# Carbon knives and taste



## Dhoff (Feb 13, 2019)

Is IT true carbon knives can make food, especially fruit, taste og metal?


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## tgfencer (Feb 13, 2019)

Never experienced it. Certainly wouldn't happen on a knife with patina, I'd of thought, given the reactivity of the steel would be minimized. But I am no scientist.


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## Dhoff (Feb 13, 2019)

Im happy to hear that. I Saw a lot og threads on other forums stating problems


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## podzap (Feb 13, 2019)

Maybe if you left the carbon knife standing for a day inside a pot of acidic food. Brief contact, such as slicing a lemon, is not long enough to cause any reaction. Of course, if you don't actually wash your knives after use then they can taste like anything.

"*Believe Nothing You Hear*, and Only One *Half* That *You* See" - Edgar Allen Poe


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## HRC_64 (Feb 13, 2019)

yes its true...problem is worse with reactive steels with more impurities

In japan they have e thing called "fruit knife" which is a stainless steel petty...
for this very reason IIRC.

the acids in the fruit can react with sulfur for example, but even regular carbon steels
depending on acidity vs delicateness of the fruit.


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## HRC_64 (Feb 13, 2019)

Some people just cannot taste very well either... 

People will follow recipes that say "infuse the olive oil with crushed garlic"
and then argue cutting endless aromatics on a wood board doesn't transfer flavours

not understandint that the board is coated itself in oil (mineral oil) 
and will absorb the flavours just like the recipe 

(so this is why pastry chef won't let you prep on her boards)


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## Ivang (Feb 13, 2019)

Yup, they can react very strong to certain ingredients

Onions will turn blue and smell like sulfur, mango and avocado will turn black, and so on. Not all carbon knives react the same, in my experience, iron clad knives are the worst.


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## Dhoff (Feb 13, 2019)

So, a Munetoshi I had my heart set on for future purchase is a bad choice when it will also be used for acidic fruit?


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## Lars (Feb 13, 2019)

Carbon makes my food taste awesome.

Lars


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## parbaked (Feb 13, 2019)

Carbon knives are evidence that you have good taste...


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## HRC_64 (Feb 13, 2019)

Dhoff said:


> So, a Munetoshi I had my heart set on for future purchase is a bad choice when it will also be used for acidic fruit?



Yes, the general rule is don't buy a iron clad knife for a 'fruit knife' ...


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## minibatataman (Feb 13, 2019)

I have the munetoshi 240mm
I use it and doesn't cause any discoloration as long as you're frequently wiping it. Sometimes im too lazy and then I do notice the onions discoloring, but it didn't affect the taste.


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## mille162 (Feb 20, 2019)

If you’re eating off the knife, yes: http://www.ediblegeography.com/sensoaesthetic-spoons/


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## Dhoff (Feb 20, 2019)

Opinions Seem quite divided


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## mille162 (Feb 20, 2019)

Dhoff said:


> Opinions Seem quite divided



Pretty easy to test yourself at home...


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## Dhoff (Feb 20, 2019)

Yes and No, i do not yet own a carbon


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## Ivang (Feb 20, 2019)

It really isn't a matter of opinion. Wether the fact that carbon steel reacts to food and vice versa matters to you enough to be worth the trade offs, that is a matter of opinion


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## stringer (Feb 20, 2019)

Simple carbon knives without patina 
(freshly ground, thinned, sharpened, polished, etc.) will turn yellow onions black and make everything in your fridge smell like sulfur for at least a month. Don't ask me how I know.


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## Dhoff (Feb 20, 2019)

Well, some say food taste Will be affected. Some say it Will not. To me, that makes it seems There are different opinions


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## Michi (Feb 20, 2019)

I can taste the metal when cutting mild fruit, such as apple and pear, with a carbon steel knife. For fatty foods, such as cold cuts, jerky, and similar, I don't perceive any difference.

