Most Active Stories
Thu April 19, 2012
The Great Salad Microbe Hunt, California-Style
Originally published on Wed January 9, 2013 3:15 pm
When you tear open a bag of prewashed salad greens, do you worry that this superhealthful fast food could actually make you sick?
The companies that sold you that salad do worry about it. Because no matter how much they try to keep dangerous microbes out of that bag, they can't seem to guarantee that they've caught every one.
This week, for instance, Dole Foods recalled thousands of bags of lettuce after a few leaves from one of those bags turned up positive for Salmonella bacteria.
In a quest to find out why contamination remains a problem, and what companies are doing about it, I went to one of America's great centers of salad-greens production: the Salinas Valley of California.
I looked up a man who's in charge of making sure that many of those greens are safe to eat: Will Daniels, senior vice president for operations and organic integrity at Earthbound Farm, based in San Juan Bautista.
Earthbound Farm sells bags of ready-to-eat organic greens by the tens of millions. Six years ago, it was the central figure in a national food safety scare.
It sold some spinach that carried a deadly microbe: E. coli O157:H7. The spinach went all over the country. It made at least 200 people sick. Three people died.
"I was at the center of the investigation and really took it very hard," says Daniels. "It was just a real tough time to go through, and something that I don't ever want to go through again."
But making sure it never happens again is really hard because, despite an intensive investigation, no one knows exactly what caused it to happen the first time. "There was no smoking gun, if you will," says Daniels.
Investigators found E. coli bacteria that matched the microbes that were making people sick on a ranch that was one of Earthbound's suppliers. But those bacteria were in animal feces a mile from the spinach field, Daniels says, "with no clear indication of what caused the contamination from a mile away to get into the spinach field itself."
Fighting microbes, in fact, is a little like boxing blindfolded. You can't see those disease-causing bacteria, but you know that they're out there, in lots of places.
For instance, they could be in the small stream, lined with bushes and trees, right beside the lettuce field where Daniels and I are standing. "Deer might be moving through here; wild pigs might be moving through here," Daniels says, nodding toward the stream. "Small rodents, rabbits, squirrels, things like that." Where there are animals, there is animal feces, possibly with disease-causing E. coli or Salmonella.
Or, look across the valley at those hillsides. They're pretty, but watch out: Cattle graze there. Their manure could wash down into the fields, or drain into ponds that are used to supply water for irrigation.
And what if there are frogs in those irrigation ponds? They can carry disease, too.
"Unfortunately, it looks like every animal is suspect," says Bob Martin, general manager of Rio Farms, in King City, Calif.
Even birds. "Birds are a big issue! They carry human pathogens, and we can't put diapers on them. We can't dome our fields; there's nothing we can do, short of trying to scare them away," says Martin.
Yet after the spinach disaster of 2006, California's big-time sellers of salad greens knew they had to do something. So they got together and hammered out a whole catalog of rules for growers. The rules amount to a manual for building a kind of anti-microbial Berlin Wall around their fields of greens.
Keeping The Birds And Beasts Away
Some fields in the Salinas Valley now have fences. Almost all of them, like the one Daniels took me to see, are surrounded by a no man's land of bare dirt to help detect any animal traffic. "You would be able to see animal tracks coming across it pretty easily," says Daniels.
If tracks do show up, or actual animal feces, any leafy greens around that spot doesn't get harvested. Some buyers tell their suppliers to discard everything within five feet; others say 50 feet.
Lettuce fields now have to be separated from cattle pastures, and throughout the valley, next to lettuce fields, you see white plastic pipes. Inside those pipes are mouse traps.
And the birds? Vegetable buyers won't take anything from the area directly under power lines — because birds like to sit there. Even trees, next to fields, are considered suspect.
There's a lot of debate about how effective some of these precautions are. They probably reduce the risk of contamination, but they don't eliminate it entirely.
"When it comes to food safety, if it's grown outdoors, forget it, there's no such thing as zero tolerance," says Bob Martin. "And everybody knows that, except for some food safety personnel of the big food buyers."
Cleaning and Washing
That's not quite the end of the story. The companies that sell bagged greens, in particular, have set up a few more lines of defense.
The first is washing. Mark Borman, president of Taylor Farms, took me inside one of his company's salad-packing plants in Salinas. This facility handles 10 million pounds of produce every week. It feels like a giant refrigerator and smells like a swimming pool, because the wash water is heavily chlorinated.
Borman points to one of the giant washing machines and shouts over the noise: "It works just kind of like a Jacuzzi whirlpool, so it kind of sucks the product under the water, tumbles it around, adds agitation."
