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Cut Salad Greens: How Cold is Cold Enough?

When Anne Schwartz, co-owner of Blue Heron Farm, a 20-acre organic farm in Western Washington, talks about the cut salad greens she sells at local farmers markets, she uses the term “real estate.”

“They’re very popular,” she said. “People love them. They occupy an important piece of real estate on my table.”

Tom Hohmann, co-owner of Walled Garden Produce, a 2-acre produce farm, also in Western Washington, agrees with Schwartz, saying that the cut salad greens he sells at a nearby farmers market make up an important part of his farm’s revenue.

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“They’re very major,” he said. “They’re something I have every week throughout the season. On a seasonal basis, they make up 30 or 40 percent of my sales. People like them because they’re fresher than the salad mixes in the stores.”

Their comments mirror what’s true for many small-scale farms across the nation: Cut salad mixes are popular items that attract customers and help flush money into a farm’s bottomline.

But when they look over their shoulders, the farmers see a number dogging them. That number is 41, as in 41 degrees Fahrenheit. That’s the temperature the Food and Drug Administration’s updated 2009 Food Code recommends that cut salad greens be kept at and received at by customers such as restaurants, food-service companies, and institutions, including schools and hospitals.

That has some small-scale growers worried.  In many cases, besides selling their cut salad greens at farmers markets or directly to customers through subscription plans know as CSAs, some growers also sell cut salad greens to restaurants, wholesalers, and stores.  In addition, many are interested in selling these salad mixes to schools as part of the burgeoning “farm-to-school” initiative.

Fred Berman, Small Farm Program coordinator for the Washington State Department of Agriculture, said he’s been concerned about FDA’s updated Food Code and its temperature recommendations for cut salad greens ever since the FDA released its updated version last fall.

“We must have scale-appropriate regulations or our small farms will be forced from an essential cash crop,” he said. “If cut leafy greens are designated as ‘potentially hazardous’ food, they will need to be kept at 41 degrees, a virtual impossibility without mechanical refrigeration, and not realistic for direct market vendors at farmers markets.”

He wants to keep this issue in the forefront until it’s settled with what he describes as “reasonable, scale-appropriate regulations.”

In ongoing advice to consumers, the FDA also recommends that when selecting fresh-cut produce, such as half a watermelon or bagged mixed salad greens, they should choose only those items that are refrigerated or surrounded by ice.

Farmer Tom Hohmann keeps his cut salad greens refrigerated until he takes them to the market and keeps them in a cooler at the market.  He also follows stringent food-safety practices on his farm.  Nevertheless, he said that having a refrigerated truck to get his cut salad greens to the market, which is only 1 mile from his farm, would be “way beyond our means.”

Keeping greens on ice at the market poses an additional challenge.  ”I’m willing to live up to the law,” he said, “but it would be difficult to do.  The trouble with a one-size-fits-all approach is that it makes it tough to maintain small farms and local agriculture.”

According to information provided to Food Safety News by the FDA, the decision to define cut leafy greens as “potentially hazardous food” requiring time-temperature control for safety reasons was triggered by 24 multi-state outbreaks related to cut leafy greens that occurred between 1998 and 2008.

Not only did many people become ill–sometimes seriously so–in these foodborne outbreaks, some people died.

FDA’s definition of “potentially hazardous food” includes a variety of cut lettuces and leafy greens.  But raw agricultural products such as head lettuce not processed or cut on-site are excluded from the definition.  Also excluded from the definition are herbs such as cilantro or parsley.

FDA food-safety officials say that cutting or tearing salad greens provides opportunities for microbial invasion of tissues.  Refrigerating them at 41 degrees F or less inhibits growth and promotes general die-off of pathogens such as E. coli O157:H7, Salmonella, and Listeria monocytogenes.

An easier way to understand this is to imagine the passengers on a cruise ship and compare them with pathogens that might be present in cut leafy greens.  When a leafy green is cut or torn, some of its nutrients ooze out.  And just as cruise-ship passengers line up when the buffet opens, any pathogens that might be in the cut salad mix head toward the nutrients.  It’s “supper time.”

Once attached to the surface of the leaves or internalized into cut surfaces of the leafy greens, the pathogens hold on tight.  And while some of them can be washed off, some of them hold on too tight for that.  Making matters worse, chemical sanitizers do only a marginal job of killing them.  If temperatures aren’t cold enough, these pathogens multiply.

