A hurdle approach may help take the heat out of decontamination

By Guy Montague-Jones

- Last updated on GMT

Related tags: Food preservation, Food

The prospect of not having to use heat to decontaminate food is appealing to industry but so far non-thermal techniques have failed to make it onto many factory floors. James Lyng, senior food science lecturer at University College Dublin, expects that to change and predicts that using different techniques in combination will become a common strategy.

Lyng has been working on non-thermal technologies since 2004 and is currently involved with Food for Health Ireland investigating how non-thermal technologies may help preserve functional ingredients.

Range of techniques

Under the ‘non-thermal’ umbrella are a range of techniques including high pressure, pulsed electronic fields (PEF), ultrasound and light technologies. What they all have in common is that they do not use heat to preserve food and drink products.

As energy prices rocket that is an appealing attribute but non-thermal technologies have other advantages too; notably they help bypass the flavour, colour and nutritional damage that heat treatment can inflict.

Despite this, few have made a big commercial impact on the food industry. High pressure processing is one of the most commercially advanced of the technologies.

Used for everything from opening oysters to extending the shelf life of guacamole, Lyng said high pressure is a “fine technology”.

But because of the thick walls and high steel content of the machinery, cost is always going to be a barrier to its widespread use.

“High prices are going to make it too expensive for lower value commodities like milk but for premium products the investment can be worth it,”​ said Lyng.

Other techniques that are now well documented in the scientific literature and are making their first commercial steps include pulsed electronic fields (PEF) and light technologies.

Several companies are offering light technologies, which have the advantage of being relatively inexpensive. They encompass several different techniques including high intensity light, UV light and blue light which are at different levels of development.

Why is a hurdle approach likely?

UV light is now quite commonly used but Lyng said it does have some drawbacks. Importantly, it is only really effective at decontaminating the surface of food products and can have some negative effects on product quality such as oxidative deterioration.

Lyng said this is why ‘a hurdle approach’ is likely in the future. UV light may be used to work at the DNA level while PEF is employed to disrupt the cell membrane so by combining the two techniques shelf life can be extended further. Also, Lyng said that by using both techniques they can be used at lower levels so that damage potential (e.g. oxidative deterioration) is minimised.

The lecturer said PEF has so far made only a limited appearance in industry but there is a lot of interest and now that the FDA has approved it for use in fruit juices commercial use is likely to increase. He said PEF is comparable to conventional thermal techniques on cost.

Related topics: Processing & Packaging

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