Sunday, March 16, 2014

Sauces, Gravy and Separating the Fat

Making gravy and other thickened sauces is not difficult but a surprising number of cooks fear this activity. I suppose we've all had lumpy gravy and wondered what went wrong, or the sauce that seemed properly thickened only to turn back to a loose liquid minutes later. So today I wanted to share with you my thoughts on this important subject, and perhaps the most important tip of all in making gravy, how to separate the flavorful sauce from all that fat.

Thickening Techniques
Today's post is not just for gravy, because you may also need to thicken a soup, a stew, sauce or even a pie filling. To thicken these, I use one of three basic techniques. The roux, the beurre manié, and the slurry. Don't let the names scare you.

Roux:  A roux is simply equal parts of flour and butter that are cooked in a pan until they are completely combined, thick and smooth.  The mixture is then cooked briefly, just long enough to remove any raw flour taste. The word "roux" is French for "reddish-brown", and the longer you cook the mixture, the darker the color and the nuttier and more complex the flavor. Most of us simply cook it quickly until it is light tan, and then the hot liquid is whisked into it, in batches, returning it to a simmer prior to each addition, until the desired consistency is reached.  It is done in batches and returned to a simmer each time because a roux's full thickening power is not realized until the liquid is brought back to a simmer. But of course, this only works if you know you need more thickening up front when you first prepare the dish. But what if you decide at the end of the dish, it isn't thick enough. Then it's on to the below two options.

Beurre Manié: This is a mixture of equal parts flour and softened butter, which, when whisked into hot sauces, acts as a thickener. This is also easy to prepare and again I don't measure. Just aim for equal amounts of butter and flour by weight, and using a fork work the flour into the butter until you have a pasty dough. The beurre manié is traditionally dropped into the hot (but not boiling) liquid a piece at a time and whisked in for a minute or so to see if the sauce is thick enough. If not, more can be added. Continue cooking the sauce for another 10-15 minutes over low heat to ensure the flour leaves no taste in your sauce.

Slurry or Whitewash:  This is the home cooks 'go to' method for making gravy and thickening sauces when they are nearly completed. A slurry is simply a 1:4 ratio of starch and COLD water, broth or juice that is mixed together in a small bowl or lidded glass until they are combined. The ratio is forgiving and I never measure it. If you add the starch directly to the hot liquid it clumps. But it does not do so when first mixed with a cold liquid. Once you combine the slurry, slowly pour it into the simmering hot liquid a bit at a time while whisking until you reach the desired thickness. (Note, do not pour it into a rolling boil, just heat until simmering and near but just under the boiling point for best results.)

Flour is the most common starch used in American slurries, although corn starch, potato starch, arrow root or tapioca can also be used for thickening. Use my table below to determine your preferred thickening agent for the slurry. I keep all of them on hand. Also note, you cannot thicken a sauce twice with the same thickener. For example if you made a roux with flour to begin your dish and toward serving time feel it needs to be thicker, use corn/potato starch as it will not thicken again with flour.

Know Your Thickeners 
Understanding the different thickening agents is not only important for sauces and gravies but also for thickening pies, custards and other dishes. Each have their own benefits and drawbacks and understanding them will help you to determine which container to pull off the shelf when you have the need for thickening.

Flour: Opaque mat finish. Tolerates prolonged cooking. Favorite use: meat gravy.

Corn Starch: Clearer and more efficient than flour with a glossy finish. Don't use in acid dishes or sauces you intend to freeze. Does not tolerate prolonged cooking. Favorite use: Asian sauces. 

Potato Starch: Translucent glossy sauce. Gluten-free starch, permitted ingredient for Passover. Do not boil. Thickens at lower temperatures. Silky mouth feel. Favorite use: soups, gravy, pies.

Arrowroot: Tasteless and translucent. Shiny sauce. Freezes well. Do not use in dishes with cream. Thickens at a lower temperature. Tolerates prolonged cooking. Silky mouth feel. More expensive. Favorite uses: Fruit pie fillings.

Tapioca Starch: Don't by the little balls. This is a powder. Makes a clear, shiny sauce. Freezes well. Tolerates prolonged cooking. Glossy sheen with silky mouth feel. Favorite uses: pies and fruit sauces.

Food Grade Gums:  You might wonder why restaurant and pre-made foods have no trouble holding their thickening. That's because they use commercial grade products like gums.  Food grade gums are are the thickening agent of choice in commercial food preparation. They’re gaining popularity in the home kitchen because they are extremely neutral in flavor and are added in such low concentrations they have no effect on color or flavor. Xanthan gum, which can be found in health foods stores because it is gluten free, is even sold on Amazon.

Separating Fat from Flavor
Liquid fat must be separated from the drippings of a roast before making gravy or from a pot stock before turning it into soup. In looking back at my prior posting on making Stock, Broth and Soup I told you to remove the fat from the broth, but I didn't explain how. So today I will correct that and give you my two favorite methods; the specially designed fat separator (or gravy strainer) and the fat mop. Both work well.

Oxo Good Grips Separator
As you probably know fat separators work because 1) fat and water do not mix and 2) because fat rises above the liquid. As such both of my tools remove the fat from the flavorful broth. You may wonder why you would want to do this if you are not worried about your health, as fat transmits flavor in your mouth. Unfortunately it also makes the mouth and tongue feel greasy, which is not what you want in your soup, stew or sauce.

The classic 'gravy strainer' (shown right) works well but only if you select the correct model. I strongly prefer the large, 4-cup model with a strainer on the top, like the Oxo Good Grips Fat Separator.  The large opening is easier to fill and the plastic cup less likely to break as they can become slippery, and solids are more easily trapped.

The Fat Mop, which has a mop head made of plastic fibers that attract fat, is great for removing fats from soups, stews and gravies when it is not possible to use the traditional fat separator. You simply run it across the surface and it collects the fat. Use it any time you have a sauce or other dish that is already prepared and needs the fat removed from the top, but not for a large quantity of liquid for which the traditional separator works best.

Fat Mop

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