To deal with potential contamination by E. coli and other pathogens, growers and handlers of all perishable produce need to adopt a “top-down” commitment by management personnel to food quality and safety, according to Trevor Suslow, University of California, Davis specialist in postharvest pathology.
“Recent outbreaks across the produce industry,” he said, “have really caused major changes in attitudes and approaches to the safety of all perishable produce. You should take the opportunity to be proactive with planning, coordination and communication.”
Suslow gave that advice recently at an educational symposium held in Fresno by the California Tree Fruit Agreement as he reported on his research in peaches, plums and nectarines.
As scientists evaluate recent research data and gather more specifics, he has developed, through interaction with growers and shippers, a “quick start self-audit” group of Good Agricultural Practices (GAPS) as a general guide for establishing programs to ensure food safety.
Noting that the goal of all food safety programs is zero illness, he said the approach is to identify potential hazards and prevent them from occurring. While a few practices are known to be safe and many more are known to be unsafe, a vast, uncertain, “gray” area lies between.
Until more information is developed, it is vital that farming operations maintain detailed records of the GAPS they are following. GAPS, he said, can build awareness, but more importantly, they are invaluable in verifying procedures and tracing any concerns or problems back to their true source.
The sections of the GAPS guide include documentation (farm history and cropping), employee training, fertilizers, water quality, field sanitation, worker hygiene, and pest control.
Owners and senior production managers can use the guide to assign priorities and chart progress in moving toward fulfillment of goals. Guides, in printed form or on CD, are available through http://ucgaps.ucdavis.edu.
Suslow pointed out that data is being compiled for growers to use in tailoring programs suited to individual operations and particular crops.
For instance, in an orchard situation more than 100 feet from a dairy or other source, the number of E. coli can drop off dramatically to extremely low numbers. Yet research on lettuce shows that significant numbers of the pathogen can reach the crop 400 feet from a source.
In his research on sanitizing agents for peaches, plums, and nectarines, he learned that washing fruit in water treated with chlorine and lactic acid appears to be effective in reducing pathogens, although additional tests with mechanical brushing of fruit are needed and are planned for this year.
Small doses of lactic acid were used, he explained, because of reports of success with it in killing bacteria in the meat industry and the tomato industry.
He also investigated exposure of fruit to slow-released chlorine dioxide gas, shown to perform well with several fruits and vegetables. His experiments found it to be extremely effective in reducing Salmonella and E. coli O157H7 on peaches and plums, but more testing will be needed for nectarines.
Another potential means of delivering chlorine dioxide gas could be through newly developed films that release the gas when activated either by light or by moisture.
The food safety segment of the symposium also featured a talk by Will Daniels, vice president for quality food safety and organic integrity at Earthbound Farms in San Juan Bautista, Calif.
Earthbound, the nation's largest grower, packer, and shipper of organic produce, is the manufacturer of the spinach salad that caused the outbreak of E. coli in August of 2006. Daniels said he hoped his remarks would help others avoid the ordeal of having contaminated produce recalled.
Even though the company operated without a contamination incident for the 22 years prior, the problem did occur and it prompted them to mount a more intensive program.
Daniels said it must be recognized that pathogens exist in the environment and raw materials are where a hazard is likely to originate. It is vital for producers and processors “to test to detect so we can prevent, especially for fresh-cut, ready-to-eat products.”
And, he added, it is extremely important to develop uniform, national standards that make sense for consumers and the industry.
“There is a lot of pressure from industry, retailers, and consumers to deliver a safe product, and they deserve a safe product. But there is no guarantee for the produce industry without a ‘kill step’ involved, certainly not in the organic industry,” Daniels said.
Even with special efforts for unified standards by the leafy greens industry, the metrics involved thus far are “not based on pure science but mainly on “good guesses.”
Earthbound's GAPS-guided, pathogen testing program ranges from seed, water, soil amendments, and plant analysis to postharvest, with multiple practices and tests, or “hurdles,” to thoroughly inspect produce at all stages of production.
Its adoption of mechanical harvesting of greens in 2001 called for special laser equipment to detect foreign materials. Although washers with disinfectants now remove massive amounts of microbial contaminants, new designs and sanitizing methods with effectiveness nearing pasteurization are on the horizon.
Although it monitors for wildlife in fields, Daniels said the operation does not anticipate fencing farmland or growing in greenhouses.
Since most microbial contamination of agricultural commodities most commonly occurs at the farm level, Daniels said, the environment presents challenges to total control. Their program is based on standards developed by the International Commission on Microbiological Specifications for Food.
“A test and hold ‘firewall’ reduces the risk of contaminated raw materials entering the processing environment.”
Although they have always practiced sanitation, Earthbound has also increased its field auditing staff for unannounced inspections of all ranches and harvest crews. “The paradigm has changed from ‘let's get ready for an inspection’ to ‘let's be ready for an inspection every day,’” Daniels said.
They are working toward a unified standard for unannounced third-party audits, by commodity and by industry. Their GAPS efficiency is monitored through statistical process control (trending and tracking) of test data, in-house monitoring audits, and third-party verification audits.
“As a final safeguard, finished goods testing is a secondary ‘firewall’ to verify the efficacy of our upstream interventions,” Daniels said. All salads are lab-tested and held until results return negative for pathogens. Only then is the product released for shipping.
Earthbound is also involved with other vegetables, tree fruit, and grapes, and sees the need for commodity-specific guidance documents.
In other presentations at the symposium, Kelvin Farris of Aweta-Autoline, Reedley, discussed new sorting equipment that uses acoustics to measure fruit firmness. Kelly Kirschner of Sinclair Systems International, Fresno, described tiny individual fruit labels with bar coding which allow tracing for identification of packinghouse, sales, inventory, and other purposes by retailers.