Basic Stovetop Custard RecipeFood thickeners frequently are based on either Polysaccharides (starches, vegetable gums, and pectin), or proteins. A flavorless powdered starch used for this purpose is a fecula (from the Latin faecula, diminutive of faex meaning "dregs"). This category includes starches as arrowroot, cornstarch, katakuri starch, potato starch, sago, tapioca and their starch derivatives. Vegetable gums are used as food thickeners include alginin, guar gum, locust bean gum, and xanthan gum. Proteins used as food thickeners include collagen, egg whites, furcellaran, and gelatin. Sugars include agar and carrageenan. Other thickening agents act on the proteins already present in a food. One example is sodium pyrophosphate, which acts on casein in milk during the preparation of instant pudding. (Wikipedia)

Substituting one for another is tricky; Different thickeners may be more or less suitable in a given application, due to differences in taste, clarity, and their responses to chemical and physical conditions. For example, for acidic foods, arrowroot is a better choice than cornstarch, which loses thickening potency in acidic mixtures. At (acidic) pH levels below 4.5, guar gum has sharply reduced aqueous solubility, thus also reducing its thickening capability. If the food is to be frozen, tapioca or arrowroot are preferable over cornstarch, which becomes spongy when frozen.

STARCH THICKENERS: These silky powders are used to thicken sauces, gravies, pie fillings, and puddings. They're popular because they thicken without adding fat or much flavor, but some tolerate heat better than others. Starch is the major storage product of the world's most important food crops and is found in large quantities in the seeds of cereals (such as wheat, corn and rice), in legumes (such as pea) and in tuber and root crops such as potato and yam.

  • Cornstarch, flour, and tapioca are the most popular starch thickeners. They have different strengths and weaknesses, so it's a good idea to stock all three in your pantry. I seldom use arrowroot. Although flour is the traditional thickening agent in French cooking, cornstarch is a more powerful thickener because it is a purer form of starch. It will also create a clearer, shinier sauce.
  • Starch thickeners give food a transparent, glistening sheen, which looks nice in a pie filling, but a bit artificial in a gravy or sauce. If you want high gloss, choose tapioca or arrowroot.  If you want low gloss, choose cornstarch. 
  • Cornstarch is the best choice for thickening dairy-based sauces. Arrowroot becomes slimy when mixed with milk products.
  • Choose arrowroot if you're thickening an acidic liquid. Cornstarch loses potency when mixed with acids.
  • Sauces made with cornstarch turn spongy when they're frozen. If you plan to freeze a dish, use tapioca starch or arrowroot as a thickener.   
  • Starch thickeners don't add much flavor to a dish, although they can impart a starchy flavor  they're undercooked.  If you worried that your thickener will mask delicate flavors in your dish, choose arrowroot.  It's the most neutral tasting of the starch thickeners.  
  • Tapioca starch thickens quickly, and at a relatively low temperature.  It's a good choice if you want to correct a sauce just before serving it.

Starch thickeners often lump if not added to the liquids properly. To avoid lumps, mix the starch with an equal amount of cold liquid until it forms a paste, then whisk it into the liquid you're trying to thicken. Once the thickener is added, cook it briefly to remove the starchy flavor. Don't overcook--liquids thickened with some starches, such as flour and arrowroot, will thin again if cooked too long or at too high a temperature. 

If you get lumps in your sauce from a thickener, blend the sauce in a blender or food processor until it's smooth or strain it.

ARROWROOT:  A starch obtained from the rhizome of a West Indian plant. Sold as a dried and milled white powder. Does not mask or alter natural flavors. Produces sauces and pastes of remarkable clarity. Use as a thickening agent in place of flour or cornstarch for fruit sauces, puddings, salad dressings, dessert sauces, vegetable sauces, and meat glazes. Do not use to make gravy. Arrowroot reaches maximum thickening at lower temperatures than other thickeners, thus it is ideal for use with heat sensitive foods. Because it begins to thicken long before the boiling point of fruit fillings in pies, arrowroot is not a desirable choice.

