Irradiation key to fruit and veg safety, study

[rgiridhar]

Irradiation key to fruit and veg safety, study
By Charlotte Eyre

A new study claims that irradiation is the safest method of reducing the risk of foodborne diseases such as E. coli in fruit and vegetables.

The research is likely to be of interest to fresh produce growers and retailers, as an outbreak of a foodborne disease can be extremely costly, as well as potentially fatal for the consumer.

According to the American Chemical Society, harmful microbes are "masters of playing hide-and-go seek", meaning that washing fresh produce, even with chlorine disinfectants, does not get rid of them.

Bacteria may also cling to the rind and form a "biofilm" - a mass of microbes attached to a surface which is extremely hard to remove, scientists said.

"When bacteria are protected - whether they're inside a leaf or inside a biofilm - they're not going to be as easy to kill," said Brendan Niemira, director of the study. "This is the first study to look at the use of irradiation on bacteria that reside inside the inner spaces of a leaf or buried within a biofilm."

Irradiation is a method of exposing food to a source of electron beams, creating positive and negative charges, with the aim of disrupting the genetic material of living cells.

For the experiment, Niemira and his colleagues cut leaves of romaine lettuce and baby spinach into pieces and submerged them in a cocktail mixture of E. coli.
The leaves were then treated with either a three-minute water wash, a three-minute chemical treatment - a sodium hypochlorite solution - or irradiation.

According to the study, washing the produce with ordinary water had no effect on reducing the E. coli pathogen, and the chemical solution "did not result in significant reductions".

However, ionizing radiation did have a significant effect on pathogen numbers, with reductions of 99.99 per cent on romaine lettuce and 99.9 per cent on spinach at the highest dose tested, the study claimed.

The researchers said they will continue carrying out more research into pathogens and fresh produce in the near future. One issue to consider is whether clear if pathogens can actually multiply within plant tissues, or if they merely persist, Niemira said.

"This is an important question, because if the pathogens don't reproduce effectively within these protected spaces and stay below minimally infective population sizes, then the risk they pose to consumers is less," he said. "If they are able to reproduce inside, then they may increase to more dangerous levels."

Foodborne illnesses are indeed an important area of food safety, as an estimated 76 million cases occur each year in the US alone, causing about 325,000 hospitalizations and 5,000 deaths, according to the Center for Disease Control and Prevention (CDC).

However, irradiation is a controversial food safety technique, as many regulators and members of the public remain wary on how it may affect human health.

The US Center for Food Safety has said that irradiation produces unique substances in food that may have toxic effects, and that it affects both the nutritional quality of food and characteristics of the food that make it a pleasant.

The EU seems equally skeptical, as a 2007 report from the European Commission stated that only 10 member states approve irradiation facilities to process foods.

Due to the public concerns, regulators are monitoring the situation and turning up undeclared irradiation in foods, serving to make the public even more suspicious about the technology, the report said. For example both the UK and Ireland's governments have reported finding illegally irradiated food products in 2006.