken."

The technology is very energy-efficient, while causing minimum damage to the product, he added. "For products such as cut vegetables and fresh meat there is no mild surface decontamination technology available at the moment, but cold plasma can be used for this purpose ... I predict that the industry is about four years away from using this technology on a large commercial scale, but I believe it is the future of food processing."

At this stage, he continued, it's too early to say how much the technology will cost, "but we have high hopes that it will be low and used widely, as it requires a low energy input"

Another technology the university has been experimenting with is PEF. This is a method for processing food and drink with brief pulses of a strong electric field. The technology works particularly well for fruit juice applications for extending shelf-life and has the potential to be used as a low-temperature pasteurisation process for sterilising food products.

Costing around euro 0.01 per litre, PEF is a low-cost, low-energy technology, according to de Vries, who has high hopes for its future. His vision is that this type of technology will have the potential to be used in third world countries to sterilise drinking water because it uses a small amount of electricity and can be powered by solar energy. It also has benefits for food and drink processors in the UK: "In the food industry, it could save manufacturers a lot of money, as electricity costs only continue to go one way."

The university houses a pilot facility, which can process up to 300l an hour in this way. "Again, we believe this will be the technology of the future," he added. Alongside the PEF equipment, the university also has a HPP unit. Pressures of up to 10,000 bar can be applied to liquid or food at temperatures between 0°C and 121°C.

HPP technology can be used to modify the characteristics of starch and proteins so that they have gel like properties. The modified ingredients can then be used in products such as soya-based meat replacers, in the production of pectin gels or jams and for the tenderisation of meat.

High pressures, sometimes alongside high temperatures, can also be used to increase the shelf-life of food. Small molecules associated with flavour, colour and taste are not altered, but, under the high pressures, enzymes and microrganisms are inactivated. The university, for example, has managed to increase the shelf-life of oysters to four weeks without altering the quality. But de Vries said that this is an expensive technology, which costs around euro 0.12 per litre.

In carrots, studies also showed that HPP inhibited the effects of high temperature on texture, and its cells remained intact. Shelf-life was, therefore, increased while giving the perception of freshness. "This technology, however, is often rejected by industry as it is perceived to be expensive and complicated they also worry about consumer perception," he added.

Novel processes in action​

One large food processing company uses this technology commercially to manufacture ready meals. Maple Leaf which comprises four manufacturing ready to eat, four poultry and three pork slaughter facilities was one of the first companies in Canada to install the equipment in one of its factories, claimed Ron Judge, vice president of food safety and quality assurance at Maple Leaf. He estimated that there were now around five or six manufacturers in Canada that have HPP equipment in-house. "It's still very niche," he said.

The equipment cost Maple Leaf over £2M, as well as another £1M to install and integrate with production lines. It is used to increase the shelf-life of ready meals from 15 days to over 63 without affecting the quality, taste or texture of food.

He said that because Canada is such a big country, retailers required a longer shelf-life on products because they can sometimes take a long time to travel across the country.

The problem with the technology, however, he added, is that it can only process 150 meals at one time and the process itself takes around 10 minutes so outputs are very low. "I think that the technology would be much more popular if there was some way to increase outputs," said Judge.

"For example, one of our competitors, which does not use HPP technology, and makes frozen ready meals, produces more than 2M meals a day. It can produce meals that cost $1 Canadian dollars each, whereas we charge $3.99.

"The machinery also takes up a lot of space in the factory. The HPP unit alone is at least 5m long," he added. "While HPP is an exciting technology, novel processes are still very much in their infancy. Much more research is needed before they are widely used in food and drink processing." FM