I like my cutting boards that can be sterilized in a microwave

Originally published at: http://boingboing.net/2017/05/06/i-like-my-cutting-boards-that.html


“the surface of the mats will show cut marks”

Which means they need to be replaced. That sort of scarring on non-wood cutting boards will capture dirt, and various nastiness. Which means any time you aren’t sterilizing them or sanitizing them with bleach they can harbor bacteria and spread it to multiple foods (and unwashed produce is currently the #1 source for food born illness outbreaks, rather than raw meat).


Is there an argument for wood being more sanitary?

How do you know they’re sterile?

@gellfex: I read a study long ago that found, counter-revolutionary, wood retains fewer bacteria, but there’s no way I could give a citation.

From what I recall wood under actual testing is more sanitary. As in go swab a bunch of cutting boards, and the wood will be the cleaner one. The explanation is apparently down to wood being “self healing” in a way. Moisture makes the wood swell, closing knife scaring as tightly as if they weren’t ever there in the first place. Leaving bacteria and dirt no where to hide. So you can sanitize the thing by simply wiping the surface with bleach or another sanitizer. Maintain that wood cutting board properly, by oiling it. And the whole surface of the wood gets impregnated with the oil. Which will not only provide the liquid needed to close up the knife scars. But will render the entire surface water repellent and impregnable. Meaning you don’t need to worry about infectious juices and animal fat soaking in and spoiling later.

The plastic and rubber ones are fine. Nicely impenetrable and sanitize-able surface. Until they get knife marks or other moderately deep wear on them. The plastic doesn’t close up. Leaving very tight, impossible to clean, crevices for bacteria and mold to grow in. So at that point thin ones need to be discarded. And thick ones need to be sanded down.

I’m curious about that too. Microwaves work by exciting the water molecules in things. They’ll heat up other stuff (say metal) without any water present. But I’d be really curious about whether the microwave can hit the appropriate temps and hold them there long enough without a dish of water to effectively steam sterilize the thing (which takes a while). Microwaves also heat unevenly. So you could very well be sterilizing some of the board. But leaving some just hanging in bacteria breeding sweet spots. Making the knife gouges all the more dangerous.

There are a bunch of them out there. The one I usually link to seems to be down though. Easy enough to find detail just by googling it. Its become one of those “fun fact” sort of things the last few years.


In Michael Pollan’s book Cooked, he does a long piece about how making cheese in a scuzzy old wooden bucket was more sanitary than a stainless vat because of it’s established “good” bacteria colonies keeping the bad at bay.

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Apparently microwave ovens can be used to sterilize stuff.

Our non-wood cutting boards have cut-marks galore. Automatic dishwasher fluid has bleach, and I go that way, but before doing so I use scotch-brite to scrub the surfaces with soapy hot water to help loosen things up and remove any grease that might want to retain anything. So, a soapy scrub pre-clean, then the washer.

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Note it specifies soaking wet stuff.

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Yes, I noticed that. This mat claims to be made from an antimicrobial material, or infused with some such, but that is more often than not marketing bs.

arg. Pollan has gone kind of whole hog on the naturalistic fallacy thing hasn’t he? To an extent he isn’t wrong. Establishing a strong colony of beneficial bacteria or micro organisms (like those used in cheese making) under appropriately sanitary conditions will prevent later infection with harmful microorganisms. That’s the central mechanic in fermented preservation techniques.

BUT. A scuzzy old wooden bucket is not like a wooden cutting board. A wooden cutting board is a solid plank of glued together sections of wood. There are no appreciably gaps in the thing. And the small, shallow gaps caused by knives (and other use) are well within the bounds of the expansion and contraction of wood’s ability to close them up.

A bucket has fittings. And joints. Those are gaps far too deep and far too wide to ever close and seal from the natural action of wood in the presence of moisture or fat. Those gaps provide places that harbor micro organisms. Allowing them to breed and persist despite aggressive cleaning. That was good in old school cheese, beer, and other preserving. Before we could isolate and control the microscopic bastards that make it all work you’re traditional wooden tools would inoculate your cheese and beer with the necessary critters.

