Washing fruits and vegetables does reduce the risk of food poisoning. However, washing alone may not be enough.
Studies show that some disease-causing microbes can evade even chemical sanitizers. These bacteria can make their way inside the leaves of lettuce, spinach and other vegetables and fruit, where surface treatments cannot reach them. Microbes can also organize themselves into tightly knit packs called biofilms to protect themselves from harm.
Biofilms can harbor multiple versions of infectious, disease-causing bacteria, such as Salmonella and E. coli.
Researchers suggested that irradiation, a food treatment that exposes food to a source of electron beams, could effectively kill internalized pathogens that are beyond the reach of conventional chemical sanitizers.
Irradiation disrupts the genetic material of living cells, inactivating parasites and destroying pathogens and insects in food.
Science Daily April 16, 2008