Is the usage of blade with patina in the kitchen healty?

Y

yultuz

Joined
Dec 4, 2008
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I have a Opinel knife with carbon blade. When I peel an apple with it, a very bad smell occurs. I worry about that some toxic happens on fruits. Although I dry the blade, some rust occurs on the blade, but I can remove them by cleaning the blade.
My question is:
Are carbon blades healthy in kitchen usage? Do you experience this bad smell on the blade when using it on vegetables & fruits.
Thank you very much for your replies in advance.
Kind Regards,
 
I wouldn't use it.

Cutting mundane everyday things with carbon steel blades releases carbon monoxide into the atmosphere, and into your lungs.

Stay away, my friend.
 
I believe that the smell is the result of the acidic substances in your food interacting with the steel; basically rapid corrosion. From what I understand, this poses no health risk. I use several carbon steel knives in the kitchen, and have never had any problems.
 
I would think that, considering that most kitchen knives were made with carbon steel back in the day, that it shouldn't prove much of a health risk, if any. Sure, it might add a taste to whatever you're cooking, and the blade will develop a very nice patina that changes with every use, but carbon steel has always been a working steel meant for hard work. A little wipe down with mineral oil now and again, and a light touching up is all that's required. I've heard people saying how Old Hickory knives that have been handed down generations are some of the best kitchen knives around.
 
I'm not a doctor so take this for what you will.

Carbon and Iron aren't toxic and are actually nutritional. Your blood actually contains oxidized iron, which is why your blood is red (gross bonus fact: dead red blood cells contribute to the color of your poop too.) However, rust is TOXIC. Important distinction. Don't worry about the metallic smell unless the blade is rusty. Cast iron cookware is basically composed of the same material and is actually the most effective source of iron (heme iron.) Plant food contains mostly harder to absorb nonheme iron.

Like a well-seasoned cast iron pan, you can coat your knife with oil to reduce its reactivity to salt and acid. I suggest mineral oil for knifes. You can find it bottled and sold as a laxative, generally. It's a by-product of gasoline and something like 96% of it immediately passes through the body unaltered, with the rest following thereafter; a mere coating on a blade wont be enough to cause "evacuation" and it never goes rancid.

So long as you don't let the blade rust it might even be trivially safer than stainless steel---not that vanadium is anything to worry about. If you dislike the smell you could consider ceramic knives which are non-reactive but you have to send those away to be sharpened.
 
I don't worry about using carbon steel blades with food and I'm fine, health wise...at least for now :p.
 
They've used carbon steel blades for food since the iron age started and nobody has died from it !! Just wash and dry the blade after use . Don't bother polishing off the patina. For apple the major acid is malic acid which is reacting with the iron.
BTW with a cast iron pan when you season it you are forming a plastic [ polymerizing the oil] and the best oil to use is soy oil.
 
symphonyincminor said:
I wouldn't use it.

Cutting mundane everyday things with carbon steel blades releases carbon monoxide into the atmosphere, and into your lungs.

Stay away, my friend.
Click to expand...
Lol. You are going to have to explain that one. I want to see the chemical reactions as well as an explanation on how an odorless gas "smells bad".
 
symphonyincminor said:
I wouldn't use it.

Cutting mundane everyday things with carbon steel blades releases carbon monoxide into the atmosphere, and into your lungs.

Stay away, my friend.
Click to expand...

Tongue in cheek much?

Seriously, until about 1912 or thereabouts carbon steel knives were all we had. If you happen to get a little bit of iron transfer then it might help keep you from becoming anemic.

Don't worry about it.
 
It's a stone cold fact ...... everyone who uses carbon steel knives to prepare food will die someday!
 
Carbon blades have been used in kichens for years. Use a carbon blade, and a cast iron skillet, and you probably won't need iron supplements in your diet.
 
The patina protects the blade from rust. You can remove most of it with something like Barkeeper's Friend, but you shouldn't do that. It is a positive thing and doesn't affect the food at all. Not even a little. Rust is a different matter, not because it is unhealthy, but because it can color and flavor the food. If your patina hasn't developed enough to resist rust formation just rub the rust off with a cloth. In time the patina will resolve rusting. Here's my favorite slicer:

patina.jpg
 
When carbon steel knife is used with acidic foodstuff (apples, onions) you will get a reaction between the acids in the foodstuff and the iron (& minute traces of sulfur) in the steel. This releases hydrogen and also tiny amounts of hydrogen sulfide (which partially explains the smell) - at the same time you will get a deposit of iron oxides, tannins and various iron salts left on the surface of the blade (= patina). The small amounts of hydrogen sulfide released won't be in sufficient quantities to do any harm so don't worry about it.

Over time, the patina will help protect the blade and reduce the rate of further acidic attack. Many fans of carbon steel knives actually encourage a patina to form by using dilute phosphoric acid, apple cider vinegar or just leaving the blade sticking into an apple. Do NOT use hydrochloric acid (aka muriatic acid, brickies acid), nitric acid or sulfuric acid to do this as the salts formed are soluble and won't protect the blade.

However, some of the iron salts and oxides will also transfer to the fruit and if left in contact for too long will taint the taste of the fruit and cause it to 'yellow' more quickly. Apart from a metallic taste, this will not be harmful. Back in the days before stainless steel knives became available, sterling silver (or silver plated) fruit knives were used by 'the gentry' to avoid tainting the flavour of the fruit.

Opinel makes Carbon Steel and SS versions of most of their models as there is a diehard following for their C-S knives, so if it bothers you that much I suggest you get a SS version - but I think you'll find the 'smell' problem pretty much goes away if you let a patina form and don't try to polish it off
 
pvicenzi said:
Carbon blades have been used in kichens for years. Use a carbon blade, and a cast iron skillet, and you probably won't need iron supplements in your diet.
Click to expand...

Which is why everyone should have carbon steel kitchen knives! :D

I have a mild tendency towards anemia, but once I started using cast iron pans and carbon steel knives for food prep...suffice to say I haven't needed to take a supplement in years. ;)
 
Well, folk have covered pretty much all the points here... I didn't think rust was actually terribly bad for you (unless harbouring dirt and bacteria...), at least I hope not, having cooked a few meals in an unseasoned crock pot a few years back.

Another note on food acids reacting with carbon steel, I find that cutting pineapple makes the blade smell like homemade beef jerky curing in the oven. Maybe just the iron smelling like the iron content in the beef?
 
All your ancestors for thousands of years have used carbon steel blades in the kitchen. They're all dead. Obviously carbon steel blades are the cause. Don't use them! :rolleyes:
 
Thank you all so much. How about the vanadium? Carbon V steel of CS Twistmaster, isn't it toxic either?
 
My sharpest knife in and second most used knife in my kitchen (#1 is a Wustoff Santoku with kullens) is a French carbon steel 12" chef's knife with a beautiful patina going for it ;).
 
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