Oxygen could be the preservative of choice for organic growers in the future, extending shelf lives, with no negative health side-effects.

Edna Pesis and a team at the Volcani Centre in Israel have devised what they expect to be an effective and cheap technique to keep apples in cold storage for longer.

A simple week long pre-treatment with low levels of oxygen at 20C was shown to prevent scald formation - a type of chilling injury associated with prolonged cold storage.

Pesis said that 90 per cent of the treated apples were "saved from the scald problem in addition to other physiological diseases" after eight months of cold storage.

All of the untreated apples were lost after eight months under the same conditions.

Pesis says that the technique can be tweaked for use with avocados, tomatoes and other organic produce.

The research was published in the Journal of the Science of Food and Agriculture and reported on in Chemistry & Industry, the magazine of the Society of Chemical Industry.

Currently UK shoppers have to pay twice as much for some organic products, reports Lisa Richards in Chemistry & Industry.

Organic apples, for example, are around double the price of conventionally-grown apples in Sainbury's, Waitrose and Tesco, Richards found.

"One of the major contributing factors affecting the price is the short shelf life of organic produce," she said

"Conventional produce can be treated with inexpensive chemicals to aid preservation.

"But these cannot be used for organic produce, as by definition no artificial chemicals are used during processing."

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