The article about the different metal spoons was interesting, thanks for that! It mentions Riedel glasses for different varieties of wine. I've been to two Riedel tastings where people get a chance to test this for themselves. It is remarkable how much the size and shape of a glass influences taste. You can pour wine from glass to glass or put a bit of the wine into each glass, and then see how the identical wine tastes differently depending on the glass.

It's quite amazing, especially with red wines. Take a sip from one glass, and you might have an average quite flat and boring wine, not very interesting at all. Pour the contents into a glass with a different shape, and the same wine tastes not only a little bit different, but a lot different and really springs to live. So much so that, in a blind tasting, I would swear that it is a completely different wine. Pour it back into the original glass, and it's dead again.

What this shows mainly is how important the sense of smell is when tasting things. Much of the differences in the wine tasting from different glasses are due to how volatiles are released from the wine. A secondary effect is how the shape of the glass changes which part of the tongue comes in contact with it first; different areas of the tongue have receptors for different tastes, so where the wine goes in the mouth changes the way it tastes.


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## PC315 (Feb 20, 2019)

So do most people here use stainless steel to cut acidic fruits and onions?


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## stringer (Feb 20, 2019)

A knife with a well established patina shouldn't cause off odors or tastes. You just have to be careful after you sharpen. Cutting citrus with carbon does make the edge deteriorate faster. So that might be a reason to prefer stainless or semistainless for certain tasks.


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## Paraffin (Feb 20, 2019)

Dhoff said:


> Well, some say food taste Will be affected. Some say it Will not. To me, that makes it seems There are different opinions



It's not just different opinions, it's that different knives may react in different ways, form patinas differently, and so on. We're not all using the same knives, or using them on the same food product. Some people enjoy seeing a nice patina (like me), others may periodically scrub off the patina leaving a more reactive surface.

I have never had a bad taste experience with my carbon knives. I have never seen a color reaction in food either, with ONE exception, and that was when slicing a big red cabbage with my carbon nakiri. It caused an immediate change in the cut slices, turning the cut edge blue, with blue liquid released in the cut and covering the knife. Very weird. As it turns out, red cabbages (and some other red veggies) are very sensitive to Ph, and will change to that blue color in contact with an alkaline substance. I guess that particular knife patina was a little alkaline for some reason. So I switch to a stainless nakiri for red cabbage. It's the only time I've noticed a reaction with my carbon knives. But those may be different from _your_ carbon knives and food products.

I do use a stainless petty knife for slicing large amounts of lemons, limes, or oranges, but that's aimed at preserving sharpness. Prolonged contact with acid may slightly affect the blade edge. It may be overkill for the amount of acidic food I ever cut in one go, but it's a good excuse to own another specialized knife!


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## Dhoff (Feb 20, 2019)

Paraffin said:


> It's not just different opinions, it's that different knives may react in different ways, form patinas differently, and so on. We're not all using the same knives, or using them on the same food product. Some people enjoy seeing a nice patina (like me), others may periodically scrub off the patina leaving a more reactive surface.
> 
> I have never had a bad taste experience with my carbon knives. I have never seen a color reaction in food either, with ONE exception, and that was when slicing a big red cabbage with my carbon nakiri. It caused an immediate change in the cut slices, turning the cut edge blue, with blue liquid released in the cut and covering the knife. Very weird. As it turns out, red cabbages (and some other red veggies) are very sensitive to Ph, and will change to that blue color in contact with an alkaline substance. I guess that particular knife patina was a little alkaline for some reason. So I switch to a stainless nakiri for red cabbage. It's the only time I've noticed a reaction with my carbon knives. But those may be different from _your_ carbon knives and food products.
> 
> I do use a stainless petty knife for slicing large amounts of lemons, limes, or oranges, but that's aimed at preserving sharpness. Prolonged contact with acid may slightly affect the blade edge. It may be overkill for the amount of acidic food I ever cut in one go, but it's a good excuse to own another specialized knife!



