Minimum Processes, Maximum Hurdles

January 1, 2009
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Martin Cole, director of the National Center for Food Safety and Technology, and the 35-liter high pressure processing unit used to validate commercial sterility of low-acid, shelf-stable foods in an FDA filing.

Hey, good looking: presentation is almost everything, and interventions that preserve the appearance of fresh seafood are almost as important as those that combat unsafe microbes. Source: Vitiva.


Jenna Norwood is a raw-food missionary, drawing new acolytes each day to the gospel of minimally processed foods. Simultaneously, Jenna is increasing pressure on the food industry to minimize the potential dangers of a healthy diet.

There are scores of Jennas challenging their 20-something peers to go beyond vegan and organic diets and start consuming raw goods. Playing off the title of Morgan Spurlock’s “Super Size Me,” Norwood starred in the documentary “Supercharge Me,” her 30-day odyssey to a slimmer, trimmer figure and healthier, energized body through a diet of fresh fruits and vegetables. A YouTube collection of 40 raw lifestyle videos, some viewed more than 88,000 times, attest to the viral reach of the minimally processed message.

For a variety of reasons, young adults are rejecting the diets that defined previous generations. Beef as a symbol of economic wellbeing is old school: young Americans are putting fresh produce at the center of their plates. The dietary shift is paralleled by a disturbing trend in food safety failures. “Fresh produce is now the leading cause of foodborne illness,” notes Martin Cole, director of the National Center for Food Safety and Technology (NCFST) in Summit-Argo, IL. Viruses transmitted through food are a growing concern, he adds.

It would be a mistake to dismiss these new consumers as faddists and out of the mainstream. In fact, they reflect the contradictory desire for foods that are both convenient and fresh, packaged and full of nutrition. Their demand for food that is minimally treated and still safe to eat also poses a major challenge to manufacturers dedicated to serving a non-agrarian population.

Food recalls in 2008 were evenly split between produce and red meat, maintains Seattle attorney William Marler of MarlerClark LLP. The firm offers food-safety consultations to the industry, though its primary business is litigation. Beginning with the E. coli 0157:H7 outbreak at Jack in the Box in 1993, MarlerClark has collected more than $300 million in claims for its food-poisoning clients.

Most recently, Marler settled the last of three cases involving deaths linked to 0157:H7-infected spinach, 25 months after the September 2006 outbreak. In all, the firm represented 76 of the spinach victims. Defendants included Dole Food Co., the implicated brand; Natural Selection Foods, the processor and distributor; and Mission Organics, the grower. While terms of the settlements remain confidential, Marler previously pegged cases involving life-threatening symptoms at $1 million-$15.6 million per patient, while less-severe E. coli cases typically settle for $25,000-$500,000 each.

“The industry struggles with raw foods, especially leafy greens, because they are products without a kill step,” Marler points out. August’s decision by the US Food and Drug Administration to allow ionizing radiation in doses of up to 4 kilogray (kGy) on fresh iceberg lettuce and fresh spinach is a welcome change, he adds, but absent a definitive kill step, “you have to approach pathogens in a holistic way, beginning with what is going on at the farm.” Low-dose irradiation of 1 kGy can achieve a 3 log reduction in Salmonella in poultry and E. coli in ground beef.

The national spinach recall in 2006 was closely followed by food-pathogen illnesses at Taco Bell and Taco John fast-food restaurants. Lettuce and green onions were the suspected carriers, though no definitive cause was pinpointed. The cumulative effect was a leveling off in growth in a category that, up until then, enjoyed quarter after quarter of bullish growth. “A lot of recall incidents get forgotten,” says Teri Johnson, industry manager-fresh cut at Key Technology Inc., Walla Walla, WA. “People haven’t forgotten about those.”

Leafy green vegetables are conveyed into an optical sortation machine for inspection. Vision, laser and other technology is being brought to bear to improve the safety of minimally processed food. Source: Key Technology Inc.

