May 2007
General field practices can reduce risk of contamination

Beginning in July, any supplier to a USDA food or snack program will be required to pass a Good Agricultural Practices (GAP) audit with a score of 80 percent or above. The audit verifies that growers are adhering to the best practices in FDA’s Guide to Minimize Microbial Food Safety Hazards for Fresh Fruits and Vegetables.

The first part of the audit is a general questions section, followed by four parts covering more specific areas that apply only if the grower is involved in those operations. They include an overall farm review, questions on field harvest and field packing operations, packinghouse facility and storage and transportation. Documentation of practices is required, and the necessary forms are included in the self-audit materials.

A self-audit is recommended, because it’s difficult to pass an official audit if the self-audit is not passed.

On-Farm GAPs

Some growers are concerned about the future implications of the audits, such as a question on the most recent audit that asks whether the farm is near a dairy farm. States with growing dairy industries are concerned that lawsuits could arise if land near a crop operation is rezoned allow cattle foraging putting a suspected transmission source, animal waste, closer to a human food source. But the goal of GAPs is to reduce the possibility of contaminated food products and increase quality of harvest and thus profitability.

Proper sanitation, temperature and moisture management greatly reduces the chances for post-harvest losses to bacterial soft rot and other decays, particularly in freshly harvested tubers,” said Jerry Bartz, post-harvest pathologist for the University of Florida.

Bartz’s research has shown that reducing moisture on freshly harvested potatoes and controlling the temperature can increase viability in storage. Processing potatoes harvested in late May and early June from Florida fields were stored at 86˚ F or 59˚ F for four days the maximum time from harvest and washing to arrival at the processing facility. The tubers stored at 86º F formed bacterial soft rot within one day, and by day three were not usable for processing. The tubers stored at the lower temperature were free of soft rot through the four-day test.

“The cooling process removed some of the surface moisture, slowed bacterial activities and, we think, kept the tuber tissues from becoming anaerobic, which is known to enable the rapid development of bacterial soft rot,” Bartz said.

GAPs also cover techniques and equipment that can increase the quality of the potato harvest. Cleaning harvesters and the containers used for transportation and storage can reduce not only soft rot but other harmful bacteria. Harvesting too quickly can damage tubers, and harvester depth can damage the skin and create an entry point for disease. Proper vine kill will ensure the skin set is sufficient to reduce the chance of post-harvest decay as well.

Water is a significant topic in GAPs, and growers should monitor their water sources for contamination. Water that is applied just prior to harvest should be potable, as should water used for washes after harvesting. But the most important practices, Bartz said, involve controlling the temperature and moisture.

“Absolutely avoid putting wet tubers into storage or allowing them to become wet with condensation or roof leaks,” he said.

Food Safety

The produce industry has to work as an integrated whole and commodity groups have to work together to protect their products, said Steve Ingham, a food safety Extension specialist with the University of Wisconsin, Madison.

“If one company goes down, the whole industry goes down,” he said.

The beef industry has been combating foodborne illness since a 1993 outbreak of E. coli O157:H7 in contaminated beef at Jack-in-the-Box restaurants in the Pacific Northwest. In response, the beef industry created a task force to find the knowns and unknowns of E. coli, and contamination has dropped nearly 80 percent since then. The industry’s response was “a mix of self-policing and regulatory nudges,” Ingham said, similar to what the produce industry is now seeing.

“One reason for the lack of interest in GAPs (for potato production) is the lack of foodborne illness in the product,” said Keith Schneider, assistant professor in the food safety and applied nutrition department at the University of Florida. “Since the product isn’t typically consumed raw, (it’s) not likely to have much of a health problem unless you get into unpreserved, pre-cooked or improperly cooled product with C. botulinum or B. cereus.”

Many retailers are concerned about the perceived risk to the food chain, and growers of all crops need to be aware of and follow GAPS, Ingham said.

“It’s pretty obvious that consumer groups are demanding something,” he said.

Growers producing potatoes for the fresh market and processing industries already are seeing more requirements from their customers, but so far there are no federal regulations.

“Are regulations coming? I don’t know,” Ingham said. “If there’s a perceived weakness in the industry, they may be coming.”

GAPs cover a range of production topics, from field preparation to worker hygiene to equipment sanitization. But Ingham said there is one overriding goal of field crop GAPs the avoidance of animal and human waste.

“Public enemy No. 1 is feces,” he said. “GAPs is a way of looking at risk reduction.”

The top three pathogens that sicken the most Americans in a year are E. coli, salmonella and hepatitis A, all of which are spread through fecal contamination. While there is the possibility that workers could spread pathogens by not practicing good hygiene, Ingham believes it is much more likely contamination would occur from animals or water.

He advises keeping all animals out of the fields, even domestic pets. Fences should be constructed to keep wild animals out, and sacrifice plantings could reduce the risk of contamination in areas prone to animal incursions.

Water sources and the quality of water should be closely scrutinized, and GAPs can help manage the risk areas involved with water. Testing the source of irrigation water is one practice, but Ingham said it’s difficult to test for the absence of something.

Learning From Leafy Greens

Regional guidelines like the California Leafy Greens Marketing Agreement may be a way for the industry to police itself, with support from a legislature. The marketing agreement was voluntary for producers, shippers and handlers to sign, but once they agreed the GAP metrics became binding (close to 100 percent of the leafy greens from California are produced under the guidelines). Leafy green producers pay an assessment, but they also can display a symbol on their packaging that shows they follow the scientific guidelines outlined in the agreement.

“California is a microcosm of what we might see,” Ingham said.

Meat and poultry have mandatory federal guidelines, but that might not make sense for produce because different areas have different production problems, and the wide variety of fruits and vegetables make it difficult to have specific guidelines.

“GAPs are general, and you need to apply (them) to your regional operation,” Ingham said.

FDA is undergoing a reorganization to be more efficient and faster at recognizing outbreaks. FDA Commissioner Andrew von Eschenbach said he favored guidances over regulation because they can quickly adjust as researchers learn more about contaminants like E. coli O157:H7. But if the produce industry does not make a concerted effort to police itself and increase food safety protocols, von Eschenbach won’t rule out regulating fruit and vegetable production which will directly affect potato growers who aren’t yet driven to conduct the audits.

“If FDA mandates GAPs, then I believe their interest will rise accordingly,” Schneider said.”

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