Taylor Farms has added something new to the company's wash systems: some chemicals, including propylene glycol and phosphoric acid, which make the chlorine more effective. The company calls it "SmartWash," and it's now selling the salad cleanser to other companies, too. The new system still probably can't kill all the microbes on every contaminated lettuce leaf. But tests show that it does keep wash water from spreading those microbes from one leaf to thousands of others. Some experts think such "cross contamination" helped cause the poisoned spinach of 2006.
That's one line of defense. Earthbound Farms, being organic, can't use this new system yet. It uses standard chlorine. But it does run an impressive testing program. It samples leaves from every bin of freshly picked lettuce or spinach, and it also takes samples from the washed greens that are ready to ship.
"It is a true test-and-hold program, so we have to wait to get the negative results before we put it on a truck. Any positives go to the landfill," says Daniels.
There still are positives. Not very often, but every five weeks or so, one of these tests catches a sample that's contaminated with disease-causing E. coli or Salmonella.
It's impossible to test every leaf, so it probably means that some contaminated lettuce or spinach leaves are getting through. But the sampling program should catch any major contamination.
Ultimately, that's what these systems — the barriers around fields, better wash systems, testing programs — are supposed to achieve. They can't prevent every isolated case of contamination, but they are supposed to make sure that there are no more big, nationwide outbreaks of disease among people who chose to eat that healthful salad.
MELISSA BLOCK, HOST:
This is ALL THINGS CONSIDERED from NPR News. I'm Melissa Block.
AUDIE CORNISH, HOST:
And I'm Audie Cornish.
We're going to take some time now to talk food. We've got a new bead here at NPR focusing on the health, science and growing of everything we eat.
And with us now are the two correspondents serving up the stories behind what's on our plates - Dan Charles. Hi there, Dan.
DAN CHARLES, BYLINE: Hi.
CORNISH: And Allison Aubrey. Hi, Allison.
ALLISON AUBREY, BYLINE: Hi, there.
CORNISH: So Allison, let's start with you. What's your new beat really all about?
AUBREY: Well, this is really an extension of something I've been covering for six or seven years. I have looked at the science of nutrition, sort of how food works in our bodies. And what I've realized is, it's really hard to answer these questions - or by virtue of trying to answer these questions, it opens up like, a whole conversation about where food comes from. It gets into politics and culture and business. So it's a much broader beat. And we're hoping to look at it on all fronts.
CORNISH: So Dan, what does that mean in terms of actual stories? What are you going to come up with?
CHARLES: Well, the first thing we should say is, it's not going to be just on the radio. We have got this new NPR food blog; it's called The Salt. You can find it at npr.org/salt. We contribute to it, but lots of colleagues around NPR contribute to it. It's led by our fearless leader, our editor Alison Richards.
But as far as stories on the radio, we're going to hear about palm oil - how it fell out of favor, how it's making a comeback, how that might not be such a good thing. We'll talk about salt - what happens if companies try to reduce the amount of salt in your soup? But first up, today we're actually going to talk about salad.
(SOUNDBITE OF RUSTLING)
CHARLES: So here's his bag of baby spinach.
CORNISH: Oh, here we go
CHARLES: Ok. So when you open a bag like this and eat it yourself, do you ever worry that it's going to make you sick?
CORNISH: Yeah. You know, a few years ago there was stuff about recalls. And, of course, just a few days ago, Dole foods recalled thousands of bags of prewashed lettuce. So yeah, I'm a little weirded-out sometimes.
AUBREY: So does that mean we need to wash this stuff?
CORNISH: I watch it every time. I just don't know if it helps.
(SOUNDBITE OF LAUGHTER)
CHARLES: It says prewashed, but washing might actually help because no matter what companies do, to get all bacteria always out of a bag like this, the microbes still show up every once in a while. And I wanted to find out why.
So I went to a part of the country where an awful lot of these salad greens are grown. I went to the Salinas Valley in California, out to a lettuce field with a man named Will Daniels. Because Will Daniels is the man who's supposed to make sure that this bag of spinach is safe to eat.
WILL DANIELS: I'm the senior vice president of operations and organic integrity, with Earthbound Farm.
CHARLES: His company is based in San Juan Bautista, California, at the northern edge of America's great center of salad greens production. Earthbound Farm sells bags of ready-to-eat organic greens by the tens of millions. And six years ago, it sold some spinach that carried a deadly kind of E. coli bacteria. The spinach went all over the country. It made at least 200 people sick. Three people died.
DANIELS: I was at the center of the investigation and really, took it very hard. It was just a real tough time to go through, and something that I don't ever want to go through again.
CHARLES: But making sure it never happens again - that is really hard. Consider this: We still don't know, exactly, what caused that spinach outbreak.