Pay me now, pay me later

Because the spinach contamination was attributed to wastewater runoff, most likely from nearby cattle and hog operations, most of the minimally processed produce business has focused on farm-level practices to minimize risk. Virtually all California growers of leafy greens now participate in marketing agreements requiring food-safety audits conducted by state inspectors. Going beyond that is Natural Selection. Field practices, including testing of seeds for pathogens prior to planting, are part of the San Juan Bautista, CA, firm’s program, but the heart is extensive sampling in a test-and-hold approach.

The raw product test-and-hold program is based on standards developed by the beef industry, Executive Communications Director Julie Morris for Natural Selections’ Earthbound Farm brand told an October 2007 food safety symposium. Incoming produce is tested because microbial contamination usually occurs at the farm level, she said, but the company also pulls samples from finished goods prior to shipment.

The firm gathers 47 samples per pallet of incoming product, then holds the lot for 24 hours. If test results are negative, the raw materials are processed, bagged and put on another 24-hour hold for final testing before moving into distribution. Though expensive, it’s a lot cheaper than a recall, company officials say.

Fresh-cut margins used to be among the biggest in the processing industry, but that no longer is the case. Dole Fresh informed customers it would tack a 22-cent a carton surcharge to strawberries and vegetables to pay for safety enhancements beginning in April 2007, and Taylor Farms, a major producer in Salinas, CA, announced a similar assessment. But most growers lack the clout to make similar charges stick, and they are reluctant to adopt the kind of testing that Natural Selections does. “They’re trying to test their way out of it,” groused one source. Others are more supportive and point out beef processors resisted testing as well, despite of the important feedback it can provide “about who you are buying from, where the raw materials are coming from, and what was happening in your plant on a given day,” says Marler. Unfortunately, some prefer not to have a record of staffing shortages or out-of-spec processing parameters, he says.

While applauding Natural Selection’s efforts to prevent future incidents, Marler singles out Fresh Express for being “out front in trying to deal with food safety.” A subsidiary of Chiquita Brands, Fresh Express dispensed $2 million in 2007 to fund nine research initiatives to determine how lettuce and spinach become contaminated and to suggest strategies and technologies to mitigate risk. On September 11, Fresh Express publicly reported the results of those projects.

Researcher Jorge A. Giron and colleagues from the University of Arizona evaluated chlorine, ozonated water and peroxyacetic acid-based antimicrobials added to flumes and wash water to kill bacteria in the stomata, or pores, of leafy greens. Even with chlorine concentrations of 1%, “viable bacteria were recovered after treatment,” they report. “Treatment with ozonated water kills 99.9998% of the bacteria, while Tsunami treatment does not eradicate all the internalized bacteria.” Tsunami is Ecolab Inc.’s trade name for a peroxyacetic acid solution.

The highest lefts of pathogenic cross-contamination of iceberg lettuce and baby spinach occurs in the flume water, at mechanical shredders and on conveyor belts, a team from Michigan State University concluded in another Fresh Express-sponsored study. Those researchers are developing a predictive model of bacterial transfer during processing. “These findings,” they wrote, “along with the probabilistic risk assessment model being developed, reinforce the importance for proper cleaning, sanitizing and maintenance of the equipment.” But that conclusion ignores the possibility of airborne contamination. (See related story on page 96.)

A fundamental shift in risk management is occurring, NCFST’s Cole observes, with food safety objectives and performance objectives serving as starting points. The idea is to determine an acceptable threshold for the safety of food at the time of consumption, then work backward through distribution, processing and raw-material handling to set multiple hurdles and their ability to minimize and reduce the levels of risk to achieve the objective. “There’s not one risk management option that is going to get you there,” says Cole. Field practices, washing regimens, cold-chain maintenance and interventions such as chemical treatment and high-powered ultrasound can be part of the mix for minimally processed vegetables.

Cole is one of four US representatives on the International Commission on Microbiological Specifications for Foods. The commission’s food safety objectives (FSO) and performance objectives (PO) tools build on HACCP and GMP to achieve public health objectives. “Assessing processing and preservation parameters is the preferred option to check that an FSO or a PO is met,” the commission maintains, “but sometimes sampling and testing against a microbiological criterion can be used.”

