Supermarket fruit and veg can be one year old
While supermarkets are now geared up to supplying fresh produce year-round, some may have been treated with chemicals to keep them fresh for months.
Horticultural expert, Professor Michael Hennerty, said a gas treatment called SmartFresh, not yet available in Ireland, has been used on imported apples for a number of years.
The gas contains a chemical that halts the production of the hormone ethylene - a natural ripening agent. It is also used on pears and bananas that are shipped while still green and then ripened quickly using ethylene gas.
The gas is used in low doses on potatoes to preserve them for up to nine months, while sulphur dioxide pads are used on grapes to kill yeasts and other fungi.
In many cases, the treatment is combined with controlled storage that eliminates oxygen, which is necessary for fruit to ripen, and introduces high levels of carbon dioxide to preserve food - including citrus fruits.
Prof Hennerty said the chemical compound, known as SmartFresh, was patented in 1995 and has been in use commercially for the last few years. He explained that fruit is treated with the gas for 24-hours after it is harvested.
"In the case of apples, depending on the variety, it can last for around eight months," he said.
Prof Hennerty added that the treatment does not affect nutritional content and that toxicology reports indicate that it is extremely safe.
SmartFresh is not available commercially in Ireland and would probably not be used by apple growers here, who mainly pick and sell their produce immediately.
The use of SmartFresh is legal in countries that export apples to Ireland including the US, Mexico, Chile, Argentina and South Africa.
Superquinn's nutrition advisor, Paula Mee, said she was shocked that apples were being treated with a chemical to preserve them for up to a year.
"The local producer down the road is definitely preferable to an alternative, lower priced product that has travelled half way around the world," she said.
General manager of Dublin Meath Growers, Pat O'Connor, said they dealt solely in loose, fresh vegetables and salads.
* SmartFresh - preserves apples up to one year, tomatoes for two weeks and bananas for one year.
* Controlled atmosphere - preserves pears for four months and oranges for two months.
* Modified atmosphere packaging - packaging contains reduced levels of oxygen to stop salad leaves washed in a weak chlorine solution from maturing and going brown.
* Sulphur dioxide pads - preserve grapes for up to one month by killing yeasts and other fungi.
* Refrigeration - keeps kiwi fruit fresh for eight months, lettuce for nine days and carrots for one week.
