Soup Skimming

[weinoo]

I skim chicken stock, if I make it on the stove top the old-fashioned way. I guess I skim veal stock too.

But, I don't skim any other soups and some of them definitely look scummy at the start of the cooking process. Like, for instance, the split pea soup I have on the stove now.

Do you skim?

[Pam R]

Yep. Of course!

Skim soups with meat/bones. Don't skim vegetarian soups (like bean soups with no animal products). Those look less scummy to me and more foamy, which I always assumed was starches being released.

[takadi]

Scum is just coagulated blood and myoglobin...imparts a slight livery taste to the stock, which is desired for me for some instances (like sauces or demi)

[huiray]

If I am making soups/stocks w/ bones (w/ or w/o added meat) I frequently parboil the bones first (beef or pork bones especially) for a short while (typically, bones into hot water, boil for a few minutes) then fish the bones out, if doing it in batches, and wash the bones under a running tap. Or dump the pot + scummy water + bones into the sink and wash the bones under the tap. The "cleaned" bones go into a fresh pot of clean cold water in a clean pot and the stock proper is then made. This is a common technique in many E/SE Asian cuisines. In Chinese/Cantonese this is called "fei sui" (飛水; "flying (through) water"). It removes most of the blood, various stuff, myoglobin, impurities etc; and stuck-on congealed bits are scrubbed off/picked off under the running tap as one washes the bones. Stock made with cleaned bones has a much "cleaner" smell (and is clearer) than stock made with unwashed/uncleaned bones - with the attendant blood/junk smell. I will sometimes also do this "fei sui" thing with hunks of meat that go into the stocks.

With chicken bones/carcasses I tend not to do the "fei sui" treatment unless there is really lots of gunk - a good wash under the tap will often suffice. In any case I will still skim the stock even if I start with cleaned/parboiled bones, as there will still be some stuff left. I tend not to do the "fei sui" treatment with pork spare ribs (e.g. when I make Bak Kut Teh) but will do so sometimes, depends on my mood and the bloodiness of the ribs...skimming will be done as needed.

Vegetable soups or stocks - I seldom need to do any skimming.

I once made Phở at a friend's house where I did the "fei sui" treatment of the beef bones** - and hung on to the scummy parboiling water. I asked my friend, who had never done this parboiling treatment of any sort of bones before for stock (and had never heard of doing this for stocks before), to smell the parboiling water and the developing stock (in a fresh pot) with the cleaned bones - and the look on her face was (as the Mastercard ads say)...Priceless. :-)

** My understanding is that most restaurants that serve phở will also do this parboiling treatment of the bones.

[Hassouni]

I do exactly what huiray described, and it results in minimal skimming necessary

[weinoo]

I've definitely used that technique in the past. I'm sure the first place I read about it was in one of my earliest Chinese cookbooks.

[Paul Bacino]

With ckin..I'll do pressure cooking, stain every thing,rid the bones and stuff, chinois the liquid into a pot, let it chill over night, then I get schmaltz, and the top cooled gel stock is usually clear as the sediment settles

[huiray]

Yes, that's right about the schmaltz - I forgot to mention it.

When I skim my stocks (at the beginning and while simmering) I frequently use a medium-sized (~6" diameter x ~1½" "deep") fine-meshed metal sieve with a handle at 45º to the "bowl". This sieve usefully lets me "press down" the stuff in the pot while scooping scum + stock + oil into the "bowl". I leave on all fat on my chicken bones/frames/etc so when I sieve out the foam, scum etc I also let the accumulating liquid chicken fat drip back through into the stock. At the end I spoon off the fat (still hot/warm stock; I very rarely refrigerate it at that point) and decide how much of it to leave with the stock/broth. Yes, like Paul Bacino and lots of other folks this chicken fat/schmaltz gets used in other ways - not always, though...

Ditto with other types of bones, I leave the fat on - or most of it, if there is really just too much of it - and skim while letting the oil stay behind while the stock is simmering. If there *is* just too much fat then some gets removed during the simmering.

With pork bone stock/broth I should clarify that different bones and different intentions give rise to either clear stocks or very milky stocks. Simmering (cleaned) knuckle/shin pork bones with plenty of cartilage caps and collagen/tendon bits and plenty of marrow (preferably also w/ some meat still attached) for a very long time (I have done it for 8-9 hours and sometimes w/ an overnight rest and reheating again before separating the bones from the stock) gives a heavily gelatinous *and* milky stock - YUM! - which I use for things like a daikon + ground pork meatballs + vast quantities of ground white pepper soup. :-) Milky pork stock is also common for "real" bowls of ramen, of course.