CLEARJEL® = ClearJel® starch = Clear-jel: This modified cornstarch is the secret ingredient that many commercial bakers use in their fruit pie fillings. Unlike ordinary cornstarch, ClearJel® works well with acidic ingredients, tolerates high temperatures, and doesn't cause pie fillings to "weep" during storage. ClearJel® is an especially good choice if you're canning homemade pie fillings, since it doesn't begin thickening until the liquid begins to cool. This allows the heat the be more evenly distributed within the jar during processing.

ClearJel comes in a powdered form, just like cornstarch, and you basically mix liquid and sugar with it, heat over medium heat and stir with a heavy spoon until thick, add a little lemon juice and boil 1 minute. Then stir in fruit and cool and use, or you can cool it and then stir in fruit. It freezes well, and it's perfect for processing canned pie fillings.  ClearJel® is available from the supermarket or online

Chocolate Pudding Filling RecipeCORNSTARCH: made from corn, is a fine, white powdery starch ingredient (carbohydrate) that is used to thicken pie fillings, sauces, gravies, and puddings, as well. Cornstarch is called cornflour or maize cornflour in Britain, Australia, and New Zealand. Don't confuse cornstarch with the finely ground cornmeal that Americans call corn flour. Go to THICKENERS - HOW TO USE CORNSTARCH

Cornstarch has twice the thickening power of flour, but like flour, it imparts a slightly starchy taste, especially true in juicy summer fruit pies; that's why I recommend cooking part of the fruit and cornstarch before baking a pie. It yields the smoothest texture and does not thin when reheating a slice of pie. But, it must be used properly.

Cornstarch doesn't stand up to freezing or prolonged cooking, and it doesn't thicken well when mixed with acidic liquids. It can be kept indefinitely if stored in a cool, dry place.

Corn starch mixtures that don't thicken at all, or thicken during cooking, then thin out during cooling are disappointing. One or more of the following may have caused the problem: (from

* Too Little Liquid: If there is not enough liquid (water, milk, juice) in the mixture, the corn starch granules will not fully swell and remain thickened when the mixture cools. Adding a little more liquid (not more corn starch) is likely to solve the problem.

* Too Much Sugar: A higher proportion of sugar than liquid (water, milk, juice) in a mixture can interfere with the swelling of the corn starch granules and prevent thickening during cooking and/or cause thinning during cooling. Adding more liquid (not more corn starch) will often solve the problem.

* Too Much Fat: An excessively high proportion of fat or egg yolks in a mixture can interfere with the swelling of the corn starch granules and prevent thickening during cooking and/or cause thinning during cooling. Adding more liquid (not more corn starch) will usually solve the problem.

* Too Much Acid: Acid ingredients such as lemon juice, lime juice or vinegar will reduce the thickening ability of the starch or prevent the mixture from thickening. Increase the starch level slightly or stir acid ingredients in after cooking.

* Too Much Stirring: Excessive or rough stirring with a wire whisk or even a spoon may break the starch cells and cause the mixture to thin out.

* Excessive Cooking: Simmering or boiling a corn starch thickened mixture for an extended period of time may cause the starch cells to rupture and the mixture to thin.

* Undercooking: Weeping or the release of water is usually a sign of slight undercooking. In the early stage of cooking, the water is held rather "loosely" by the corn starch granules, and when the mixture cools, the water simply runs out. It's simple to stop weeping. Just be sure to bring the corn starch mixture to a full boil over medium heat and, stirring constantly, boil for 1 minute.

* Tasting: The digestive enzymes in a person's mouth will cause a properly thickened mixture to thin dramatically in just a few minutes. Be sure to use a clean spoon when tasting a corn starch thickened mixture to correct the seasoning.

* Freezing: Freezing corn-starch thickened mixtures will rupture the starch cells and cause the mixture to thin out.

