How Clean is Your Spinach? 
 
 Researchers believe peaks and valleys in baby spinach leaves could be a key reason why there have been numerous bacterial outbreaks involving leafy green vegetables 
 
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 Nichola Kinsinger, a post-doctoral researher at UC Riverside. 
 
 RIVERSIDE, Calif. (www.ucr.edu) — Ever wonder what the words triple-washed or pre-washed on a bag of baby spinach mean? 
 
 Not much according to engineers at the University of California, Riverside. They discovered that small peaks and valleys in baby spinach leaves could be a key reason why there have been numerous bacterial outbreaks involving leafy green vegetables. 
 
 Currently, disinfectant is put into the rinse water, and not specifically applied to the leaf surface. The researchers in the Bourns College of Engineering found that because of the varied topography of the spinach leaf nearly 15 percent of the leaf surface may reach concentrations as low as 1,000 times that of the bleach disinfectant being used to rinse it. 
 
 As a result, as the leaves move through the processing facility after being rinsed the bacteria may continue to live, grow, spread, and contaminate other leaves and surfaces within the facility. 
 
 Following rinsing under the low bleach condition, upwards of 90 percent of adhered bacteria were observed to remain attached to and survive on the leaf surface. 
 
 “In a sense the leaf is protecting the bacteria and allowing it to spread,” said Nichola M. Kinsinger, a post-doctoral researcher working with Sharon Walker, a professor of chemical and environmental engineering. “It was surprising to discover how the leaf surface formed micro-environments that reduce the bleach concentration and in this case the very disinfection processes intended to clean, remove, and prevent contamination was found to be the potential pathway to amplifying foodborne outbreaks.” 
 
 Kinsinger will present her research on August 19 at the 250th American Chemical Society National Meeting & Exposition. The talk is called, “Is our salad safe? Efficacy of disinfection techniques to decontaminate spinach leaves and reduce cross-contamination.” 
 
 Kinsinger is also writing a paper, co-authored by Walker and Madeline Luth, an undergraduate student, about the findings. It will soon be submitted for publication. 
 
 The Center for Disease Control estimates that 1 in 6 Americans become ill and 3,000 die annually from foodborne diseases. Additionally, this causes and an estimated over $75 billion per year loss for the food industry. 
 
 Past research has found about 20 percent of single food commodity outbreaks from 2003 to 2008 were attributed to leafy green produce. Contamination of such minimally processed and ready-to-eat produce is of concern since it is frequently consumed uncooked or raw. 
 
 One of these outbreaks, involving spinach, occurred in California in 2006. In all, 199 people in 26 states were infected with the outbreak strain of E. coli. Three died. 
 
 Currently, the industry standard is to add 50 to 200 parts per million of bleach to the water used to rinse leafy green vegetables. But that is just a recommendation, not a requirement or regulation, Kinsinger said. 
 
 For the research, Kinsinger and Walker designed a parallel plate flow chamber system to evaluate in real time the attachment and detachment of pathogens to the spinach in realistic water chemistries and flow conditions. 
 
 Their work focused exclusively on baby spinach, however the issue of reduced bleach concentration across the leaf surface and other surfaces within the processing facility translates beyond the specific scenarios tested and demonstrates the limitation of bleach disinfection causing significant concern over public health. 
 
 Future research will focus on a broader range of foods, surfaces in processing facilities and pathogen types, Kinsinger said. 
 
 Despite their findings, Kinsinger notes that the United States has one of safest food supply system. Still, she says, “I recommend rinsing those leaves.” 
 
 Kinsinger is a Riverside native who earned her bachelor’s and Ph.D. from UC Riverside. She has a postdoctoral research fellowship through the USDA National Institute for Food and Agriculture under the Agriculture and Food Research Initiative. Luth is a 2015-16 UCR Chancellor Research Fellow. 
 
 Archived under: Science/Technology, Bourns College of Engineering, Madeline Luth, Nichola Kinsinger, press release, Sharon Walker 
 
 Top of Page ||||| If you nosh on spinach right out of the bag, you might want to think twice. (Photo: iStock) 
 
 Labels like “thoroughly washed” and “triple washed” make us feel comfortable chowing down on pre-washed baby spinach straight from the container. But researchers from the University of California, Riverside, say we might want to rethink that habit. 
 
