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Potatoes Stick to Knife Blade

Shel_B

By Shel_B
in Kitchen Consumer

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rotuts

rotuts

Posted
Posted

'''''   Rotus, that doesn't explain why spuds stick to a granton ''''

 

see the pic i posted above

 

'granton' portion is only on the lower part of the blade    the chef knife is smooth for a good bit above the grooves, the boning knife

 

much less so as it has less real estate above those grooves

 

a better stick-less knife would have groves top to bottom

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btbyrd

btbyrd

Posted
Posted

For?

Air borne potato starch granules?

 

For contradictions.

 

The claim that "potato starch that hasn't been cooked is not an adhesitive" contradicts your experience that there's a "white, starchy sticky substance on the knife blade that only spuds leave behind." It's not true that uncooked potato starch isn't sticky... it's just not as sticky as gelatinized starch.

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rotuts

rotuts

Posted
Posted

pickles stick.

 

i buy the kind  labeled  ' low in potato starch '

 

most of the effect is the water on the cut surface.  water fills in the imperfections making a very very smooth surface.

 

starch may help, just not so much w those pickles.

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Edward J

Edward J

Posted
Posted

For contradictions.

 

The claim that "potato starch that hasn't been cooked is not an adhesitive" contradicts your experience that there's a "white, starchy sticky substance on the knife blade that only spuds leave behind." It's not true that uncooked potato starch isn't sticky... it's just not as sticky as gelatinized starch.

 

 

You'll have to excuse my strange sense of humour.  Of course it's the potato starch on the knife blade causing the potato slices to stick.  I said that in my first post, and repeated in my second.  And if you read the first few posts on this thread you'll understand I'm not the first to  say this.

 

Rotus, of course pickle slices stick to a knife, as do most fruits and vegetables, and I acknowledge this in my posts. 

 

My point is, and what Shel B specifically asked, was why potatoes stick so stubbornly to the knife. 

 

O.k. no more attempts at humour, back to cooking........

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daveb

daveb

Posted
Posted (edited)

Don't know if it's been mentioned but a convex edge will reduce adhesions  

 

 

It's been mentioned.  But does not appear to be relevent.  It lacks the excitement of potatos in outer space with thousands of pounds of glass.  And olive oil.   And air pressure.

 

Next up:  Beets.  Is it the purple that makes them sticky?  Are they still sticky in the dark?

Edited by daveb (log)
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dcarch

dcarch

Posted
Posted
  1. Atmospheric pressure is universal. There is 50,000 lbs of pressure on you all the time. Your body also has 50,000 lbs of pressure to counter act the pressure. Until you are in an airplane, if the plane is not pressurized, you will be in trouble because your 50,000 lbs will push out everywhere. You will die instantly in outer space if you are not in a pressurized suite.

 

  1. It is so easy for everyone to understand suction cup works because of atmospheric pressure, but apparently it is difficult for everyone to accept that as long as you have two flat surfaces in close contact it is unavoidable that you have a suction cup situation. Suction cups can be made with any material, including potatoes. Potatoes do not make very good suction cups because of the texture is not very good, however a little water will help to seal leaking air into the “cup”. Still I will not try to walk up a skyscraper using potato suction cups.

 

  1. Now, wait just a minute, why is that if I wet the potato slice more, it comes off the blade much easier? Well, that is because you are talking about something entirely different. As I explained, thicker water is a very good lubricant, as with skiing or skating, which is entirely on water, not on ice. Also sliding sideways is entirely different than pulling out vertical, as defined by the law of physics, it take no work to move horizontally against a vertical force.

 

 The best thing of course is to utilize the sticking to your advantage.

 

 

dcarch

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AlaMoi

AlaMoi

Posted
Posted (edited)

that certainly explains why one squeezes a suction cup flat to the surface to eliminate the 'it's everywhere' atomospheric pressure inside the cup.

 

never noticed that my knife slices a potato into a cup shape - and actually never knew I was squeezing the slice against the blade to eliminate the air pocket.

 

need to pay closer attention, I suppose.

 

horse pucky.

Edited by AlaMoi (log)
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dcarch

dcarch

Posted
Posted

This seems to be the common problem, as these are very much obvious. This can be definitely avoide to a much extent by using proper knives. Drop Tip paring knife and Flip Tip paring are the options that can be tried for better results.

 

Very true, and was mentioned up thread by Scubado.

 

If you watch carefully, the video I linked shows how the food peels away from the blade with a single-bevel knife.