None of this happens, of course, if there are no pathogens present.  And many produce farmers–large and small alike–follow recommended guidelines to prevent pathogens from getting on their produce in the first place.

But food scientists point out that lettuce and spinach are especially vulnerable because they grow so close to the ground, where they can come into contact with pathogens from livestock and wildlife or from contaminated irrigation water.

Greg Komar, director of Food Safety for Growers Express, said that the fresh produce industry has been controlling temperature for many years, both to preserve quality and to prevent the growth of microbes that can endanger human health.

“Many of the microbes of concern tend to grow slower–or not at all–when kept at below 40 degrees and may not multiply, which could be beneficial if the amount on the product is not at a level that will cause illness or injury,” Komar said.

In an interview with Food Safety News, Jim Gorny, senior advisor for Produce Safety at FDA’s Center for Food Safety and Applied Nutrition, said that pathogens can run rampant on cut salad greens and reach high levels of contamination in a short period of time if the greens are not kept at cold enough temperatures.

Kevin Smith, director of Retail Food and Cooperative Programs Coordination Staff at the FDA center, said that food establishments that want to protect themselves and their customers need to make sure the cut salad greens they buy aren’t “temperature abused.”

In other words, buyers need to be able to confirm that the cut salad greens have been kept at proper temperatures throughout the cold chain, starting at the farm and all the way through the distribution channel to the buyer.  From there, it’s the buyer’s responsibility to keep the cut salad greens at safe temperatures.

In coming up with the 41 degree F recommendation, Smith said the agency looked at a lot of research, a good deal of which showed that microbes can grow at temperatures as low as 45 degrees.  ”It’s a preventive approach,” he said, referring to temperature controls.  ”If you fail to keep them at a cold enough temperature, you increase the likelihood that the number of pathogens will grow. The expectation is that the product is stored and kept at 41 degrees.”

Keep it cold and move it fast pretty much sums up FDA’s time-temperature recommendations, Smith said.

Temperature aside, Gorny said that the most important thing a grower can do is to prevent pathogens from contaminating produce by following good agricultural practices and good manufacturing practices.

FDA’s Food Code, in itself, is not law.  The agency describes it as a model code and reference document designed to provide “a scientifically sound technical and legal basis for regulating food service and the retail food industry.”

As such, it is used by states, counties, and local jurisdictions to regulate an estimated 1 million restaurants, retail food stores, and vending and food-service operations in institutions such as schools, hospitals, nursing homes and childcare centers.

Most states are currently reviewing FDA’s updated Food Code.  In Washington state, Dave Gifford, manager of the state Health Department’s Food Safety Program, said the department is planning to adopt most of the updated code but hasn’t yet decided to adopt FDA’s definition of cut leafy greens as a “high priority” food item.  He said that decision probably won’t be made for another 1 1/2 years.

In California, Ralph Montano, spokesman for the state’s Department of Public Health, said that the California Retail Food Safety Coalition is currently discussing updates to the code to mirror changes to the FDA Food Code.

“It is likely that the coalition will introduce legislation early next year with the ultimate goal of making the coalition as consistent with the FDA Food Code as possible and appropriate,” Montano said.

In a Sept. 27 interview with Food Safety News, Andrea Helling, a spokesperson for Sen. Jon Tester, D-Montana, who has crafted an amendment that seeks to lessen the impact of the pending Food Safety Bill, S. 510, on small-scale food producers and processors, said the senator’s amendment would not affect FDA’s updated Food Code, which lists cut salad greens as a high-priority item.

According to the amendment, any regulations adopted by state, local, county, or other non-federal entities regarding the safe production of food would hold sway over provisions in the amendment.

The fate and the immediate timeline of the Food Safety Bill were was still up in the air Sept. 28.  Whether or not Tester’s amendment would be included in the bill was still unknown.

Meanwhile, out in the field, not everyone thinks that 41 degrees F is a temperature that should be cast in concrete, especially when it comes to small farms catering to nearby local markets.

“It is desirable to reduce risk by establishing a chill chain for fresh-cut greens but how necessary is a 41 degrees F a ‘critical point’ for small-scale handling and farmers markets — no consensus on this at all,” said Trevor Suslow, Extension research specialist at the University of California, Davis.