The problem is that those same features mean any negative infection in that bucket can not be prevented or eliminated. So once the bucket is contaminated (and it will be, you can’t sterilize wood). Then you end up contaminating everything that touches the bucket.

The exact same “good bacteria” keeping things at bay dynamic happens in the stainless steel vat. Except the stainless steel vat can be sterilized meaning you can prevent or remove any contamination. Then you inoculate with useful bugs. And keep everything sanitary till they have a toe hold. If wooden buckets, lack of sanitation control and lack of pasteurization in the old days was better and safer than stainless tanks and actual control (and understanding) then Polan should explain the vast number of deaths caused by dairy products before the advent of modern sanitation and production processes.

The major difference is control. With the wooden bucket its all up to chance. You have no ability to control anything that’s going on. With the stainless, bleach, and packets of bacteria/yeast you are completely in control.

That stuff is not getting into the near microscopic deep parts of the cut marks. That’d be where the bacteria is hiding. Sand them down to remove the scratches or replace them. The heat from the dishwasher will sanitize the surface of the boards. And on a long enough cycle will penetrate deep enough to sanitize the scratches. But to control that situation with heat you need to be sanitizing or sterilizing the boards before every time you use them. Not after. Heat sanitized or not there’s still crud trapped down there, and stored in your cabinet that crud can grow friends.

Unused that crud is largely harmless (till mildew or mold shows up, which has happened to me before). But if you don’t kill it before food touches the board you might end up contaminating something.

Or you can sand them down. And avoid the whole situation.

Honestly the risk of such things is low. But if you’re at all concerned about contamination on your cutting boards then it pays to understand the dynamics of sanitizing something.


I appreciate your concern. And I understand the dynamics of cleaning to the extent that the cleaning method we employ (and how we cook, also!) has not resulted in food poisoning at home.

Mmmm, whole hog BBQ, loved that chapter! Seriously, have you read it? He relates the whole story of how a nun in a monastery in CT got a PhD in microbiology to prove this theory, and legally be about to make her traditional cheese. Controlled studies showed higher incidence of bugs, Listeria I think, in the stainless than the scuzzy bucket.

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And it probably won’t. Though it would be more likely to do so than a simple wooden cutting board. The bigger issue is that once something comes to life in that plastic. You aren’t getting rid of it. I’ve had a few plastic boards (especially thinner ones that can’t be sanded) that I was lax with come down with mildew. Its kind of gross and you can punch it back with bleach or mildew remover. But its coming back. And its tends to spread to the cabinet wood and other kitchen tools.

Other than that the board will be significantly easier to clean if you sand the scratches out. The dishwasher on its own will do it for a smooth board (usually). No scotch pad or scrubbing needed.

I do a bit of home brew and the same dynamic is a big problem with plastic fermenters, tools and bottling buckets. Once you scratch the material. Or something starts growing in the fittings. You can end up with an infection from beer ruining micro-organisms you’ll never get rid of. And your plastic tools need to go in the trash.

Until some of the listeria gets a toe hold on her bucket. Or some one properly sterilizes the stainless steel. Polan can cherry pick heart warming stories all he likes. A strong colony of useful bacteria can keep listeria (the big one with dairy) at bay. But once it fails the bucket is done for and you have no way of knowing. You’ll see infections in the stainless too, but those infections can be removed. You can know the stainless steel is safe. If you sanitize/sterilize before every use. Lax sanitation practice is one of the only problems there. The better metric on this is number of illness caused by both production method. And frankly if you look at what our colons looked like before the advent of real sanitation regulations on the dairy industry… Well I wouldn’t be trusting the bucket.

Traditionally the bucket was a great way to keep your unique colony of bacteria and yeasts going, and inoculate each batch with the same stuff. But we’ve got far better ways of doing that these days.

That’s you’re major difference.Infection with harmful bacteria will happen in a production environment. The x factor is in control. You can prevent it or reverse it with the stainless. You can’t with the bucket.