 

dcarch

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dcarch

dcarch

Posted
Posted

I came up with this idea for an experiment which you may be able to do, which will show you clearly the science of atmospheric pressure between two closely attached surface:

 

1. Find a 5" x 5" ( or any shape with about the same surface area) piece of flat plastic disk with a handle or metal disk that is flat with a handle.

 

2. get a thin plastic grocery bag and Scotch tape over the the entire plastic on a flat table, making sure there are no leaks. 

 

3. Use a straw to suck all the air out under the plastic and tape over the hole where you insert the straw.

 

4. It will be impossible for you to lift the disk without using over 350 lbs of force without breaking the plastic.

 

There is no water or potato starch between the surfaces to provide for adhesion.

 

dcarch

 

 

 

 

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dcarch

dcarch

Posted
Posted

I was not aware people are sucking the air out from between the potato slices.  I must be doing it wrong.

 

Yes, it is possible that you need to change the way you cut potatoes, your being able to get air in between the potato and blade where there is no space for air.

 

dcarch

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Edward J

Edward J

Posted
Posted

Yes, it is possible that you need to change the way you cut potatoes, your being able to get air in between the potato and blade where there is no space for air.

 

dcarch

  Well, if there's no space for air, how am going to get air in that space ?

 

Mysteries abound....

 

Maybe I could develop a knife with a hollow spine and little channels branching off  from that spine  exiting on the face of the knife.  Then, you hook up an aquarium pump to the port on the handle next to the usb port  and pump air through the knife....

 

NOT!~

 

You rinse the knife off after every 4 or 5 slices.  Not a major inconvenience, considering that peeled spuds should be kept underwater to prevent browning.

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dcarch

dcarch

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Posted

Maybe I could develop a knife with a hollow spine and little channels branching off  from that spine  exiting on the face of the knife.  Then, you hook up an aquarium pump to the port on the handle next to the usb port  and pump air through the knife....

 

 

Another possible way is to use sintering technology. You can make porous steel knife blades to avoid the buildup of atmospheric pressure.

 

Already, VG10, S30V, S90V steel are sintered powders for making quality knives.

 

If only you can make porous metal sanitary.

 

dcarch

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Edward J

Edward J

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Posted

Yes, it is possible that you need to change the way you cut potatoes, your being able to get air in between the potato and blade where there is no space for air.

 

dcarch

Yeah-butt,

 

With the above quote, you're implying that I need to change My way of cutting spuds in order to introduce air where there's no space for air in the first place.

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rotuts

rotuts

Posted
Posted

a time ago, CI on the show reviews chefs knives.  they had one I think from germany that had 3 - 4 rows of large dimples along the

 

whole width ( or height )  it was a fairly large chef's knive, say > 8 "

 

it was expensive    I cant find a ref to it.

 

they did say tomatoes and potatoes did not stick to it, But Cheepo Kimball balked at the price.

 

I wonder where that Demo lives now ?  it at the time was a very unique looking knive

 

sorry I cant find it to further fuel the Potato Fire.

 

BTW here is a ref to some of the fine knives I own :

 

 

http://www.detectamet.com/professional-knives-scallop-edged.htm

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dcarch

dcarch

Posted
Posted

 

I don't have that kind of knife. But I think that design can make cutting certain food better, but others worst. 

 

In any case, in the world of tools for cooking, there are plenty of products which make use of some scientific concepts to sell unscientific goods to the public.

 

For instance, the same advertisement, "Each Glestain knife comes with a balanced, handle ". How do you have the same handle balanced for different length blades?

 

dcarch

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AlaMoi

AlaMoi

Posted
Posted

I have a mandoline.

the blade comes out for cleaning. 

the blade is about two inches wide.

the blade is flat - same thickness over its entire width (except for the cutting edge)

I slice potatores on the mandoline.

 

all the slices fall cleanly to the board underneath.

slices do not stick to the mandoline.

 

apparently it injects air somehow.

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dcarch

dcarch

Posted
Posted

I have a mandoline.

the blade comes out for cleaning. 

the blade is about two inches wide.

the blade is flat - same thickness over its entire width (except for the cutting edge)

I slice potatores on the mandoline.

 

all the slices fall cleanly to the board underneath.

slices do not stick to the mandoline.

 

apparently it injects air somehow.

 

Not really. If you read what I have pointed out several times, and if you read Physics 101, slicing is horizontal work, it take no horizontal force to work against vertical force (atmospheric pressure).

 

I am more than happy to keep explaining.

 

dcarch

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dcarch

dcarch

Posted
Posted

"it take no horizontal force to work against vertical force (atmospheric pressure)."

 

 

you can stop now.  not sure how to put this politely, but you have no idea of what you're talking about.

 

Thank you for being polite.

 

dcarch

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