Have you ever tried to thicken a dish, only to be disappointed with the results? Was it thin and runny, or perhaps it did stiffen up, only to thin out again?
As it turns out, choosing the appropriate thickener can be a dish-maker, or a dish-breaker.
Firming agents are a common addition to many recipes, from sauces and gravies to jams and jellies, to almond milk and baby formula.
So let’s have a look at the most frequently used methods for thickening soups, sauces, and gravies, their basic differences, and the most appropriate ways to use them.
For the home kitchen, the most common thickeners come from polysaccharides such as starches, vegetable gums, and pectin, and proteins like eggs and gelatin.
For sauces and gravies, starches are used. And these are usually derived from wheat, corn, potatoes, tapioca, or arrowroot.
The science of how starches work is pretty straightforward – Penn State’s online Kitchen Chemistry class gives a good explanation of the process.
When mixed with cold water, starch granules will absorb some of the liquid, but not all of it.
And if you try to give them too much all at once, they’ll gang together in clumps to repel the water – resulting in the infamous lumpy gravy. Adding water slowly helps to absorb more liquid, but the key to their thickening properties is heat.
Heat breaks down the weak spots in the granules, creating more room for the water to be absorbed. And once this happens, the agitated molecules form a network as they join together. This process is known as gelatinization, and it’s when your sauce begins to stiffen.
Cornstarch – is made from corn, and has twice the thickening power of flour.
It excels in firming up gravies and sauces, like the delectable sweet and sour sauce for this stir-fried shrimp dish.
Because of its transparent qualities, cornstarch is ideal for use with fruits as it allows their rich, vivid hues to shine through. Fruit fillings benefit from thickening with this type of starch as well as other desserts, like this homemade German vanilla pudding.
However, acidic ingredients such as lemon juice or vinegar can inhibit the thickening properties of cornstarch (and flour), preventing gelatinization.
Flour – Wheat flour is comprised of starch and proteins.
It’s a good thickening agent for sauces, stews, gumbos, gravies, and fruit fillings, as it imparts a smooth, velvety mouthfeel.
It also works very well when it’s mixed with a fat, making it ideal for creating a roux or beurre manié – more on those a little later.
When added to a sauce, it will become opaque. And, if cooked for too long, it may thin out again.
Potato starch – Gluten free, potato starch is all starch.
It can be used for stiffening gravies and soups, as well as baking. It’s also the starch of choice for Passover cooking.
When using potato starch, avoid boiling, which will reduce its gelatinous properties.
Arrowroot & Tapioca – Both starches are obtained from the rhizomes of South American plants.
Less commonly used than the others listed above, these are gluten free, won’t cause cloudiness, and work well with acidic ingredients.
A flour whitewash is created by whisking together flour and cold water. Once the mixture is well blended and smooth, it’s added to a simmering liquid and cooked for several minutes to remove the raw, pasty taste of the flour.
Not sure which type of whisk is best for the job? Check out Foodal’s review of the best whisks for your kitchen.
A cornstarch slurry is similar to a whitewash, except cornstarch is used instead of flour. The cornstarch needs to be dissolved in water so that no lumps remain, then added to the ingredients that are being cooked. Simmer for a couple of minutes until no starchy flavor remains.
A flat whisk, also known as a roux whisk, is an excellent selection for making thickened sauce bases and gravies. We recommend investing in this Cuisipro model available at Amazon.
You may not be familiar with the term, but you probably know the method – it’s the basic white sauce used for making a batch of homemade mac and cheese, like this one or this one. Or you might use it as the base for pan-drippings gravy.
A roux is created by mixing equal parts flour and fat, such as butter or pan drippings, and cooking over medium-low heat until it reaches a stiff, smooth texture.
When done, a roux has a rich, silky body and a light nutty flavor – which increases the longer it’s cooked. But, the longer it cooks, the less thickening power it will have as the gelatinization breaks down.
Roux can be made with vegetable oils, but they do have more of a tendency to separate. Clarified butter and rendered fat drippings are better mediums, as the flour will be suspended in the fat when it cools. And this cohesion will prevent lumps, when it’s mixed in with sauces or soups.
As soon as the flour is whisked into the hot liquid, it will stiffen into a rough paste. But at this point it will have a grainy texture and a raw, floury taste.
Simmering for 5 to 45 minutes over medium-low heat will soften the flour as it absorbs the liquid, cooking away the raw taste, and developing a toasty fragrance and flavor as it caramelizes.
Constant whisking is required when making a roux, to ensure that it doesn’t burn or separate.
- A white roux remains an off-white color, and is cooked only until the raw, starchy taste and fragrance is removed, for about 5 to 10 minutes. It will still have a slightly gritty texture, but will be much smoother than it was at the start.
- Used for cream soups, chowders, and white sauces.
- A blond roux is cooked a bit longer until lightly caramelized, approximately 15 to 20 minutes. It will now have a much silkier texture, and a light fragrance with a flavor reminiscent of toasted nuts.
- Used in pureed soups and meat sauces, or when a deeper flavor is required.
- A brown roux is cooked even longer until highly caramelized for 40 to 45 minutes, which results in a rich, nutty flavor and a caramel color.
- Used in brown sauces, gumbo, stews, sausage gravy, and dishes where a darker color is desired.
French for kneaded butter, this is a combination of equal parts flour and softened butter. Simply use your fingers to rub the two together until the consistency is that of a dense paste, and small rounds can be formed.
The rounds are then whisked into a sauce, chowder, or stew to finish a dish. When the butter melts, the flour is dispersed evenly without creating any lumps, adding shine to dishes and a lustrous, satiny mouthfeel.
A coiled whisk is perfect for stirring together sauces and preventing lumps from forming. Foodal recommends this model from OXO, available on Amazon.
Now that you know the basic differences between thickening agents, will it change the way you make your sauces and gravies?
Or, if you’re already skilled in this area, do you have any tips to share?
Let us know your thoughts and opinions in the comments below.
Photo credits: Shutterstock, Cuispro, and Kuhn Rikon.
About Lorna Kring
Recently retired as a costume specialist in the TV and film industry, Lorna now enjoys blogging on contemporary lifestyle themes. A bit daft about the garden, she’s particularly obsessed with organic tomatoes and herbs, and delights in breaking bread with family and friends.