Sanitation requirements for cheese making, curing, and fermenting are much stricter than for general cooking. So it doesn’t neccisarily bear on the whole cutting board thing anyway. You don’t want an active colony of fermenting bacteria and yeasts on your cutting board. Because you don’t want your fresh food to be pickled. The time lines wouldn’t allow it anyway. The “good” colony also contains bad things (at lower levels) and the conditions of what’s contacting it may be more amenable to the bad over the good. And the vast majority of what hits that board is going to be cooked. Which will kill whatevers on the food anyways.

Some years ago we started with THIN plastic boards, but the first couple eventually got misshaped (from the dishwasher heat). Our 1/2" thick boards are holding up nicely (so far).

Now I’m guessing that a tempered glass cutting (not chopping!) board would be the ideal, being so smooth. That could be the way to go for someone who doesn’t mind having to sharpen their knives more often.

No, this is not correct, putting a plastic cutting board into the dishwasher certainly sanitizes it, cut marks and all, especially if it has an effective dry cycle. The narrative about plastic cutting boards harboring bacteria goes back to the work of Dean Cliver at the UC-Davis food safety lab, it started as a project on how to make wood cutting boards as safe as plastic for cutting chicken etc. What Cliver and his colleagues found was that knife-scarred plastic cutting boards were hard to properly clean manually, but that dishwashing did in fact clean them effectively. They also found that microwaving effectively disinfected wooden cutting boards (but apparently not plastic ones).

Much of the common wisdom in the foodie community about plastic vs. wooden cutting boards seems to be the result of improper reporting (and repeating) from these actual findings by Cliver et al., perhaps because of not looking at the actual publications (two articles in J. Food Protect., Vol… 57, 1994) they relied on summary press reports.


Yes and no. Glass still scratches. But its easier to clean. But do not get a glass cutting board. It is murder on your knives.

Other than that sanding down your boards renders them easier to clean. Better to use and all round nicer. I’m sure they’re holding up nice. But sanding the things down is just basic maintenance. Like oiling the wooden board. These things aren’t life time purchases. They need occasional replacement. Sanding them down gives you a longer period of use.

Right like I said. Heat sanitation. Which may not neccisarily remove gunk, though a better dishwasher certainly might. But the crevices still remain. I’ve had deeply dirty, or as I said mildew infested boards, before. The handy thing about dark grunge and mildew is they are visible. Run through a dishwasher and the dirt in the deep scars remains. The mildew likewise remained in the deep recesses of the cuts, whence it spread its love to the rest of the board again. And I used typical dishwasher detergent. Run that mildew board through a deep clean or sanitize cycle (Since my dishwasher had that) and the mildew gets killed. But the scars are still there. Where they can pick up dirt. Bacteria. And mildew again.

Lets be clear we’re talking about extreme cases here. Which is why mildew problems is kind of my practical worst case scenario. I’ve routinely gone without even washing my cutting boards (including plastic ones) after non-meat use. And noone in my house has gotten sick or died. The mildew issue damaged some cabinets in an apartment I was renting (I still got my security deposit back). Properly maintained (or even laxly maintained) plastic is fine. Properly maintained (or even laxly maintained) wood is also fine. For meat, fish, veg, people whatever.

Part of my focus on this comes from working in restaurants. Your sanitation controls there are a lot more rigorous. More people pushing more food means more opportunity for contamination and illness outbreaks. Of much larger scale. Scarred up or worn plastic cutting boards are a health code violation in most parts. And new, unscared. Or freshly sanded plastic boards are just more functional than one that’s all gouged up. But if you are concerned about sanitation on cutting boards you might as well do it properly.

Even if the ‘antimicrobial’ material claim is true.

Do you really want some chemical agent embedded in plastic that stays in the mat…and survives washing and microwave…and is still active to kill bacteria after all that abuse?

Yeah…give me a wooden cutting board.

Like silver? Which is perfectly safe to consume (for the most part) and is one of the more common anti-microbial compounds found in this sort of thing. Shit I’ve got anti-microbial socks with silver thread in them.

Salt is anti-microbial. As is honey. I think copper too. And I seem to remember something about stainless steel inhibiting the spread of bacteria.


The ratio of BB post to shameless shill is like 50/50 now.

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