Harmless bacteria can be used to fight illness-causing pathogens that form on fresh cut fruit, according to the results of scientific tests published this week.
Microbes can form on the surface of a peel or rind and transfer to the flesh of fruit when cut with a knife and the natural protection barrier is broken.
Most fresh cut fruit is sold in ready-to-eat formats, and with consumers unlikely to wash produce prior to consumption, processors are looking for ways combat this inevitable contamination.
Agricultural Research Service (ARS) scientists were part of a group of researching ways to control Listeria monocytogenes on honey dew melon pieces during exposure tests.
L. monocytogenes are food borne bacteria that multiply at low temperatures and survive refrigeration. Fewer than 1,000 organisms can cause sickness to humans, sometimes leading to more serious illness.
The scientists artificially contaminated the melon that had been treated with three different solutions.
Gluconobacter asaii, a non-toxic bacteria that is naturally present on the surface of pome fruits, such as apples and pears, was applied to some melon during testing.
Other samples were treated with a mixture of six bacteriophages, viruses that attack bacterial pathogens but are non-toxic to humans.
The third test combined the bacteriophages with G. asaii and was the most effective of all, reducing L. monicytogenes populations by 99.999 per cent, claims ARS.
According to ARS scientists, bacteriophages had an immediate inhibitory effect, while G. asaii's offered longer term control.
G. asaii is effective because it competes for space and nutrients on the fruit surfaces where the bacteria would otherwise exist. The bacteriophages invade bacteria and damage walls, which allow more to invade to cause further damage.
The findings follow regulatory guidance issued by the Food and Drug Administration (FDA) last week that advised fresh cut processors should immediately implement safety standards to prevent product contamination.
The advisory was issued in the wake of outbreaks of foodborne diseases from spinach and lettuce.
The FDA called on processors to implement the Hazard Analysis and Critical Control Points (HACCP) system throughout their supply chains.
The international safety standard is designed to prevent, eliminate, or reduce to acceptable levels the microbial, chemical, and physical hazards associated with food production.
The guidance is meant as a complement to the FDA's Current Good Manufacturing Practice regulations for food.
Specifically, it deals with the production and harvesting of fresh produce and provides recommendations for fresh-cut processing, including procedures relating to personnel health and hygiene, training, building and equipment, and sanitation operations.
It also deals with fresh-cut produce production and processing controls from product specification to packaging, storage and transport.
The guide also provides recommendations on recordkeeping and on recalls and tracebacks.