The director of Waterwise, Jon Fielder, has expressed his concerns over inaccurate information about modified atmosphere packaging (MAP) which has swept the nationals.

In a letter to freshinfo, Fielder said: 'Reports in The Daily Mail, The Sunday Times and the British Journal of Nutrition have commented on research findings by US scientists at Cornell University that modified atmosphere packaging (MAP) is destroying vital vitamins and protective anti-oxidants in pre-washed, ready-to-eat bags of salad. This information is inaccurate and highly misleading for retail buyers and consumers.' MAP is based on using inert gases, principally nitrogen, to exclude oxygen from the packaging. This prevents biological activity and spoilage in the packet. As oxygen is excluded from the modified atmosphere gas it cannot be responsible for oxidation of the vitamin C and other nutrients as stated in the reports.

'It is commonly acknowledged that MAP does have an effect on the depletion of the nutritional value of salad, however it is the chlorine used by most UK packaged salad producers in the washing process which has a far worse effect on consumer health,' said Fielder. 'Alternatives to chlorine used on organic production such as citric acid and other organic biocides can be equally as damaging.

'In most cases, the salad leaves are immersed in water with high levels of chlorine, which is an oxidising disinfectant. The chlorine level is usually maintained at a minimum of 50 mg/l – a staggering 20 times higher than in the average swimming pool.

'As well as destroying taste and flavour, the chlorine leaves significant levels of chemical residues on the leaf surface. At Waterwise we manufacture units, which add ozone to water. This technology is ideally suited to washing salads, and has already been adopted in the Netherlands and Germany.

'Ozonated water is as good a method of disinfection and cleaning as chlorinated water but it does not leave any residual chemicals on the product surfaces. It also meets the requirements for organic production in most countries.

'The modified atmosphere packaging process is necessary to prolong the shelf life of the salad, but washing it in chlorinated water is not. When will the UK processing industry wake up to the benefits of alternative methods as their European counterparts have? '