Nice post! Appreciated


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## Michi (Feb 20, 2019)

Paraffin said:


> It's not just different opinions, it's that different knives may react in different ways, form patinas differently, and so on.


In addition, not everyone's sense of taste is the same either.


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## Kippington (Feb 20, 2019)

I've seen @Marek07 correctly point out apple slices which had been cut with a carbon steel knife over a stainless one in a blind test. I personally can't tell the difference.


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## doomtop (Feb 21, 2019)

I've often used carbon knives for vegetable prep, including onions, and haven't noticed an effect on taste. I think I have a decent ability to isolate and differentiate.

That said, I also always use stainless to cut citrus, but not because I think it affects the taste.


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## Luftmensch (Feb 21, 2019)

Dhoff said:


> Is IT true carbon knives can make food, especially fruit, *taste* og metal?



I can't add much more to what has been said. Personally, I have _not_ noticed a taste difference. But that sulphurous aroma from cutting onions on freshly polished steel is distinctive. You can see the onion tissue being stained. The reason I suspect i can't taste a difference is because meals end up being a mix of many ingredients. I also always eat my fruit... well... like an apple!



Dhoff said:


> Well, some say food taste Will be affected. Some say it Will not. To me, that makes it seems There are different opinions



@Michi's post on tasting is true ([email protected], maybe you should have become a sommelier!). Smell plays a large role. Some people might have anosmia. They might be a pack-a-day smokers. They might not be very mindful about what is in their mouth. There are also genetic causes for differences in perceived taste. Age....


But I am going to go with @parbaked on this one:



parbaked said:


> Carbon knives are evidence that you have good taste...


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## PC315 (Feb 21, 2019)

Btw, apologies for the n00b question, I assume for the folks that do taste something with carbon knives, it's noticeable with all of them regardless of white/blue/cladding/etc right?

Any other food folks avoid cutting with carbon knives?


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## Luftmensch (Feb 21, 2019)

PC315 said:


> Btw, apologies for the n00b question, I assume for the folks that do taste something with carbon knives, it's noticeable with all of them regardless of white/blue/cladding/etc right?



In short; no. It is one of those "it depends" answers. Like @Paraffin said:



Paraffin said:


> it's that different knives may react in different ways, form patinas differently, and so on



Some knives are more reactive than others. At this point my observation would be that cladding that has the biggest impact in this area (after all it has the largest surface area). People don't tend to get so tribal about the cladding material the same way they do when it comes to core material, so exact compositions for the cladding arent discussed much, if at all.

I only have two different carbon steel knives and I would say they are about the same in reactivity. Certainly after each has accrued a patina


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## PC315 (Feb 21, 2019)

Apologies to OP if I ended up hijacking the thread. About to get some Watanabe KU knives (nakiri and a petite) to cut fruits and vegetables so was curious what people's experiences were


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## Dhoff (Feb 21, 2019)

Np i enjoy the discussion


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## Luftmensch (Feb 21, 2019)

PC315 said:


> Watanabe KU knives



In the theme of "it depends".... a KU knife will appear to be less reactive in the sense that there is less surface area of carbon steel exposed to food. Most of the surface area of the knife is relatively inert KU. Only the blade road will be reactive. 

Watanabe has a fine reputation. I am sure you will enjoy them very much. I'll leave others to comment on their experience with them with regards to reactivity.


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## SeattleBen (Feb 21, 2019)

Not backed up by science but I think there's a quality of steel that impacts this as well. I can taste the knife on a freshly sharpened CCK but not as much on nicer steels.


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## parbaked (Feb 21, 2019)

PC315 said:


> About to get some Watanabe KU knives (nakiri and a petite) to cut fruits and vegetables so was curious what people's experiences were



If those are the professional series Watanabe knives, the blades are stainless clad blue steel. 
Reactivity shouldn't be a problem.


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