DANIELS: There was no clear smoking gun, if you will.
CHARLES: Government investigators found a bacteria that matched the microbes that were making people sick on a ranch that was one of Earthbound's suppliers. But the bacteria showed up in wild pig feces a mile from the spinach field.
DANIELS: And no clear indication of what caused the contamination from getting, a mile away, into the spinach field itself.
CHARLES: There's one thing the producers of leafy greens do know. Those disease-causing bacteria are out there in lots of places. For instance, they could be in the small streambed lined with bushes and trees, right beside this freshly planted lettuce field where we're standing.
DANIELS: Deer might be moving through here; a wild pig might be moving through here; small rodents; rabbits, squirrels, things like that.
CHARLES: And where there are animals, there are animal feces, possibly with disease-causing E. coli or salmonella. Or look across the valley at those hillsides. They're pretty but watch out - cattle graze there. Their manure could wash down into the fields, or drain into ponds that are used to supply water for irrigation. And what if there are frogs in those irrigation ponds? They can carry disease, too.
BOB MARTIN: Unfortunately, it looks like every animal is suspect.
CHARLES: Bob Martin is general manager of Rio Farms in King City, California, and he says don't forget about the birds.
MARTIN: Birds are a big issue. They carry human pathogens, and we can't put diapers on them. We can't dome our fields. There's nothing we can do short of just trying to scare them away.
CHARLES: After the spinach disaster of 2006, big-time vegetable growers in California knew they had to do something. So they got together and hammered out a whole catalog of rules; ways to build a kind of anti-microbial Berlin Wall around their fields of greens.
Some fields now have fences. Almost all of them, like the one Will Daniels took me to see, are surrounded by a no-man's land of bare dirt to help detect any animal traffic.
DANIELS: You would be able to see animal tracks coming across it pretty easily.
CHARLES: If tracks do show up, or animal poop, any leafy greens around that spot don't get harvested. Some food buyers say discard everything within 5 feet; others say 50 feet. Lettuce fields now have to be separated from cattle pastures. And everywhere up and down the Salinas Valley, you'll see white, plastic pipes. Inside those pipes are mouse traps.
As for the birds? Well, vegetable buyers won't take anything from the area directly under power lines because birds like to sit there. But Bob Martin says even with all that, you cannot expect perfection.
MARTIN: When it comes to food safety, if it's grown outdoors, forget it. There's no such thing as zero tolerance. And everybody knows that except for - sort of - some food safety personnel of the big food buyers.
(SOUNDBITE OF LAUGHTER)
CHARLES: This is not quite the end of the story. Fresh-cut salad companies have set up a few more lines of defense. First, better washing.
(SOUNDBITE OF MACHINERY)
MARK BORMAN: You can see baby lettuce here; romaine being processed there; iceberg being processed over there.
CHARLES: Mark Borman, president of Taylor Farms, is showing me around one of his company's salad-packing plants in Salinas, California. It feels like a giant refrigerator, and smells like a swimming pool because the wash water is heavily chlorinated.
BORMAN: So it works just - kind of like a Jacuzzi whirlpool. So it kind of sucks the product under the water, tumbles it around, adds agitation
CHARLES: Taylor Farms has added something new to its wash systems - some chemicals that make the chlorine work better. It still probably will not kill all the microbes on every contaminated lettuce leaf. But tests show it will keep washwater from spreading those microbes from one leaf to thousands of others. That may have happened with the poisoned spinach of 2006. That's one approach.
Earthbound Farms, being organic, can't use this new wash system yet. It uses standard chlorine. But it does run an impressive testing program. It samples leaves from every bin of freshly picked greens, and it also takes samples from the washed greens that are ready to ship. Will Daniels.
DANIELS: It is a true test-and-hold program, so we have to wait until we get the negative results to put it onto a truck. Any positives go to the landfill.
CHARLES: And yes, every five weeks or so, there is a positive - a sample that's contaminated with disease-causing E. coli or salmonella. They can't test every leaf so that probably means some contaminated lettuce or spinach is getting through.
But these systems should catch a major contamination. That's what the washing, and the testing, are supposed to achieve. No more big, nationwide outbreaks of disease because people ate that healthy salad.
Dan Charles, NPR News.
CORNISH: OK, so what do we do now? You're in the market; you reach for that bag of lettuce. Maybe it's freshly cleaned spinach, a tightly wrapped head of iceberg, maybe three Romaine heads all in a row. Now they're toiling away in your fridge, and you want to know what can you make tonight that will be delicious?
Well, Molly Wizenberg has some ideas. She's created the award-winning food blog called Orangette. And she's on the line from KUOW in Seattle.
