The UV rays inactivate E. coli bacteria by degrading their cell walls and DNA. These rays can be produced by high intensity fluorescent lamps, which are both cheap and readily available, making this method extremely efficient. With the optimal fluid depth and UV dose, the scientists reported a significant decrease in active E. coli bacteria in both apple juice and liquid egg white.
The researchers also found that, in direct contrast to pasteurisation, the sensory quality of the food products following irradiation was not compromised, and that inactivation of the bacteria lasted for the entire shelf life of the product. Heat pasteurisation can often affect both the flavour and consistency of food.
The scientists working on the project are hopeful that this represents a breakthrough in the fight against food-borne diseases. The presence of E.coli bacteria for example, found in foods such as egg white and apple juice, is an ongoing major public health concern.
"UV irradiation offers a relatively inexpensive and effective means of inactivating some of the serious bacteria in food products," said Dr Michael Ngadi, co-author of the study. "We are able to design and operate systems that can process liquid products to satisfy regulatory requirements. The wonderful thing is that products can be processed at lower temperatures and therefore the fresh-like quality of the product can be maintained."
There is, however, a notable degree of opposition to irradiated foods on both sides of the Atlantic. In September for example, a US politician tried to push through a bill in the US senate that would have allowed for a clear labelling policy on irradiation in the National School Lunch Programme. Representative Barbara Lee said that she was willing to sponsor a right-to-know bill on irradiated food in an attempt to give parents and children the opportunity of whether or not to choose irradiated foods.
This issue has also awoken concerns in the European Union. Recent experiments funded by the EU determined that 2-ACBs promoted the growth of colon tumors in rats and caused genetic damage in human cells. In addition to raw and cooked ground beef, 2-ACBs have been detected in other foods that the FDA has legalised for irradiation, including chicken, eggs and mangoes.
But this view is not shared by everyone. Advocates of irradiation maintain that the technology is safe and that it successfully eliminating harmful bacteria. "Dangerous substances do not appear in foods when irradiated as approved," says a statement from the Centers for Disease Control and Prevention on Surebeam's website. "This is clearly shown by extensive studies on the effects of irradiation on food, and on the animals and people eating irradiated food."