[MikeHartnett]

I skim as little as possible. Sometimes, it's clearly necessary. Sometimes it isn't. If I can get away with not doing it, I don't.

[TheCulinaryLibrary]

When you boil stock or soup some of the proteins denature and if not skimmed will sit in bubbles on the surface in a cloudy grey mass and eventually breakdown and disperse creating a cloudy soup with speckles. Skimming gives a clearer, cleaner look and better visual appeal. If you object to skimming, try eating a few spoonfuls and see it that changes your mind.

[OliverB]

if it's really scummy and foamy yes, otherwise I don't bother. I don't need super clear stocks for my purposes, I leave that to fine dinging out. Nowadays I almost always make it in the PC, though even there I'd also do the short preboil/clean with big bones.

[Shel_B]

I skim, but when making certain stocks, like chicken stock, I'll blanch the bones and meat first, rinse them, clean the soup or stock pot in which the meat and bones were blanched, add fresh water, and then start cooking. It substantially reduces the need to skim and results in a cleaner, clearer stock. It takes a little longer but, IMO, the results are worth it. YMMV

[huiray]

......

With pork bone stock/broth I should clarify that different bones and different intentions give rise to either clear stocks or very milky stocks. Simmering (cleaned) knuckle/shin pork bones with plenty of cartilage caps and collagen/tendon bits and plenty of marrow (preferably also w/ some meat still attached) for a very long time (I have done it for 8-9 hours and sometimes w/ an overnight rest and reheating again before separating the bones from the stock) gives a heavily gelatinous *and* milky stock - YUM! - which I use for things like a daikon + ground pork meatballs + vast quantities of ground white pepper soup. :-) Milky pork stock is also common for "real" bowls of ramen, of course.

...particularly Tonkatsu Ramen.

Here's a Food Lab report on making it:

http://www.seriouseats.com/2012/02/how-to-make-tonkotsu-ramen-broth-at-home-recipe.html

edited for spelling

Edited February 3, 2014 by huiray (log)

[dcarch]

When you boil stock or soup some of the proteins denature and if not skimmed will sit in bubbles on the surface in a cloudy grey mass and eventually breakdown and disperse creating a cloudy soup with speckles. Skimming gives a clearer, cleaner look and better visual appeal. If you object to skimming, try eating a few spoonfuls and see it that changes your mind.

Whatever in the soup is food, good food. (except fat, which I remove after refrigerated the soup).

I use a stick blender to give the soup a uniform look. No scum floating around

dcarch

Edited February 3, 2014 by dcarch (log)

[huiray]

Whatever in the soup is food, good food. (except fat, which I remove after refrigerated the soup).

In the Western tradition, perhaps. In the E/SE Asian tradition *some* fat is always a good thing. With Ramen broth (as I posted about above) lots of fat is a good thing in many cases. In many Chinese-type soups unctuous fat is appreciated. Ditto SE Asian soups. One need not go overboard, but a "soup" with zero fat in it is not the most appreciated soup in all cases in those traditions.

[pep.]

Not even in all western traditions. No Austrian Rindssuppe (beef broth) is complete without large Fettaugen ("fat eyes", i.e. little puddles of molten fat floating on top of the soup).

[Shalmanese]

Whatever in the soup is food, good food. (except fat, which I remove after refrigerated the soup).

In the Western tradition, perhaps. In the E/SE Asian tradition *some* fat is always a good thing. With Ramen broth (as I posted about above) lots of fat is a good thing in many cases. In many Chinese-type soups unctuous fat is appreciated. Ditto SE Asian soups. One need not go overboard, but a "soup" with zero fat in it is not the most appreciated soup in all cases in those traditions.

While many Asian stocks and soups have emulsified and unemulsified fats in them, there's definitely many highly prized clear soups and broths with no fat in them. Birds nest soup, for example, would be considered marred if it were clouded by fat.

[huiray]

...and by "Asian" you mean...what, exactly?

Turkish soups? Persian or Pakistani or Tukmenistani soups?

If you mean Chinese soups, why not say so? As for soups like Bird's Nest Soup sans any fat at all - I don't think of it that way . I would not think it defective if there were some fat present in it.

Edited February 3, 2014 by huiray (log)

[takadi]

I think he was referring to soups like suh lung tang and tonkotsu

[huiray]

Then it might be better to say "East Asian". Asia is a very large place, stretching from Turkey to Japan and swinging through India and the SE Asian nations & etc and Indonesia and Papua New Guinea etc etc. I believe Anthony Bourdain made some comments about the issue too. ;-)