Keeping Ready-To-Eat Foods Safe

May 12, 2015
From deli meats and hot dogs to fresh-cut produce and dips, ready-to-eat foods merit special interventions.

Ready-to-eat meat and poultry products pose the highest potential dangers but also represent the most impressive advancements in product safety in today’s food industry.

Even when multi-million-pound recalls of fresh ground beef were occurring with alarming regularity, regulators were targeting RTE proteins for special attention. Pathogenic E. coli frightened the public, but food safety experts knew that relatively mild thermal treatment was enough to neutralize these microbial wimps.

Listeria monocytogenes, on the other hand, is far and away the most lethal foodborne pathogen, and RTE products are a common infection avenue. A 2003 study published by the National Food Processors Association (a forerunner to Grocery Manufacturers Association) found Listeria in up to 4.7 percent of product samples, a finding made more alarming by sometimes-high cell counts.

USDA’s Food Safety and Inspection Service at the same time was forging the risk-based program for RTE protein foods that became effective in May 2006. If only sanitation protocols are used to minimize the risk of contamination in post-lethality product handling, Alternative III status is assigned, resulting in closer inspection and oversight from FSIS. Alternative II status is conferred if either a post-lethality treatment to reduce bacterial load (bactericidal) or a microbial suppression (bacteriostatic) step is applied. If both steps are applied, a processor is classified as Alternative I and is subject to the least regulatory oversight.

Immersing or spraying meat and poultry with hot water is the conventional post-cook treatment for deli logs, hams and other RTE products. Often referred to as ultra pasteurization, it’s a relatively inexpensive process but ineffective when product overlaps and can result in organoleptic deterioration. FSIS offers ultra-violet radiation as an option, although applications are limited.

Modified atmosphere packaging can have a bacteriostatic or bactericidal effect, particularly when carbon dioxide’s antimicrobial properties are part of the gas mix, and it is effective with sliced meats. But MAP costs are double those of vacuum packaging, and the gas has a bacteriostatic, or suppressant, effect, Both bacteriostatic and bactericidal interventions are necessary to secure Alternative I status, and two methods to help achieve it for sliced meats are emerging: an antimicrobial spray at the slicer and high-pressure processing.

Spraying a deli log is fairly straightforward, assuming chemical temperature and dispersal rates are monitored and recorded for efficacy. Spraying sliced meats requires integration of one vendor’s slicing machine with a spray system from another supplier.

A high-speed camera was used to validate a chemical-spray system’s ability to completely coat individual pieces of meat as they fell from a slicer during tests at Lower Foods. Photo: Sono-Tek Corp.

Is that a challenge? “You can say that again,” deadpans Joseph Riemer, vice president-food business development at Sono-Tek Corp., Milton, N.Y. Nonetheless, the spray nozzle manufacturer has integrated its ultra-sonic system with multiple slicer-manufacturers’ machines and has four systems in commercial production. One is in a meat plant in Spain; the other three found a home in the Richmond, Utah, base of Lower Foods Inc.

“We’re pretty excited about it,” enthuses president Alan Lower, whose firm has sprayed antimicrobial agents in whole-muscle bags “for years and years.” When technology for sliced deli meat became available, Lower Foods didn’t hesitate. Sono-Tek’s first system was incorporated with a Titan slicer on a new line in the fall, with two additional installations following.

“The Sono people are perfectionists,” adds Lower. “It hasn’t skipped a beat.”

In validation tests performed in October, sufficient log reduction to demonstrate effectiveness was achieved using lauric arginate (LAE) from A&B ingredients. Concentrations were above the 50 ppm threshold to qualify as a processing aid. Lower Foods is trying to establish efficacy at 44 ppm, which would exempt products from listing LAE on labels.

FSIS permits two dozen antimicrobials in direct contact with RTE foods, half of which can be considered processing aids that do not require label disclosure. Precise dosing and coverage are necessary for effectiveness, and that’s impossible to achieve with air nozzles, according to Riemer. With ultra-sonic spraying, 50,000 electronic signals per second cause the nozzle tip to vibrate, eliminating pressure from the equation and resulting in tighter uniformity in droplet size. The result is consistent dosing of up to 1,000 slices per minute.

A similar sliced-meat system from Spraying Systems Co. debuted early last year, complementing the Wheaton, Ill., firm’s decade-old RTE interventions for whole meats, according to Josh DeVoll, director-market solutions. The company provided input to FSIS when the risk-assessment hierarchy was being developed, he adds, which is why its SLIC (Sprayed Lethality in Container) line predates the 2006 final rule.

Before the sliced-meat system was developed, Spraying Systems enjoyed success with whole muscle and other bagged RTE meats. An antimicrobial spritz could be introduced either into a preformed bag or on rollstock prior to bag forming. When a vacuum is pulled prior to sealing, the antimicrobial agent is evenly distributed, providing the desired bactericidal or bacteriostatic effect.
The firm’s sliced-meat system relies on hydraulic pressure to deliver the antimicrobial compound, DeVoll says. It operates in the 300-1,500 slices per minute range.

