FOCUS: PRODUCE SAFETY
By Elena Castell-Perez, Ph.D. and Rosana G. Moreira, Ph.D.
An Engineering Approach to
Ensuring the Safety of
Fresh and Fresh-cut
Fruits and Vegetables
Consumers are becoming more aware of the importance of eating fresh and fresh-cut fruits and vegetables. How-
ever, these minimally processed foods
have repeatedly become a source of
foodborne illnesses in the United States.
Escherichia coli O157:H7, Salmonella spp. and Listeria spp. are a
public health concern, since these microorganisms have been asso-
ciated with foodborne outbreaks from consumption of cantaloupes,
sprouts, spinach, lettuce and bagged salad mixes.
Recent studies indicate that pathogenic microorganisms may internalize into
the core of leafy vegetables rather than contaminate the exposed surface only. This
bacterial mobility makes surface treatments to reduce pathogens very ineffective.
Most of the commercially used interventions employ chemical agents, such as
washing with 2% chlorinated water, which cannot either wash these pathogens off
the produce or inactivate them. Another side effect of this treatment is detrimental
effects on the organoleptic properties of the food.
Since current production and processing practices cannot ensure pathogen-free
fresh and fresh-cut produce and with almost 25% of food production after harvest
in the United States lost due to damage caused by bacteria, mold, insects and contamination with spoilage microorganisms, effective food safety interventions are
needed for implementation throughout the production, processing and distribution of these food items. Development of alternative pathogen decontamination
technologies would certainly improve the safety of ready-to-eat and fresh agricultural products.
Because thermal processing of fresh produce is not an option, non-thermal in-
terventions are the only means to include as a lethality step in processing and han-
dling of fresh fruits and vegetables. Technologies include high-pressure processing,
radio frequency, pulsed-electric fields,
ultrasound, irradiation and others. Treat-
ment of fresh produce using ionizing ra-
diation has a significant strategic
importance for the future of food safety
worldwide. This is simply because it is
the most researched non-thermal food
process technology and has been proven
that it is safe (when done properly). Yet,
despite the impressive advances in irradi-
ation methods available, the technology
must still be optimized for application
to all types of fresh and/or minimally
processed fruits and vegetables.
Food irradiation is the exposure of
the food, either packaged or in bulk, to
controlled amounts of ionizing radiation for a specific time to achieve a specific amount of inactivation of
pathogens. The word “controlled” is
very important because the irradiation
treatment requires rigorous process control to ensure that the dose delivered to