How To Make White Stock  

MAKING WHITE STOCK
Let's summarize the procedure for making white stock before delving into the why questions. The first step in stock making is to rinse the bones in cold water. Once rinsed, place the bones in a large stockpot (preferably lined with stainless steel, as aluminum can sometimes discolor certain stocks) and fill with cold water, just enough to cover the bones by 1-2 inches.
(For our photo shoot we used chicken with meat still on the bones. Typically you would use straight chicken bones (without meat) to keep the cost down.)

Bring the water to a boil over moderate heat. Once the water has boiled, reduce heat immediately so that the stock is barely simmering. Using a ladle, skim the top of the water to remove any fat and/or impurities (scum).

At this point, add the flavoring components (vegetables, herbs, and spices) to the stock. Chefs refer to the vegetables in stock as mirepoix (French, pronounced mir-pwa). For white stocks, mirepoix generally consists of 2 parts (by volume) onion and 1 part celery. Many chefs vary the composition of mirepoix with such additions as well-washed chopped leeks or carrots (which in too great a quantity will both sweeten and add a dark orangy hue the finished stock). The mirepoix is generally cut in large 1/2 inch to 1 inch pieces. The longer a stock cooks, the larger the mirepoix is cut.

Herbs and spices (bay leaf, thyme and black peppercorns) are added to stock in one of 2 ways. If using fresh thyme, prepare a bundle, or "bouquet garni" in French. To do this, cut a 2 inch piece of celery, place a couple of branches of fresh thyme and parsley stems in the cavity of the celery. Top with a bay leaf, and tie it securely with kitchen string. Dried ingredients like thyme, peppercorn and sometimes bay leaf are put in a stock in a "sachet." To make a sachet, place dried ingredients on a square of cheesecloth. Wrap up the cheesecloth to make a bag (or sachet), and tie with a string.

Continue cooking the stock at a very slow simmer for the prescribed length of time. A good rule of thumb is this: fish and vegetable stocks--30 minutes, poultry stock--2-3 hours, and veal stock** 8-12 hours. Whenever impurities or fat rise to the surface, skim them off carefully using a ladle. When the stock has cooked long enough to extract all the gelatin from the bones and flavor from the vegetables, herbs and bones, ladle (or pour very carefully) the stock through a chinois (fine mesh conical strainer). Remove the stock from the stockpot as gently as possible. If it is poured carelessly, one could stir up small solid particles that typically settle to the bottom of the stockpot during cooking. If these are stirred up, the stock could become cloudy. When straining through a chinois, do not press on any solid ingredients that fall into the chinois. Not only can this cloud the stock, but a sharp bone could pierce the mesh of the chinois, thus rendering this expensive utensil useless. If the stock strains too slowly, you can tap on the edge of the chinois to speed the process.

Once strained, professionals always chill stock in an ice water bath. This is the fastest way to cool a stock. Once cold, store for up to several days, covered, in the refrigerator. Stock also freezes very well.

THE WHYS
Knowing how to make stock and really understanding why we do what we do, are two different things. So let's retrace our steps and discuss some of them in more detail.

We always start making a stock using cold, never hot, water. Cold water is necessary to make a stock that is crystal clear and not cloudy or murky. When a stock starts with cold water and is heated gently to the boiling point, the proteins in the bones and meat will have time to slowly coagulate, clump together, and rise to the surface in the form of scum. This scum can then be easily skimmed off.

Once the stock reaches the boiling point, it is crucial that the heat is reduced immediately so that the stock simmers slowly for the remainder of the time. If the stock boils hard for any length of time, the coagulated protein and fat that rose to the surface of the stock will be churned back into the stock. This creates a greasy and cloudy stock which is considered a grave fault in stock making. Sometimes a lengthy period of simmering will correct the cloudiness, but if the stock has sufficiently churned and boiled it is hopeless.

Why add the mirepoix after the first boil and not along with the bones and cold water? True, this would extract more flavor from the vegetables, but they will have plenty of time to cook even if added after the first initial boil. The answer is strictly a practical one. When a stock first comes to a boil, it will produce the greatest amount of scum. With no mirepoix added to the pot, it is simple to skim off the scum and fat without removing any of the aromatic ingredients.

Why bother making a sachet or a bouquet garni? The answer is basically the same as for the mirepoix. While the stock is simmering, it is necessary to skim it from time to time. If we don't contain the herbs, we will likely skim them off the top of stock along with the fat and scum. This, in effect, removes flavor from the stock.

Lastly, why chill a stock in an ice bath? Most home chefs do not do this, but it is an excellent practice to get in the habit of doing. Basically, it is a question of bacteria. Stock is a great medium for bacterial growth. Bacteria love to grow between 40-145 degrees. Chilling stock in ice water lowers the temperature of the stock rapidly. The stock does not then spend much time between 40-145 degrees and this greatly reduces the possibility of bacterial growth.

**When making a white veal stock, it may be necessary to first blanch the bones. To do this, cover the rinsed bones with cold water. Bring to a boil. Drain water from bones and rinse the bones again. Cover the bones with new fresh cold water in the stockpot and bring to a boil over moderate heat. Continue as with any other white stock by adding the mirepoix,etc. Blanching veal bones is a trick to keep the stock from turning a dark, murky color.

BASIC WHITE CHICKEN STOCK
Yield: 1 1/4 Gallons.
INGREDIENTS
10 lbs chicken bones, coarsely chopped (chicken legs--drumsticks--are inexpensive and very flavorful)
1 lb mirepoix (2/3 onion and 1/3 celery--and possibly a bit of leek and 5 garlic cloves)
1 bouquet garni using several branches of fresh thyme, parsley, and 1 bay leaf
1 T. whole black peppercorns wrapped in a sachet
cold water to cover

METHOD
Rinse bones. Cover with cold water. Bring to a boil over moderate heat. Skim. Add remaining ingredients. Simmer for 2 1/2-3 hours, skimming frequently. Strain through a chinois and chill in an ice bath.