Initial Boil to Get Rid of Impurities in Meat
Recently, I've been reading recipes that call for an initial boil of meat / bones to "get rid of the impurities." These recipes range from stock recipes to oxtail braises.
Just curious, how many people actually do this and does it affect the taste of the recipe? My mother (and I) always just skimmed the scum off the stocks as it cooked instead of boiling the bones first, giving the bones a quick rinse, and then adding fresh water to the stock pot.
I do this for stocks all the time (I learned it in Chinese cooking), and I find that it doesn't change the taste much, but does give you a much cleaner stock with less fuss than European
The 'impurities' in this case are basically the stuff that manifests itself as the scum and some of the floaty bits when you make stock from raw bones. I think it mainly comes from blood and tiny bits of stuff. The point about open air markets is a good one - I regularly buy chicken and pork in the traditional markets - no plastic wrap and foam trays there.
You don't actually lose much flavour, as the flavour in the stock comes from long slow cooking.
When I discovered this I was delighted. I've never bothered with clarifying the traditional French way with ground veal and egg whites as it seemed a waste of good food to me.
I have researched the internet looking for information about the foam that forms on the top of stocks or boiling foods. I found some opinions and ideas but, found no actual research or evidence saying the foam is uneatable or full of impurities.
It is not logical that you would be able to remove uneatable impurities from stock just by skimming or straining the foam from the top of the water/soup/stock.
My mother taught us, it was the coagulated blood of the animal, the base or bullion, hence the stuff that is the flavoring for soups and gravy.
However, later in years I saw a video demonstration on TAP WATER cooking- versus-FILTERED WATER cooking.
The video showed foam forming on top of a vatiety of boiling foods when using tap water and virtually no foam using filtered water. This was a companie's proof, showing the foam comes from impurities and chemicales in you tap water not your food.
I'm going to keep looking though! The truth is out there.
Here's an answer....
ArticleFoaming−Antifoaming in Boiling Suspensions†
AbstractFull Text HTMLHi-Res PDF[160 KB]Darsh Wasan,* Alex Nikolov, and Anal Shah
Department of Chemical and Environmental Engineering, Illinois Institute of Technology, 10 West 33rd Street, Chicago, Illinois 60616
Ind. Eng. Chem. Res., 2004, 43 (14), pp 3812–3816
Publication Date (Web): March 30, 2004
Copyright © 2004 American Chemical Society
AbstractParticle-stabilized aqueous foams are encountered in radioactive waste treatment and immobilization processes and in FOOD, CHEMICAL, and AGRICULTURAL products. The cause of foaminess in the presence of finely divided solids DURING BOILING and in the absence of any surface-active agents is NOT WELL UNDERSTOOD. Our research has identified at least two kinds of particles in such foaming systems, hydrophilic (i.e., water wet) colloidal particles dispersed in the aqueous phase and biphilic particles (partially wetted by water). The biphilic particles are attached to the air−water surface. In this study we used an advanced optical technique to characterize and monitor the number of nonattached (i.e., hydrophilic) and attached (i.e., biphilic) particles at the gas−liquid surface. The results clearly show that foaming increases with an increase in each of the two types of particles but to a different degree. The presence of biphilic particles causes a significantly higher degree of foaminess than the hydrophilic colloidal particles.
YES BUT, DOES REMOVING THE FOAM MATTER?
Well, here might be a better demo.
Boil a pot of tap water with nothing in it and boil a pot of filtered water with nothing in it. And see which one has foam. My guess? Neither.
The foam from the pot with tap water and bones is most likely the interaction from the minerals and sediments with the bones/meat. While filtered waters will vary, most have the sediments and minerals (e.g. fluoride) removed.
Just a wild guess.
Foam, no foam! I don't skim, never have.
I became curious after hearing someone speak about the foam in a very serious and emotional manner. They claimed it was all the poisons rising to the top, never to be consumed.
Going to the web, the information I found on the subject was based on opinion or best guess. So...I went science and it's up in the air there too.
I always thought of skimming being a personal preference. It looks like it still is.
No one said that the impurities are not edible but they're not particularly palatable, have little culinary value and are removed soley because they cloud the stock, which is not acceptable in the finished product.
It is very logical that impurities can be skimmed off the top of the stock while the stock is simmering. I don't understand why you would think otherwise. After the stock is finished, it's strained, removing the bones, vegetable matter and further impurities and chilled, and the fat is removed. You may misunderstand the meaning of the word impurities. In the case of stock, it's fat and soluable cell proteins that coagulate and cloud the stock. That's all it means. These impurities are the soluable proteins that have escaped the solids in the stock, form aggregates and rise to the top of the stock while cooking, then are removed by skimming.
Using coagluated blood as flavoring or thickening a sauce is one method of cooking, but it's not a component of a well made stock.
I hope to heaven that foaming on stock is not due to my tap water. I would think that using filtered water might be a case for a part of the world where the tap water is contaminated, for whatever reason, and the local population is inclined to use filtered water for cooking. That is not the case where I live. I propose that if you made stock with filtered water, you would still have the foam rise to the surface of the stock. It's inherent in the meat and bones, not the water.
For the short period of time your bones are in the initial simmer, there is no loss of flavor, but a significant loss of impurities and coagulate proteins on the meat and bone surfaces that will cloud your stock. All your doing is bringing the water to a simmer. As soon as it reaches that stage, drain and rinse.
For the second step, simmering very slowly (bubbles just breaking the surface) and skimming frequently will further your chances for a clearer stock.
I use the two step method for making a white stock. For a brown stock, where the bones and vegetables are browned before simmering, I don't.
I use this method all the time. I cook a lot of korean soups but actually learned this from a vietnamese cookbook. If you want a clean, clear soup/stock, there is no better method.
as for boiling away the flavor, I'm sure some is lost but its minimal and you certainly get a reduction of the bitter/irony flavor of blood and scum. I still skim using this method.
Note that flavor is not the only component of a good soup. Mouth feel is also critical. The colligen doesn't get release with the first boil so your soup/stock will have some awesome mouth feel.
Remember, after the first boil also clean the pot as a lot of scum sticks to the pot.
I'll have to research this. My instinct is that it sounds bogus.
Seems like after thoroughly rinsing the meet prior to cooking, you would never want to throw out water from an initial boil, as you would be throwing away flavor/nutrients. Everything I read about slow cooked braises or stews talks about retaining flavor and folding it back into the dish.
What impurities are we talking about here. I realize there could be many, but are we talking germs, residue from non-organic feed, what?
Lived in Korea 3 years and studies cooking techniques there. Have never heard of this technique in korean cooking.
The initial soak is to loosen congealed blood and any caked dust/dirt/grime.
The initial boil and subsequent rinse is to remove the loosened matter, bone dust/fragments that embed in meat from cutting, and insect leavings.
This method is traditional and is probably due to the fact that until fairly recently meats were sold from open air markets with no refrigeration, no glass cases, and no packaging.
This may have changed somewhat in recent years as Korea has modernized a great deal in the past 3 decades and a number of restaurants have incorporated some western methods.
Another factor is that a great many Koreans found the smell of some boiling meats (mostly pork) to be unpleasant, thus the addition of ginger to the boiling pot.
I do this all the time with whole chickens (for chicken soup), beef (for beef stews and the like), pork ribs and bone (for pork bone soup), as well as oxtail.
I've never found that this affected the taste in any way but in a positive fashion -- makes the soups or stews taste a bit "cleaner" if that's a right word to use.
Note, this is for soups, not for making stocks (which normally I use only things like chicken feet, neck, wings, bones, etc.)