When Swede Joel Haamer first developed his valve for in-pack ultrapasteurisation (UP), his first concern was the preservation and safety of mussels. Now, it seems, the world might just be his oyster.
Established in 2000, his firm, Micvac, twinned the valve with a polypropylene tray and lidding film format and with industrial microwave processing.
The technology has since been applied to a range of heat-processed products in Sweden and other Nordic countries. In Norway, some 7M Micvac packs were sold last year alone.
Whistling Chef
As well as the UK where the 'Whistling Chef' concept and Tesco's adoption of the format recently hit the headlines the technology is being introduced into the Netherlands, Japan and the US. As UK agent Andrew Niznik puts it: "It's a great Swedish secret that's been released after 10 years."
Has it really been such a secret? Or are there sound reasons why other packaging firms have not pursued similar technology combinations?
Niznik stresses that the Micvac system is a continuous process. In this, it contrasts with high-pressure processing (HPP) and retort pasteurisation, which remain batch-driven.
At the same time, it does away with high-risk/high-care areas of the operation.
Instead, a lidding film is applied to trays loaded with pre-cooked sauces and raw protein and vegetables. Before sealing, the valve is applied to the lidding film. This vents the pack as the contents are microwaved at UP levels of 10 minutes at 90°C or equivalent.
"The valve, which is the size of a postage stamp, recloses itself after processing," said Niznik. "And, importantly, it will function more than once." This means the same self-venting mechanism works during microwave reheating in the home or workplace.
The process easily achieves a 30-day chilled shelf-life. "One of the key performance indicators (KPIs) for supermarket managers is shelf availability," he argues. "Another KPI is wastage. With this system you will have three, or even four, weekends to sell the product."
Perfect chill chain
But at Sealed Air Cryovac, technical director for ready meals Dr Sidi Chouikhi questions the need for such longevity. Unlike France, where UP is used to achieve ambient extended shelf-life (ESL) of 10 days or more, up to 95% of ready meals in the UK are short shelf-life.
"Various people have tried UP in the past and subsequently rowed back from it," says Chouikhi. "Basically, the UK has such a perfect chill chain and distribution system the best in the world that you don't need it."
You have to ask why the ESL-friendly French market has not adopted the method, with at least two operators offering microwave UP and packaging combinations in Europe (Micvac and Swiss firm Creative New Foods).
Part of the answer could lie in the fact that, according to Chouikhi, the technology only makes sense for a narrow band of products where minimal processing is required. These might include pasta, or fish with a creamy sauce "It works best where you can cook and ultrapasteurise simultaneously," he claims.
There could be other reasons for this lack of a French breakthrough. As Niznik points out, the ability of the valve to effectively create its own vacuum during processing expelling vapour and air and then resealing itself was not that easy to achieve.
Unimpressive pack aesthetics?
But Chouikhi is less than impressed with the pack aesthetics. In his experience, the process can result in the stretched lidding film sagging into the product and lighter-weight trays showing signs of crumpling. "The product can look more like a vacuum pack, without a tray-and-lid finish," he says. "It can give it a Lidl or Aldi look rather than a Waitrose one."
Of course, Sealed Air Cryovac has its own proprietary high-pressure sous-vide UP system which, Chouikhi claims, can cut ready meal processing times by 30-50%.
But while this system accounts for around 50% of ready meals in Australia, for instance, he recognises that this was only possible because it was a relatively new market.
Of the Micvac system, he says: "It has its place, but perhaps only a limited place, in the UK market. It has issues to resolve first."