Vegetable slicing for stocks etc

Since I did a number of stocks this weekend and a red wine sauce, I had allot of veggies to slice up (onions, carrots leeks etc). While slicing the carrots on a mandoline, I couldn't help but to wonder, does it matter in which direction?. I know that we need to chop/slice the food into tiny pieces or or thin slices and the mandoline is great for this. But, if we take a carrot for instance, choose two the same size (yes I did this) and hold the carrot vertically and count the passes, there was approximately 110. Now if I hold the carrot horizontally, or parallel to the mandoline, there were about 20 passes...that's allot of time saved..when one is doing allot of stocks etc. What I wonder however is will this affect the overall flavor release into the stock? If we take the carrot (since it's the example here), we know the core is removed for things like carrot soup precisely because of the flavor it imparts.......but if we expose it more purely for a stock (like in the manner mentioned) will it matter? Or for any other vegetable?

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Daniel_Levy_59584

it seems to me that it shouldnt make a big difference which way you slice it - except that if you slice it vertically youll have a little more surface area exposed since its more pieces. easy fix for that would be to just lay out the horizontal slices and cut with a knife a bit.

Brandon_Byrd_40557

I was wondering the same thing today, as I was making the vegetable stock from MC@H. While I don't mind slicing onions on the mandoline, I hate, hate, HATE, slicing carrots. Doing it with a chef's knife is really tiring, even if you're just going through a kilo of them. Maybe my aversion to carrots on the mandoline stems from the fact that I sliced off the end of my thumb doing it a year or so ago. So when it came time to do it for stock today, I did a coarse grate on the carrots using my Cuisinart (so they came out looking like salad bar style grated carrots, thin and about an inch long). It was much faster and easier to do it this way, but I did have the thought that processing the carrots would make the broth come out overly carrot-y. If I had a RobotCoupe, I'd use that to dice carrots instead and wouldn't worry about it... not that I really worried about it that much today when making stock. But I'd still like to know if there's a significant difference in extraction/flavor when using different slicing techniques if you're going to cook SV over several hours. I doubt it, but that's purely intuitive and so I don't have any idea about whether or not it's really true.

Brendan_Lee_56950

I believe there was discussion about this when the CS team did the demi-glace recipe, the concern AFAIK was OVER extraction, namely things may get bitter if you grind or slice too thinly. My food processor has a disk attachment that makes some decently thin discs so I can run nearly anything in the hard root veg family through their without a problem.

tshewman

In the example I can't see how over-extraction (as it were) would be an issue when the thickness would literally be the same. The slices of carro would simply be 3-4 times longer than if we sliced on a perpendicular. So in theory it "should be the same (or very very close), but I thought I might be missing something (and still do). So far, I say carrots sliced that way used in a pressure cooker to create a red wine glaze (and cook oxtail-ironically the glaze is for tomorrow but serve the oxtail last evening) had no negative flavor effect.

GaryT_92514

If the thickness of the transverse or longitudinally cut slices are the same, the the total surface area of the slices will be the same. This is because, to a first approximation, the volume of the carrot will be the sum (across pieces) of the product of surface area x slice thickness. Because the carrot volume is fixed, and if the slice thickness is fixed (by a mandolin), then the surface area has to be the same. If thickness is allowed to vary (for example you can't be bothered making as many transverse cuts) then surface area will be modified accordingly. This can be seen in the extreme case of only making one cut - the surface area exposed will be much less for a single transverse cut than for a single longitudinal cut.

tshewman

I agree Gary, however, since different components may vary depending on the location of the slice (e.g. I core carrots for carrot soup), would the more immediate longitudinal exposure impart a different flavor. In theory, I would respectfully submit possibly. Practically, I have yet to taste that difference.

GaryT_92514

'Practically' usually gets in the way of 'theoretically' Todd

I'm impressed you core the carrots for the soup though. I keep meaning to make that effort!

Daniel_Levy_59584

@garyt

its hard to say whether the surface area would be the same without actually doing the calculations, which would likely involve calculus to be exact due to the roundness of the carrot and tapering end to end. keeping the thickness the same doesnt mean the surface areas will be the same, since the shapes will be different.

for example, take a basic rectangular box, say 5 mm x 5 mm x 10 mm. if we make 1 mm thick slices, slicing it the short way gives us 10 5x5x1 shapes for a total surface area of 700 mm^2. if we slice it the long way, we get 5 10x5x1 shapes for a total surface area of 650 mm^2. this difference is because each of the larger shapes is basically two of the smaller ones joined together, so you lose the surface area of where its joined.

a carrot is round, though, so that complicates things a bit. we can approximate the calculation, though, by assuming each long slice to be a regular shape rather than the awkward trapezoidish cross-section it actually has. less assume a rod of 5mm diameter and 10 mm length, again cut to 1 mm thick. the calculation cutting the short way is straightforward, we have 10 rounds of 1 mm thickness and diameter 5 mm, so 10 * ( ( 2 * ( pi * 2.5^2 ) + ( 2 * pi * 2.5) ). which comes out to about 550 mm^2.

for the long cuts, we will have 5 pieces, each of thickness 1 mm and varying widths. for an approximation, we'll assume a width of 5 mm for the middle one. the 2 next to that one will vary from about 5 mm wide on one side to lets just say 3 mm on the other, so we'll average it to 4 mm. for the two curved sides, we have to add some area to account for the slant, so we'll call that 1.4 mm wide. the outer two pieces will have a side of 3 mm and an arc on the other side. lets just assume the arced side to have about a 3.5 mm width. plus the small ends, averaged to 1.5 mm wide. these are gross approximations, but itll have to do for now. so the middle piece comes out to 130 mm^2. the next two pieces each come to 116 mm^2 using the approximations, and the two outer pieces each come to 68 mm^2. which gives a total of 498 mm^2. so again, it comes out smaller for the longer pieces, although how much of that is due to the approximations is hard to say.

edit:

lol, actually i just realized while trying to google a formula for this that theres an easier way to make the comparison. lets make the diameter 2 mm so we only make one cut the long way. its a simple calculation then. the short way is still calculated the same way - 10 * ( ( 2 * ( pi * 1^2 ) + ( 2 * pi * 1) ). which comes to 125.6 mm^2. for the long cut, itll be the surface area of the rod plus the two cross sections. this comes to 2 * ( pi * 1^2 ) + 10 * ( 2 * pi * 1) + 2 * (10 * 2 ). which comes to about 109.1 mm^2. so again, slightly smaller, this time for certain.