 They discovered that the small peaks and valleys in baby spinach leaves can harbor bacteria — even during the washing process they often undergo in food-processing plants. This, researchers say, could be an important reason why there have been several outbreaks of E. coli and salmonella in pre-washed baby spinach. 
 
 The findings were presented Wednesday at the American Chemical Society National Meeting & Exposition. 
 
 Pre-washed baby spinach is typically treated using a bleach disinfectant. But, researchers discovered, the shape of the baby spinach leaf means that 15 percent of the leaf’s surface may only see a very small percentage of the disinfectant. That remaining bacteria, which can include E. coli, salmonella, and Listeria monocytogenes, can survive, grow, and spread to the other leaves. 
 
 Here’s the freaky part: After researchers rinsed baby spinach leaves under the typical disinfectant, nearly 90 percent of bacteria were still attached to (and alive on) the leaf’s surface. 
 
 Related: Why Recent Food Poisoning Outbreaks All Began in This One State 
 
 While the news is shocking to most people, “this is not a surprise to many of us in the food safety arena,” Mike Doyle, director of the Center for Food Safety at the University of Georgia, tells Yahoo Health. 
 
 The danger in this bacteria remaining is that it can cause outbreaks of food-borne illness, which he says are more common than we realize. “There are many outbreaks that go unreported or uninvestigated because the CDC can’t investigate them all,” he says. 
 
 The realization that spinach could cause food-borne illness reached national consciousness in 2006, when nearly 200 people from 26 states were infected with a strain of E. coli contracted from fresh spinach. Three people died from that outbreak. Fresh spinach was also involved in an outbreak in 2012 that infected 33 people in five states. 
 
 Related: Whole Foods Tops List Of Companies Forced To Recall Food 
 
 Unfortunately, washing your pre-washed baby spinach before eating it doesn’t make a difference, says Benjamin Chapman, PhD, an assistant professor and food safety extension specialist at North Carolina State University. 
 
 “Rinsing isn’t going to do a whole heck of a lot for food safety,” Chapman tells Yahoo Health — it just may remove dirt or other physical objects that you can see. Cooking the spinach, however, will kill potentially harmful bacteria. 
 
 But what about the whole “triple wash” label? Does that make pre-washed spinach safer? Chapman says there’s some confusion about what it means. Companies don’t triple wash spinach to disinfect it, he explains — they do it to reduce the likelihood of cross-contamination from one piece of spinach to another during the washing process. 
 
 So, what does this mean for consumers? Experts are mixed. Doyle says he doesn’t eat raw spinach because of the risks, but Chapman eats pre-washed baby spinach out of the bag. 
 
 “From a health standpoint, eating fruits and vegetables sometimes outweighs the risk,” Chapman says. However, he says he wouldn’t feed raw spinach to a person who is immunocompromised or elderly, just to be safe. 
 
 Read This Next: 5 Fruits and Vegetables Linked to Recent Food-Borne Illness Outbreaks 
 
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– If you don't wash the pre-washed spinach you buy from the store, you may want to stop reading. Actually, even if you do wash your spinach, you still may want to stop here. According to new findings by food safety researchers out of the University of California, Riverside, bacteria such as E. coli and salmonella can survive even the bleaching process used in food processing plants thanks to the many folds and contours in a typical spinach leaf. In fact, 15% of a typical spinach leaf sees itself exposed to only trace amounts of disinfectant. What remains can be much more than that: "Following rinsing under the low bleach condition, upwards of 90% of adhered bacteria were observed to remain attached to and survive on the leaf surface," per the university. Unfortunately, once those bacteria are there, they tend to multiply and spread, reports Yahoo Health. Worse still, "Rinsing isn’t going to do a whole heck of a lot for food safety," says Benjamin Chapman, a food safety specialist at North Carolina State University. Indeed, a second food safety expert tells Yahoo Health he won't eat raw spinach because of the risks; the CDC estimates that about 17% of Americans become ill and 3,000 die every year from foodborne diseases. Chapman says that while at-home washing essentially just removes bits of dirt and debris, cooking the spinach does eliminate the bacteria. These findings, which have not yet been submitted for publication but were Thursday presented at the 250th American Chemical Society National Meeting & Exposition, have implications beyond spinach since many leafy greens have lots of grooves. (Researchers have called this the No. 1 powerhouse vegetable.)