Monday, February 1, 2010
Posted in
Health
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The short answer: Wood cutting boards are safer.
The long answer: About twenty years ago there was a rash of news stories telling the public to use plastic cutting boards because they are less prone to bacterial contamination than wood cutting boards. At the time, I was suspicious of the stories, for a couple reasons: First, no scientific evidence was given as to why plastic was safer. Second, I knew that propaganda from various industries is often picked up by news organizations and presented to the public as fact, and there was something about these stories that sounded like they were coming from the plastics industry. But I had no proof either way, so I did what I had always done, which was to do my cutting on a plate.
Years later, however, the University of California did some tests, and they found that wood cutting boards are safer. Here's why: Wood is not a good environment for bacteria to grow on. Wood is absorptive; and as the wood dries (after being used), it sucks the moisture out of the bacteria on the surface, and the bacteria die. That doesn't happen with plastic, since plastic doesn't absorb moisture. As you use a plastic cutting board, you put hundreds of little cuts into the surface. Water and food get into the cuts and remain there, and bacteria breed in those crevices. Since the plastic isn't absorptive, the crevices can remain moist for weeks, and that allows the bacteria to grow. Then, when you use your cutting board again, the bacteria contaminates the new food you put on it.
The scientists did find that if the plastic cutting board was new, and had no cuts in it, it could be cleaned completely by hand. They also found that it could be adequately cleaned in a dishwasher even if it had cuts in it (presumably because the dishwasher heats the dishes while drying them). But once the plastic board had many cuts in the surface, it could never be cleaned adequately by hand. Their exact words were, "plastic surfaces that were knife-scarred were impossible to clean and disinfect manually". This means that if you are using a plastic cutting board, you must wash it in the dishwasher constantly in order to keep it safe. (And you must use the high heat setting.)
The researchers didn't say how long a wood board had to dry before it was free from bacteria, but they said the time was "short" (which suggests that the wood didn't have to be completely dry). They did find bacteria present inside the boards, but in order to get to that bacteria, the wood had to be gouged or cut very deeply. The bacteria inside the boards didn't appear to be multiplying, and the researchers expected it to eventually die out (presumably as the wood got dryer and dryer). Their exact words were, "Although the bacteria that have disappeared from the wood surfaces are found alive inside the wood for some time after application, they evidently do not multiply, and they gradually die."
The researchers tested many kinds of plastic and wood, and the results were the same for all of them.
So what should you do? First, always use a wood cutting board. If you frequently cut up raw meat, wipe the board down with bleach and then let it dry (at least partially). That should be adequate to make it completely safe. Even if you don't use bleach, it should be safe once it is completely dry. If you do a lot of chopping in the kitchen, it can't hurt to have two cutting boards, one for vegetables and one for raw meat.
As for using a plate, that is probably the safest method (in terms of preventing bacterial contamination). However, china is so hard that it will dull your knives, and the knives will eventually damage the plates.
More: At the end of the report that I read, which can be found here, they mention a study which was done in California which confirmed their work. People who used wood cutting boards were less than half as likely to contract salmonella, while people who used plastic cutting boards were twice as likely to contract salmonella. How regularly the plastic cutting boards were cleaned didn't make a difference.
The long answer: About twenty years ago there was a rash of news stories telling the public to use plastic cutting boards because they are less prone to bacterial contamination than wood cutting boards. At the time, I was suspicious of the stories, for a couple reasons: First, no scientific evidence was given as to why plastic was safer. Second, I knew that propaganda from various industries is often picked up by news organizations and presented to the public as fact, and there was something about these stories that sounded like they were coming from the plastics industry. But I had no proof either way, so I did what I had always done, which was to do my cutting on a plate.
Years later, however, the University of California did some tests, and they found that wood cutting boards are safer. Here's why: Wood is not a good environment for bacteria to grow on. Wood is absorptive; and as the wood dries (after being used), it sucks the moisture out of the bacteria on the surface, and the bacteria die. That doesn't happen with plastic, since plastic doesn't absorb moisture. As you use a plastic cutting board, you put hundreds of little cuts into the surface. Water and food get into the cuts and remain there, and bacteria breed in those crevices. Since the plastic isn't absorptive, the crevices can remain moist for weeks, and that allows the bacteria to grow. Then, when you use your cutting board again, the bacteria contaminates the new food you put on it.
The scientists did find that if the plastic cutting board was new, and had no cuts in it, it could be cleaned completely by hand. They also found that it could be adequately cleaned in a dishwasher even if it had cuts in it (presumably because the dishwasher heats the dishes while drying them). But once the plastic board had many cuts in the surface, it could never be cleaned adequately by hand. Their exact words were, "plastic surfaces that were knife-scarred were impossible to clean and disinfect manually". This means that if you are using a plastic cutting board, you must wash it in the dishwasher constantly in order to keep it safe. (And you must use the high heat setting.)
The researchers didn't say how long a wood board had to dry before it was free from bacteria, but they said the time was "short" (which suggests that the wood didn't have to be completely dry). They did find bacteria present inside the boards, but in order to get to that bacteria, the wood had to be gouged or cut very deeply. The bacteria inside the boards didn't appear to be multiplying, and the researchers expected it to eventually die out (presumably as the wood got dryer and dryer). Their exact words were, "Although the bacteria that have disappeared from the wood surfaces are found alive inside the wood for some time after application, they evidently do not multiply, and they gradually die."
The researchers tested many kinds of plastic and wood, and the results were the same for all of them.
So what should you do? First, always use a wood cutting board. If you frequently cut up raw meat, wipe the board down with bleach and then let it dry (at least partially). That should be adequate to make it completely safe. Even if you don't use bleach, it should be safe once it is completely dry. If you do a lot of chopping in the kitchen, it can't hurt to have two cutting boards, one for vegetables and one for raw meat.
As for using a plate, that is probably the safest method (in terms of preventing bacterial contamination). However, china is so hard that it will dull your knives, and the knives will eventually damage the plates.
More: At the end of the report that I read, which can be found here, they mention a study which was done in California which confirmed their work. People who used wood cutting boards were less than half as likely to contract salmonella, while people who used plastic cutting boards were twice as likely to contract salmonella. How regularly the plastic cutting boards were cleaned didn't make a difference.
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