Ultra pasteurization with steam or immersion is perhaps the most widely used intervention, and it is effective. But energy costs to generate steam or maintain water temperature are high, says DeVol, and that is driving RTE manufacturers to consider chemical sprays and other options. Recent changes in European food regulations to permit antimicrobial agents also are boosting interest in SLIC overseas, he adds.

Under pressure

Before settling on chemical spray, Lower Foods considered the HPP bactericidal option. On-site treatment with high pressure is cost prohibitive unless high utilization is assured, and the network of HPP tolling services is limited, particularly for processors in western states. The situation is rapidly changing, however, particularly along the eastern seaboard.

SafePac in Philadelphia and Stay Fresh Foods in Connecticut each added a second HPP press last year to meet growing demand, and two additional large-capacity presses are planned by Universal Pasteurization in suburban Philadelphia. In November, the underserved New York metro area witnessed the start-up of its first tolling service when New Jersey Frozen Storage (NJFS) commenced operations at its Nutrifresh Services division.

“It’s the new age of food and beverage,” proclaims Chris Jenkins, Nutrifresh’s director of HPP operations in Edison, N.J. “Clean labels are really pushing HPP.”

A former USDA inspector, Jenkins was first exposed to HPP 10 years ago, first while assuring regulatory compliance at Astra Foods in Upper Darby, Pa., and then at SafePac, the HPP pasteurization subsidiary of Vincent Giordano Corp. Thermal processing of packaged RTE foods costs less on a per-pound basis, he concedes, but when the added labor, preservatives and test-and-hold expenses are factored in, the difference narrows. Plus, shelf life of up to 120 days with HPP means fewer returns. “It’s reducing cost,” he says, adding, “USDA loves this.”

Nutrifresh’s 350-liter capacity press from Hiperbaric was followed in March by the installation of a 525-liter machine, the largest HPP system made and the first Hiperbaric 525L installed by a toller. Together, the machines provide more than 50 million lbs. a year of capacity. Located within spitting distance of the nation’s third largest port (and second largest point of entry for imports), Nutrafresh and NJFS’s adjacent 200,000 sq. ft. of freezer capacity are well situated to serve both importers and domestic processors of RTE meats and other food products

More arrows in quiver

Meat and poultry aren’t the only RTE foods on the market; the designation is being applied to an expanding array of convenience products. Washed, sliced and bagged fruits and vegetables qualify as RTE. So do dips. All those products are candidates for pathogenic contamination, and all have experienced sometimes-disastrous recalls (did you see our April story? Food Safety’s Smallest Challenge). The April recall of 30,000 cases of Sabra Dipping Co. products after a positive test for Listeria sent hummus processors flocking to Nutrafresh’s door.

Lethality interventions must be approved by FDA, and the agency can work in mysterious ways. Bagged spinach and iceberg lettuce can be irradiated, but bagged salads also contain other vegetables, and FDA doesn’t permit irradiation of other salad components.

“Irradiation is a viable option, but it’s dependent on getting (FDA) approval,” observes Harlan Clemmons, president and COO of Sadex Corp. Chemical changes and other side effects have to be analyzed, and that can be a long time coming: 12 years lapsed between the agency’s approval of irradiation for red meat and the go-ahead for poultry.

Defense contractor Titan Corp. built Sadex’s electron-beam treatment center in a Sioux City, Iowa, cold storage facility, opening its doors in 2000 under the Surebeam banner. Maligned as a “Frankenfood” process and dogged by public misunderstanding, irradiation never capitalized on its promise as a food safety step -- although, according to Clemmons, early adopters such as Schwan’s Home Service and Omaha Steaks continue to use Sadex’s services, as does the retailer Wegmans.

Those applications involve fresh and frozen beef, and Sioux City is in the heart of beef country. The heartland isn’t home to RTE spinach and other convenience produce, of course. Packers in California’s Salinas Valley and in Yuma County, Ariz., also are concerned with pathogen contamination. “There’s been interest,” says Clemmons, “but based on where we’re located, the timeline (for treatment) is not necessarily ideal.”

Satisfying USDA’s log-reduction hurdle rates isn’t an issue with ultraviolet light in the C wavelength, suppliers say. More problematic is finding a processor willing to validate log reduction from a UV-C system.

“Nobody wants to be first with this,” grumps Buddy Ward, business support manager with Prime Equipment Group Inc., Columbus, Ohio. He’s guardedly optimistic about an upcoming trial at a poultry operation that hopes to reduce the amount of chemical additives currently used. But until a system is permanently installed, “we’re still in proof mode.”

Whether UV-C or another intervention is used, proper design and engineering is critical. Unfortunately, some vendors have installed systems without understanding the distinct challenges in every facility, Ward complains, giving the technology a black eye in the process.

“You’re not going to kill all the bugs, but you can control them,” he concludes. That’s particularly valuable with RTE meat and poultry, where “fear of the R (recall) word” puts manufacturer “in a constant state of panic.”

Recalls don’t necessarily destroy a company, but they have doomed more than a few individuals’ careers. Slowing down the line is not an option, but there are a number of new ways to keep inspectors at bay and ready-to-eat foods safe.

Milwaukee-based American Pasteurization Co. was a pioneer in HPP tolling services in 2005. Today’s machines boast considerably more automation and increased capacities.

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