Can Cantaloupe Be Made Fit For Purpose?
Article by By Eric Wilhelmsen, Ph.D., CFS Published November 5, 2024
Article Source: Can Cantaloupe Be Made Fit For Purpose? | Food Safety
As a premise for this discussion, given that there are outbreaks and illnesses associated with cantaloupe or netted melons, not all melons are fit for purpose. Given that the peel is not consumed, there is either cross-contamination or internal contamination that causes illness. Zero risk is impossible, but can industry do better?
For many products and commodities, there are alternative channels of distribution where product with a higher risk profile can be directed. This often involves cooking or pasteurization to address the potential for higher pathogen loads. These redirections happen because some lots of product are deemed unfit for some purpose, and so they come at a cost. Rephrasing the title question, can the cantaloupe marketplace be stratified to redirect product to reduce illness?
For cantaloupe, the primary microbial hazards are Salmonella and Listeria. It is not unreasonable to expect pathogenic E. coli to also be a hazard. These hazards present through three mechanisms:
Surface contamination due to water, soil, or soil amendments
Systemic contamination by root or blossom (physical damage can also occur, allowing internalization of surface contamination)
Contamination or cross-contamination during handling.
Surface contamination is expected to be the major source of illness and is the most easily addressed mechanism. Systemic contamination will need to be addressed by GAP (Good Agricultural Practices) programs. Verifying control of surface contamination will potentially mitigate systemic internalization, which appears to require high levels of contamination. The dose–response curve has not been characterized. A combination of GAP, GMP (Good Manufacturing Practices), and sanitation procedures are needed to control contamination during handling. Treating melons as food as soon as possible—even though they will be peeled—is needed to mitigate the risks associated with these three mechanisms.
Mitigation and verification of these controls will generally add costs in a low-margin commodity business. The measures necessary to control these three mechanisms are well known, but are executed with varying degrees of success. Outbreak investigations of melon typically cite failures in these control measures. Verification of these control measures can be achieved through testing and method or process validation. New science is not needed. The challenges are achieving complete compliance and getting the costs for these efforts covered. No one wants to accept a price increase, and no one wants to add a new expense. Unilaterally implementing new controls could put a stakeholder at a disadvantage in a commodity market. The fresh-cut sector of the produce business, where brands are highly visible, may be able to take advantage of improvements if customers determine that the added safety is valuable.
Compliance is an ongoing problem for food safety. The food industry speaks of food safety culture, training requirements, and systems for developing preventive measures. For the sake of brevity, I will table these aspects of the problem for others to address.
The impasse to cover the costs for food safety-related changes can be broken in several ways. Regulations can require mitigations to be implemented, or they can require performance verification that penalizes noncompliance. Aflatoxin standards for food products is an example of the latter. Industry and trade associations can come together to create standards that become accepted best practice. The Leafy Greens Marketing Association (LGMA) is an example of this process. For cantaloupe, the current effort to convene a working group to revise the 2013 standard for cantaloupe production by the Western Growers Association (WGA) may yield some improvements; the first meeting of the working group was held on April 23 of this year. A third way that this impasse can be broken is for a stakeholder to achieve a technical breakthrough so disruptive that all other stakeholders must adapt to stay in business. For a food safety change, the breakthrough needs to be accepted and recognized as a benefit by customers and/or consumers.
Having consulted for multiple stakeholders in this category, I hope for several changes that will help stratify the cantaloupe marketplace or ensure that more melons are fit for purpose:
A practical microbial standard is needed for whole melons
An effective process is needed for safely producing fresh-cut cantaloupe
A strategy is needed to address melons that require special handling.
A microbial standard does not necessarily mean testing. The producer only needs to convince the customer that they should comply with the standard. It is probable that some level of testing is the easiest way to establish a level of performance. The U.S. Food and Drug Administration's (FDA's) regulatory standard method of analysis of whole melons is based on a pooled sample from thirty individually enriched melons.1 This method is expected to be hypersensitive and is not practical for routine assessment of GAP programs. A cloth-based aggregated sample from 5–10 melons would be a practical preharvest sampling approach. Cloth-based aggregated sampling is well established for protein foods.2
A presence/absence test based on one or more cloth-based aggregated samples should assess GAP performance and prevent high levels of contamination from reaching consumers. Unpublished research predicts a sensitivity of approximately 10 CFU/melon. The California Cantaloupe Advisory Board, in its 2004 Overview of Industry Practices, indicates that cross-contamination during cutting is measurable at about 340 CFU/melon. Given that melons are grown in soil, zero cross-contamination is not realistic.
Regarding safety when the standard is not met, the ideal level of control or mitigation is probably a 4–5 log reduction in pathogen load, similar to the goals for juice processing. Net-coated melons are notably difficult to process with traditional oxidizing sanitizers. Peeling, either by hand or machine, provides an approximate 2 log reduction.3 The more care taken in peeling, the better the reduction. Peeling reduces half of the desired lethality if cross-contamination from the peel is moderately controlled. If the load is known to be lower than a threshold such as that discussed above, then the peeling process is often enough to provide wholesome, fresh-cut melon for direct use or for use in a hygienic, fresh-cut operation. A fresh-cut operation for a high-visibility brand may only want to accept melons below the threshold and still use an effective wash process.
A 2-log washing process applied prior to shipment to consumers, or as part of a fresh-cut operation, would make up the difference to achieve a 4–5 log reduction in pathogen load. This treatment presents a conceptual alternative for melons that do not meet the standard that is being suggested. Such a process will not license gross failures in growing practices, such as using unfit water for irrigation, but it does appear to provide a way to stratify the marketplace and redirect melons when moderate contamination has occurred, or has potentially occurred. The cost of testing versus processing and the value of the involved brands will dictate how the marketplace works. Such a marketplace will only function if the cost impasse is broken.
However, this discussion regarding redirection is moot in the U.S. Without an identified kill step, any lot that tests positive for a pathogen will be deemed adulterated and unfit for food use. A conundrum still exists regarding the disposal of melons that have tested positive for a pathogen. I do not see a path to cover the costs of uniformly safer melons if the marketplace is primarily cost-based. At best, I can conclude that melons might be made fit for purpose.
In the interim, I will continue to enjoy cantaloupe—but I will handle whole melons like I do raw chicken, or purchase fresh-cut melon with safety assurances to avoid bringing contamination into my kitchen.
References
U.S. Food and Drug Administration (FDA), Office of Regulatory Affairs, Office of Regulatory Science. "ORA Lab Manual Vol. III Section 7—Private Laboratory Analytical Packages." Document Number MAN-000051. Revised December 8, 2023. https://www.fda.gov/media/73540/download.
Wilhelmsen, E. "Ongoing Improvements to Meat and Poultry Safety." Food Safety Magazine. October 11, 2022. https://www.food-safety.com/articles/8047-ongoing-improvements-to-meat-and-poultry-safety.
Wilhelmsen, E. Unpublished research.