Hey there, Molly.
MOLLY WIZENBERG: Hi.
CORNISH: So first things first, how do we keep the lettuce that we bought - with such good intentions - from rotting in the fridge?
WIZENBERG: So, I'm very glad to get to talk about sort of the pleasure angle of this story.
(SOUNDBITE OF LAUGHTER)
CORNISH: Yeah, there is pleasure to be had.
(SOUNDBITE OF LAUGHTER)
WIZENBERG: Yes. Yes. So, I am as guilty as anybody else of bringing a beautiful head of lettuce home, and letting it fester in the drawer. So the first thing that I always do when I bring home a head of lettuce is I go ahead - and the minute I take it out of the shopping bag, I wash it. I layer it in paper towels; put it in a closed, Ziploc bag; and it's ready to go whenever I want it. Easy and enjoyable.
CORNISH: Oh. So is my salad spinner useful at all?
WIZENBERG: I think so, absolutely.
CORNISH: OK, good.
WIZENBERG: I grew up using a salad spinner, and I love it.
CORNISH: So what kind of lettuce do you love this time of year?
WIZENBERG: So I am a big fan of bib or butter lettuce. It's great at any time of year. But particularly at this time of year, we're starting to get some that's really fresh, really delicate; these soft, velvety leaves.
CORNISH: And it's sort of a bright green. Usually, you see - you see it - I feel like with - it looks like the roots are still on the bottom, or something.
WIZENBERG: Yeah, you can buy it - sometimes they call it "still living." At some grocery stores, it comes with the roots still on it. Sometimes the leaves are a little bit tinged in purple. It's really beautiful.
CORNISH: Well, I've got a little lettuce here, too. I don't know if you can talk about them. One of them is red leaf...
WIZENBERG: Yeah, yeah.
CORNISH: ...which has the kind of purplish tinge.
WIZENBERG: Yeah. So red leaf is one of those that I can almost always find in the grocery store. It's got these really beautiful, frilly leaves and it's nice, in particular, when the heads are small. And I like to use it at this time of year, in particular, with all of these bright, crunchy spring vegetables we're getting - maybe some blanched asparagus, some shaved radish, maybe some chives. It makes a beautiful salad, both visually and taste-wise.
CORNISH: So what's a salad without the dressing? What ideas do you have for us, for something to go with all this roughage?
WIZENBERG: So I think that - I think one of the hallmarks of a really comfortable home cook is having a dressing formula that you can pull out at any time. So my dressing formula - what I almost always use is a one-to-three-to-five formula. It's one tablespoon of Dijon mustard, three tablespoons vinegar of your choice, and about five tablespoons of olive oil. And then depending on the vinegar, you may want to scale up a little bit on the oil, maybe even up to seven tablespoons.
But basically, you're going to get this really wonderful, bright, mustardy dressing that I, in particular, like on these spring lettuces because - I don't know, who doesn't love a little bit of bright, vinegary kick on your leafy greens, a little bit of mustard? So that's my favorite.
CORNISH: That's good to know. My favorite dressing usually comes purchased from the store, so I appreciate getting a recipe.
(SOUNDBITE OF LAUGHTER)
CORNISH: All right, Molly, that was great. Thank you for talking with us.
WIZENBERG: Sure. My pleasure.
CORNISH: That's Molly Wizenberg, food blogger and commentator on the podcast Spilled Milk. You can find Molly's suggestions for how to prepare greens and dressings by going to NPR's food blog, called The Salt. That's at NPR.org.
Now, as we mentioned earlier, we'll be talking more about food on this program, and delving into the stories behind what we eat. And we want to hear from you. Is there a favorite family recipe you've tried to re-create, but there's always something missing? Grandma's apple pie, your uncle's favorite chili? Well, we'd like to help you re-create your lost recipe.
Molly Wizenberg gave us one of hers. She's been on the hunt for the perfect recipe from her late father - his french toast.
WIZENBERG: What I did was, I took his sort of rough notes. I looked up a lot of recipes for french toast. And then I just got to work - sort of blending some of them, trying to sort of dig into my taste memory and get back to the one that was closest to his. And the truth is, I don't know if what I have is exactly what he used to make. But it tastes the way I remember it tasting, and it's been incredibly satisfying for me to get back to that.
CORNISH: Share your lost recipe with us, and a bit about the original cook. Just go to NPR.org and click on Contact Us, and remember to put Lost Recipe in the subject line. We've lined up some kitchen detectives to help you get your family dish back on the table.
(SOUNDBITE OF MUSIC) Transcript provided by NPR, Copyright National Public Radio.