Mild preservation techniques extend storage life while retaining flavour and health benefits

Try to imagine 21-day-old orange juice, which is just as healthy and tasty as the day on which it was squeezed. This is just one example of a product that can now be kept for longer with no discernible loss of quality, thanks to new mild preservation techniques. Wageningen UR Food & Biobased Research has joined forces with the business sector to examine these promising techniques.

High pressure processing is one of the techniques that have already found their way onto the market. This is an alternative method for preserving products that are traditionally pasteurised or sterilised, such as cold meats, fruit juices & drinks, and ready-made meals. The new technique neutralises micro-organisms by exposing them to a pressure of up to a thousand MPa. According to Ariette Matser, researcher at Wageningen UR Food & Biobased Research, high pressure processing is a fairly established method for preserving refrigerated products. “I would estimate that around two hundred food products on the European market are already being preserved using this high pressure method.”

Pulsed electric fields

Another technique currently making its way from the lab to market implementation is pulsed electric field-processing. This technique makes short work of micro-organisms in liquid products such as fruit juice, milk, yoghurt and soup by subjecting them to high voltage currents while they are pulsated at a low temperature. Wageningen UR Food & Biobased Research and Hoogesteeger, which leads the fresh fruit juices and smoothies market, joined up to develop the Fresh Micro Pulse, a technique that was nominated for the Food Valley Award earlier this year. It keeps fruit juice ‘fresh’ for 21 days without compromising its quality. There is a lot of interest in this technique, says Marjolein van der Glas, business development manager at Wageningen UR. “But it still needs a bit of work before producers can order tailor-made production lines operating this technique.”

Cold plasma

The cold plasma technique has even further to go before it reaches the production stage. This method uses cold gases to disinfect the surfaces of packaging or food products, and is attracting a lot of attention from the food industry. Hardly a surprise, says Ariette Matser. “There are very few options for cleaning surfaces of this kind. Many of them are not heat-resistant, cleaning with water is expensive and chemicals are often out of the question. But gas reaches every nook and cranny.”

Volumetric heating

A fourth technique currently being tried out in pilots is volumetric heating. This technique could provide a method for defrosting large quantities of food swiftly and evenly, as well as for pasteurising or sterilising certain products. It uses microwaves or radio frequencies. “The main advantage of this technique is that it is based on a very familiar mechanism: heat kills micro-organisms,” explains Ariette Matser. “But you have to be sure that the food is heated right through. There are numerous technical solutions to this problem, and we´re currently looking into them.”

What works and what doesn’t?

A previous EU study laid the foundations for further scientific research, some of which is being conducted in the Dutch government’s Agri&Food top sector. Continued research is needed to pinpoint the exact factors that affect the final results of preservation techniques. “Companies obviously want to know what works for their product and what doesn’t,” says Marjolein van der Glas. “We can help them to answer this question during PPP programmes, as well as in private projects commissioned by a specific client.”