Pathogens are not the only foreign materials of interest, and the sheer volume of product running through a high-performance plant reduces the likelihood that sampling will flag a problem. In the fresh-cut category, 5,000 to 20,000 lbs of product an hour is common. Just as beef processors monitor spoilage organisms that are precursors of more serious problems, fresh-cut processors are beginning to capture, store and analyze data on foreign materials flagged by optical sorters.

A module called FMAlert that works with G6 optical sorters recently debuted from Key Technology. The digital-image storage unit emulates similar devices used in pharmaceuticals, where every disruption has to be validated. Glass, metal, cardboard, fecal contamination-all can signal a larger problem. Simply removing the object doesn’t address the potential problem, points out Key’s Johnson. “When foreign materials are found, processors need to shut the line down and do an assessment to see if the product can be cleaned or needs to be thrown out,” she says.

Electronic noses and other technology soon may join the fluorescence-sensing lasers, visible-infrared cameras and other electro-optical tools mounted on the top and bottom of sorters such as Key’s Manta, a 2 meter-wide machine. “Laser technology itself hasn’t changed much,” says Johnson. “What has changed is the ability to keep the laser and camera clean and operating in wet, cold environments.”

 The ability to fluoresce chlorophyll that should be present and to analyze the shape and size of objects that shouldn’t is helping drive productivity improvements without compromising safety. Still, the challenges of raw produce are multiple. Thrips, a translucent insect also known as corn lice and measuring less than an eighth of an inch long, defies detection, yet its presence also suggests the presence of fecal matter. Identifying those types of contaminants may be more important than simply removing them.

Photolytic systems such as electron pasteurization will get a foothold in fresh cut, predicts Key’s Richard J. Hebel, chief technology officer, “but I don’t know if the public will ever get its head around safer food that has been irradiated.” Skepticism goes beyond misunderstandings about the technology itself and extends to a fear that low-level radiation would be a crutch that promotes laxness. Multiple hurdles beginning with best practices in agriculture to in-plant inspection and remediation are essential, he says.

Martin Cole, director of the National Center for Food Safety and Technology, and the 35-liter high pressure processing unit used to validate commercial sterility of low-acid, shelf-stable foods in an FDA filing.

New hope for high-pressure

Use of high-pressure processing is steadily expanding, thanks in large part to the commercial work of Fresherized Foods (see “Fabulous Food Plant,” Food Engineering, October 2008), but scientists were stymied in demonstrating the technology’s ability to deliver shelf-stable foods that were minimally processed to safeguard their nutritional value. The resistance of spore-forming bacteria to destruction by pressure alone frustrated researchers in the Dual Use for Science and Technology (DUST) program, a collaboration between the Department of Defense, food companies and research scientists.

Last fall, DUST collaborators used thermal-processing guidelines for low-acid canned foods in a filing with the FDA. They dubbed the process pressure assisted thermal sterilization (PATS). Using a 35-liter press from Avure Technologies Inc. at NCFST’s labs, scientists preheated the food and allowed the pressure to elevate temperature to 120° C. While heat-sensitive vitamins and other nutrients are unlikely to survive, the pressure significantly accelerated processing time. Set-point temperatures were reached in 2.5 minutes, compared to a half an hour in a conventional retort (see chart). Hold time was only a minute, and product cooled in 4 seconds after pressure was released.

PATS gives FDA process authorities a familiar framework to work with while delivering the microbial reduction required. Calling the 12-log standard for sterilization “anecdotal,” NCFST’s Cole says it unnecessarily complicated the validation of high pressure. “It’s nonsense,” he scoffs.

International experts are nudging the global food-safety community away from arbitrary standards and trying to look at the cumulative effect of multiple tools to meet people’s desire for food that is healthy, minimally processed and convenient. Thermal destruction of all life forms is neither necessary nor compatible with those objectives. Cole points to grandfathered products like Spam that take advantage of multiple hurdles to arrest growth of life forms that might survive initial treatment.