But Suslow was quick to say that when it comes to cut salad greens, “the cooler the better.”  ”If you’ve got something there,” he said, referring to pathogens, “the potential for foodborne illness gets worse as the temperature goes up.”

Suslow pointed to some innovative ways that small-scale growers can keep cut salad greens cold.  For example, marine coolers can be loaded with a layer of frozen gel ice with a layer of craft paper or bubble wrap on top of the gel, and the cut salad greens placed on top of that layer.

“We can harvest in 95 degrees and bring them back to Davis in 3 or 4 hours, or even longer, and the greens will be fine,” Suslow said.  ”It can be done.  There are some very creative and innovative solutions.”

Suslow said that in the past, when temperature data loggers were placed in the ice chests, the internal temperature was about 45 to 50 degrees.  Once the greens got to the lab, they went into a cold room at 34 degrees F overnight.

While the rate of division of E. coli and Salmonella at 45 or 50 degrees F  is relatively slow, Suslow said that pathogens quickly multiply at higher temperatures.

“This is especially relevant for cut salad greens in polymer packages, which is reflected in the time/temperature management requirements for food safety in the Food Code,” he said.

Suslow also pointed out that managing temperature has a double benefit.  Not only does it keep the cut salad greens safer, it also results in the best quality — crisp salad greens with good color.

The location of the farm where the salad greens are grown also comes into the picture. Suslow said that the California coastal growers don’t have to worry as much about time and temperature as the growers in the interior valleys.

“Ninety or 100 degree temperatures makes it tough,” he said.  ”Most of the small-scale growers in the interior valleys aren’t growing cut salad greens this time of the year because they don’t have access to refrigeration.”

Another option for small-scale growers is the CoolBot, which according to the company’s website, turns any brand of off-the-shelf, window-type air conditioning unit (purchased separately) into a turbo-charged cooling machine.

The website says that with a CoolBot, you can transform a highly insulated room into a walk-in cooler, keeping your vegetables fresh and thermostatically controlled cool down to 32 degrees F.

CoolBot, which uses new (patent-pending) technology that became available in 2006, was invented by a farmer, Ron Khosla, co-owner of 77-acre Huguenot Street Farm in New York. He knew he had to keep his produce cold but balked at the $3,500 it would cost to buy a used walk-in cooler.

“He invented it out of necessity,” said Patricia Parsons, one of the owners of CoolBot. Parsons said the CoolBot can also be installed in a trailer truck.

Khosla’s system  costs about $800, which includes the cost of air conditioner and the CoolBot, which on the company’s website is advertised for $299.  Parsons describes it as a perfect system for farmers because it’s affordable, easy to install, and an efficient way to cool produce.

She also said that cut salad greens are a lucrative crop for farmers and that keeping them cool is important both for quality and food safety.

John Hendrickson, an outreach specialist for the Center for Integrated Agricultural Systems at the University of Wisconsin, has a small vegetable farm, Stone Circle Farm, which supplies white-tablecloth restaurants with produce.

He describes himself as a “strong advocate of farmers of any size having refrigerated storage.”

“If you’re in the business of selling produce, having some kind of cold storage is a necessity,” he said.  ”I know that some growers disagree, but I think they’re operating under antiquated and mistaken thinking.”

But he also believes that one of the main reasons cut salad greens have fallen under additional scrutiny is based on the nation’s food distribution system, which involves hauling lettuce and salad greens, primarily from the Salinas Valley in California, to far-flung destinations across the nation.

He also believes that the cut salad greens sold at farmers markets or through CSA subscription programs are very different than those sold by the big farming operations in the Salinas Valley, where most of the nation’s lettuce and salad greens are grown.

He predicts that even if there are exemptions for small-scale growers in some of the impending food-safety rules, the rules will eventually impact all growers.

“Most of the food-safety guidelines are things all growers should be paying attention to,” he said. “Buyers are becoming increasingly aware of them.”

When asked about the CoolBot, he said he’s seriously considering getting one for his second cooler.  ”I’ve heard growers say that it’s made it possible for them to afford a walk-in cooler,’ he said.

Steve Warshawer, owner of Beneficial Farms in New Mexico, which has the oldest CSA in the state, also serves as a consultant on food-safety issues at the Wallace Center’s National Good Food Network.

