I’ve decided to devote a separate page to food thickening agents. Why? Well, as noted elsewhere in my website, attaining a certain expertise with sauce making is a big part of becoming a gourmet cook. And one cannot achieve this without a good understanding of the various food thickening agents used to finish the many varieties of sauces.
One of the most common methods for thickening sauces is through the gelatinization of starches. Gelatinization is the process by which starch granules are cooked. When they are added to a liquid and heated, the moisture is absorbs and the product thickens. Starches used to thicken sauces are cornstarch, flour, and arrowroot.
Here are the most common food thickening agents:
A roux is equal parts of flour and fat (butter, grease, etc.), cooked together to form a paste.
The three types of roux are:
- White roux – This type of roux has little color and should be removed from the heat as soon as it has a frothy, bubbly appearance. This roux is great for macaroni and cheese, creamed potatoes, etc. Any dish where you need a white color.
- Blond roux – This type of roux is cooked longer and starts to take on a little color. I use this kind a lot for chicken gravy. It is an ivory color.
- Brown roux – This roux is just cooked longer and is used in brown sauces, gumbo, etc. Be careful when cooking dark roux. It can go from dark to burned quickly and burned roux is not good.
Procedure for Preparing Roux
- Heat the butter or grease.
- Add all the flour and stir to form a paste.
- Stir often while you are cooking the paste to prevent burning. The roux should be fairly stiff.
Incorporating Roux Into a Liquid
- Use a whisk to stir (a little at a time) the cold stock into the cooked roux until thickened.
- After the roux is incorporated into the liquid, cook the mixture for 10-15 minutes to remove any flour taste.
Guidelines for Using Roux
- Don’t use an aluminum pot to make a roux. The roux will turn gray with all the scraping needed. Always use stainless steel pots.
- Make sure your stainless steel pots are heavy to prevent sauces from burning.
Cornstarch is pure starch derived from corn and is a natural food thickening agent. You shouldn’t re-heat products made with cornstarch as a thickener.
A lot of recipes calls for making a slurry which is a solution of a starch and a cool liquid. Cornstarch must be mixed with a cool liquid before it is mixed into a hot one. Once added, stir continuously until sauce thickens.
Arrowroot is similar to cornstarch (more expensive). It makes a clearer finished product.
Combining flour and softened butter to make a smooth paste makes a Beurre manie (burr mahn-yay). It is used for quick thickening at the end of the cooking process and it makes everything delicious!
And, don’t worry if you first few attempts aren’t all that great. There is a small learning curve. But I promise, your sauces will get better and better with practice. (My first sauce attempt was an unmitigated disaster – I don’t want to talk about it.)