Processors increasingly are turning to protections found in nature to safeguard minimally processed foods. Morristown, NJ-based PL Thomas & Co. Inc. lists more than 40 extracts from fruit, vegetables and spices that it supplies to companies that wish to present a clean label for their raw and minimally processed products. “There are certain market channels (retailers) where it has become absolutely essential that the label does not include BHT, TBHQ or other chemical preservatives,” according to company President Paul Flowerman. So-called botanicals that arrest rancidity and oxidation and provide some antimicrobial protection are becoming mainstream replacements. His firm taps a global network of ingredient developers like Vitiva, a Slovenian company with a staff of research scientists focused on rosemary extracts.

 Also known as INOLENS, the newest rosemary extracts are tasteless, odorless and colorless. This neutrality allows significantly higher dosages on uncooked salmon and other proteins, protecting against rancidity by a factor of four. Natural preservatives for raw foods are “absolutely mainstream” now, Flowerman emphasizes. “The largest food companies are on the natural-food bandwagon.”

Color, odor and texture changes may not compromise the safety of fresh foods, but they cost processors untold millions. An estimated 15% of beef at retail is returned or sold at a discount because of color changes.

More tools for safeguarding minimally processed foods are on the horizon, and, like the DUST program, they come courtesy of DOD. DUST was driven by a desire to deliver more flavorful and nutritious field rations to soldiers. The slow progress of high pressure helped provoke a new initiative called Detect to Protect. The idea is that fast-moving military units sometimes must graze on locally available food. To reduce the risk that contaminated products could knock soldiers out of commission, the Army Sensor Command has overseen the development of technologies that eventually will benefit commercial food production. They won’t replace current technologies and best practices, but they will present new hurdles to food-borne illness.

For more information:
Glenn Hewson, Avure Technologies Inc., 253-981-6239, glenn.hewson@avure.com
Teri Johnson, Key Technology Inc., 509-394-3358, tjohnson@key.net
Richard J. Hebel, Key Technology Inc., 509-394-3394, rhebel@key.net
John J. Hayman Jr., KES Science & Technology, 770-427-3766
William Marler, MarlerClark LLP, 866-770-2032
Paul Flowerman, PL Thomas & Co., 973-984-0900, rodger@plthomas.com

A technician installs a photocatalytic oxidation unit on the wall of a cooler in a fresh-cut vegetable facility. The unit purifies air of bacteria, viruses and other organisms to minimize the spread of airborne contaminants. Source: KES Science and Technology Inc.

Air defense systems

Safety specialists who focus on food-contact surfaces as the medium for cross-contamination often ignore the likelihood that airborne microorganisms are compromising their products, insists John J. Hayman Jr., chairman of Atlanta-based KES Science and Technology Inc.

Mycotoxins, spores, viruses and bacteria don’t need a conveyor belt or cutting surface to infect otherwise clean foods. “The air is what cross contaminates from one product to the next, when food is shifted from one area to another,” says Hayman.  The advent of HVAC systems and buttoned-down buildings has aggravated the problem, he adds, and HEPA filters are incapable of lowering risk to an acceptable level. Nine years ago, KES licensed an air system based on titanium dioxide excited by a UV lamp in a photocatalytic oxidizer to mineralize VOCs and destroy microorganisms. The technology was developed at the University of Wisconsin on behalf of NASA, which needed a way to remove ethylene gas respirated by wheat grown in space.

Each unit outputs 20 cubic feet of purified air a minute. The number of units deployed depends on the amount of air that needs to be purified, based on air-quality monitoring.

KES has supplied misting systems and other food-safety aids to grocery stores, distributors and others for more than 30 years. Hayman describes the Airocide PPT (perishable protection technology) as his “pet project.” Wineries and yogurt manufacturers are among the technology’s early adopters, though he admits penetration in produce processing and other segments has been slow. Nonetheless, he predicts airborne contamination eventually will be recognized as a prime threat. “There are very few flagellating bacteria,” he points out. “Once processors understand the practicality of what PPT does, it will become the standard.”

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