He believes that considerations such as the distance between the farm and its customers, the farm’s growing practices, its soil and climate, how soon the produce is delivered to customers after it’s been harvested, and how the customers handle it after they receive it need to be factored into the equation.

“There’s not enough meaningful, discerning science on this,” he said, referring to the multitude of variables involved.

He said he doesn’t keep his cut salad greens at 41 degrees F, but he does keep them cool.

But if 41 degrees F does become a requirement, he said farmers are an innovative group and will deal with it.

Even so, he thinks that having to be under the gun of broad-brushed regulations designed for the Salinas Valley is “a terrible way to go.”

“We’ll adapt, but it doesn’t mean it’s right,” he said.  ”The idea that one-size-fits-all is preposterous.”

In his view, when something gets to the regulatory stage, it gets “dumbed down for big ag.”

“That’s our loss,” he said. “It represents a loss of opportunity. In my view, we’re all in trouble because this is getting regulated. The worst-case scenario will be the rule.”

But many “big ag” representatives rankle at the idea that the size of a farm should determine what food-safety guidelines should be required.

“To suggest that a smaller operation should have different standards for food production is akin to saying that a small restaurant shouldn’t have the same food-safety standards or rules as a large restaurant,” said a responder from Green Giant Fresh in a public-comment letter to the FDA about its fresh produce rule, which is still being worked on and has not yet been released.

As far as Ray Gilmer, vice president for Communications at United Fresh, is concerned, FDA’s recommended 41 degrees F or lower is the way to go, no matter the size of a farm.

“What we’re facing in D.C. is a growing discussion on Capitol Hill about making a distinction between small and large farms,” he said.  ”We need to be careful not to do that.  We firmly resist the idea that there should be a difference.  The marketplace needs one standard.  Our end game is to boost consumer confidence in the safety of produce.  Science should dictate so consumers aren’t wondering about the safety of their food.”

So when all is said and done, just how safe are salads anyway?

During a food-safety conference in Wisconsin last year, Sam Beattie, who until recently was an Iowa State University Extension food-safety specialist, provided some reassuring numbers.

He told the farmers attending the conference that the odds of getting sick from a serving of fresh lettuce-spinach was 1 in 5.5 million, compared with the odds of getting struck by lightning, which are 1 in 310,000.

Nutritionists praise leafy greens for containing an array of healthy components, among them, fiber, protein, calcium, Vitamin A, B vitamins, Vitamin C, Vitamin K, iron and chlorophyl.

Even so, some people think that it would be far safer to buy lettuce and other salad ingredients and cut them up at home instead of buying bagged salad greens.

“We’re not using our noggins when we have people far away from us making our salads,” said Tom Willey, co-owner of T & D Willey Farms in Madera, CA.

Be that as it may, views such as that are bucking up against a strong headwind.  According to a recent report on bacteria and bagged salads done by the Consumers Union in Yonkers, NY, the bagged salad industry has grown rapidly in the past 20 years.  In 1989, Fresh Express created the first mass-produced, ready-to-eat bagged salads.  From that point on, says the report, the fresh-cut, bagged salad industry took off, with industry experts putting current sales close to $3 billion a year.

© Food Safety News
  • http://www.esiqual.com Phil Ventresca

    I think the folks who are lobbying for scale-appropriate temperature regulations ought to spend their time trying to convince the microbial leaders their groups need to adopt scale appropriate growth ranges. It should be a lot easier to convince savvy regulators and congressional leaders to promulgate scale-appropriate temperature regs and guidelines when proponents achieve the first logical goal (eliminate the potential for outgrowth).

  • Jim Schmidt

    Bogus argument for “small” growers not meeting temp control. If I have a local resident want to open a restaurant they don’t have to comply with all the laws I require McDonald’s to because they are small and local? Nope, the law is equally applied, if you want to get into business you need to look at what the costs will be, Don’t whine about them and ask to compromise public health and safety.

  • Chandler Briggs

    “According to information provided to Food Safety News by the FDA, the decision to define cut leafy greens as “potentially hazardous food” requiring time-temperature control for safety reasons was triggered by 24 multi-state outbreaks related to cut leafy greens that occurred between 1998 and 2008.
    Not only did many people become ill–sometimes seriously so–in these foodborne outbreaks, some people died.”
    How large are the farms that have made people sick from eating salad greens?