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THE shelf life of fruit and veg could be extended by many weeks thanks to a
new edible food coating, say scientists in China and Ireland.

The scientists behind the soya-based coating have already used it to preserve
kiwi fruit for 37 days without any sign of rotting. The fruit normally lasts
just a fortnight. And they believe that consumers who are unhappy with genetic
modification and food irradiation would be more likely to accept this kind of
technology.

The coating does much the same job as packaging, only better, says Shiying
Xu, food scientist at the Wuxi University of Light Industry in Jiangsu. “Our
film can inhibit gas exchange, control respiration rate, decrease nutrient loss,
reduce evaporation and prevent the micro-organism growth that causes rotting,”
she explains.

To protect a piece of fruit, you dip it in a solution of the coating, which
dries to form a thin, transparent film. Although people usually peel kiwi fruit,
the coating has to be edible because chemicals from it could migrate through the
fruit’s skin.

The coating is a mixture of soya protein, a fatty acid called stearic acid,
and pullulan—a sugary carbohydrate which is produced by a fungus and which
forms sticky films. Xu says the coating should also work for apples, tomatoes
and peppers, but the relative amounts of each constituent would have to be
changed for each type of fruit, and that could make it expensive.

Da-Wen Sun, a food engineer working on the film at the University of Dublin,
says it’s hard to tell just how long the coating would preserve other types of
fruit, since they all have such varied shelf-lives. Citrus fruits, for example,
can last months before rotting—and that’s without the coating.

Like the supercool substitute for menthol
(see “Chilled out”), the fruit-saving film
will need to go through rigorous tests before it can be approved for commercial
use, says Britain’s Food Standards Agency.