Fresh-Cut Produce Presents Unique Food Safety Challenges

By Laurel Maloy, contributing writer, Food Online

Consumers are seeking new ways to improve their eating habits. Among them are Ready-to-Eat produce and meals. But with this comes a new, distinct set of safety and contamination concerns for its processors and packagers

Produce is playing center stage in homes around the world. The demand for it has gone up, as the focus on healthy living and eating has come to the forefront. Obesity, nearing epidemic levels in the U.S., drives a market clamoring for more, in terms of both variety and convenience.  This has resulted in produce shelves laden not only with fresh, whole fruits and vegetables, but with pre-packaged, sliced and diced, ready-to-eat (RTE) offerings. The packages are pretty, look fantastically appetizing, and actually make eating fruits and vegetables almost effortless.

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However, what many are not taking into consideration is the opportunity for microbial contamination and cross-contamination existing from the simple, yet time-consuming functions associated with preparing RTE produce. Produce, in and of itself, is highly prone to microbial contamination from field workers, infected soil, irrigation water, insects, and animal feces.

The CDC recommends washing hands, surfaces, and utensils repeatedly during the preparation process, even if you plan to peel them. The reason? Anything on the outside of the produce can be transferred to the inside, simply with the slice of a knife. Take, for example, the listeria outbreak from Jensen Farms. The Colorado producer produced and distributed cantaloupes resulting in a multi-state outbreak of listeriosis. These cantaloupes were whole, but 147 people in 28 states became infected with a death toll of 33. The infections occurred as a result of the fruit not being washed prior to slicing, causing the transfer of this deadly pathogen to the meat of the fruit. 

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The opportunity for contamination from RTE produce is even higher than the Jensen Farms incident. At every step in the process of creating RTE produce there is the possibility for contamination:

• In the field
• In the truck while being transported
• During dump-tank washing
• While slicing, dicing, or shredding
• On the conveyor belt
• While being sorted
• While being packaged
• When on display in the retail environment
• During home preparation

Experts will admit that some level of cross-contamination is impossible to avoid. Any time you have contact between the product, blades, and other contact surfaces of the machinery, cross-contamination can occur. A Michigan State University (MSU) study utilized 20 pounds of radicchio infected with E. coli O157:H7 in order to track the extent of contamination. E. coli naturally inhabits the intestines of all animals, even humans. Fruits and vegetables are commonly contaminated with it through irrigation water.

The color of the radicchio made it easy to track once the tainted produce was added to 2,000 pounds of iceberg lettuce during processing — shredding, conveying, washing, shaking to remove water, and then centrifugally drying. The infected radicchio continued to spread throughout the system, long after being introduced at the front end of the process.  Shredded lettuce is utilized as a control due to the difficulty of washing it at home and the high rate of foodborne illness infection attributed to leafy vegetables. MSU’s goal is to improve the process. They are doing so with the only pilot plant-scale processing line for leafy greens in the country. This gives MSU an edge, but also speaks to the need for further research and funding.

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Between 1998 and 2008 the CDC attributed 22.3 percent of foodborne illnesses to leafy vegetables. Fruits and nuts were third on the list at 11.7 percent, coming in just ahead of poultry at 9.8 percent. Vine fruits and vegetables followed poultry on the list, being responsible for 7.9 percent of foodborne illnesses. Grains/beans and root vegetables came in at rankings 9 and 10 on the list, with 4.5 percent and 3.6 percent, respectively.

Slicing presents even more challenges. Shredding is pretty much accomplished the same way across the industry, but slicing is done manually, semi-manually, or is accomplished with automated slicers. Most fruits and vegetables are washed in a sanitizing solution prior to slicing, though this is not considered 100 percent effective. MSU estimates only 90 to 99 percent of pathogens are exterminated during a sanitizing wash. Add to that the fact the slicers and/or knives will not normally be cleaned until the end of the processing cycle, and it is easy to see where cross-contamination can occur. In labor-intensive human slicing lines, the opportunity for contamination is even greater. Numerous studies have been done regarding the cross-contamination and transmission of Norovirus (NoV) through various slicing operations.

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Every step in the process presents an opportunity for improvement. Sanitizer washing needs to be more adequately monitored in order to reduce the organic load in flume water. One expert recommends washing shredded product near the end of the production cycle in order to reduce microbial cross-contamination. Packaging strategies vary with a host of scenarios needed so as to keep fresh-cut produce at its best and contamination free. Improved packaging methods are always being studied, but many are cost-prohibitive. Transportation of produce is being addressed by FSMA.

However, the logistics of produce handling is mind-boggling. How do you maintain constant temperature while loading and unloading in summer heat, setting up retail displays, and during the various stages of retail storage? How do you even begin to train the workforce from receiver to driver?

The demand for RTE produce is expected to continue to rise, and with it the opportunity for widespread, multi-state, foodborne illness outbreaks. Industry must look to the continued improvements in Good Manufacturing Practices (GMP) and Good Agricultural Practices (GAP). The FDA push for modernizing food safety standards has led to FSMA and the Standards for the Growing, Harvesting, Packing, and Holding of Produce for Human Consumption. All of these resources provide industry with the guidelines and tools necessary to accomplish what may seem like an impossible task — the burden of providing the consumer with safe, palatable fruits and vegetables.