FLOUR (See also, Roux): Wheat flour is a good thickener for pie fillings, gravies, gumbos, and stews, since it gives them a smooth, velvety texture. It's best to mix it with fat first, either by making a roux or beurre manié, or by flouring fruit for a pie first before filling a pie shell. If making stovetop sauces, cornstarch and flour mixtures start to thicken at 144 to 162 degrees F. These starches complete the final thickening process at 205 degrees F. Under-cooking does not allow starches to reach their maximum thickening capability. Sauces thickened with flour become opaque, and they may become  thin again if they're cooked too long or if they're frozen and then thawed. NOTE: High amounts of acid in food may prevent starches from setting.

FLOUR - INSTANT BLENDING: = instantized flour = quick-mixing flour:  You can sprinkle this finely milled all-purpose flour into liquids without getting many lumps, so it's perfect for making gravies and batters. It's also good for breading fish. Wondra flour and Shake & Blend are popular brands.  

POTATO STARCH (POTATO FLOUR): Gluten-free potato starch is 100 percent starch, whereas potato flour is about 85 percent starch, the rest being largely fiber, protein, fat, and sugar. Potato starch is pure white, while potato flour is yellowish, having traces of color and flavor from the potato. Potato starch is used to thicken soups and gravies, and does a better job at thickening fruit pies than potato flour, which tends to clump and turn opaque, rather than clear. Its main advantage over other starch thickeners is that it's a permitted ingredient for Passover, unlike cornstarch and other grain-based foods. Liquids thickened with potato starch should never be boiled because it will loose its power to thicken. Supermarkets often stock it among the Kosher products.

ROUX: This is a thickener that's made from equal weights of flour and a fat, like butter or meat drippings, whisked together in a saucepan over heat in order to ameliorate the flavor of the flour and to remove lumps. It is then added to sauces and gravies to thicken while cooking together. Or, additional ingredient are added such as cream, cheese, tomatoes, herbs, egg yolks, white wine, lemon, onions, peppers, etc. or combinations thereof can be added creating different sauces.

The most basic white sauce is based on a roux, which are equal volumes of butter and flour. The thickness of the sauce is easily varied by changing the proportion of roux to liquid. For a thinner sauce, use 1 tablespoon each of butter and flour to 1 cup of liquid; for a medium sauce, 2 tablespoons each; for a thick sauce, 3 tablespoons each. These two basic sauces, a béchamel and a velouté, are the basis for classic French white sauces.

To make Roux, heat the fat in a pan, then gradually whisk in the flour. Cook the mixture, stirring constantly, for at least several minutes, then gradually whisk in the hot liquid you're trying to thicken. It must be cooked for at least 30 minutes in order to rid itself of the flour's starchy flavor, to thicken the liquid and to get rid of the flour's white color.  

Classic Double Crust Peach Pie RecipeTAPIOCA: Tapioca is made from starch extracted form the root of the cassava plant, also called manioc or yuca. It comes in various forms, with pearl (also known as pellet or bead), (non-wheat) flour, and the tiny-grained instant or quick (or Minute, a trademark) being the most common. Go to THICKENERS - HOW TO USE TAPIOCA

Pearl tapioca, which comes in various sizes, and is used almost exclusively to make tapioca pudding, lending body and texture. They need to be hydrated where the white pearls become translucent, slightly swollen, and jelly-like. If you find only pearl tapioca, just place it in a spice grinder, blender, or food processor and grind away. Now you have small tapioca beads, but it has to be hydrated.

Tapioca (non-wheat) flour has considerably less thickening power than pearl tapioca. Commercial establishments use it mostly for soups, fruit fillings, and glazes. In Asian cuisine it is called tapioca starch and is almost as popular as cornstarch for use as a thickener in both sweet and savory dishes. It creates a perfectly smooth filling and imparts a high gloss for a tasty-looking result.

Instant or quick-cooking tapioca are little white "beads". It is made by mixing tapioca flour and water to form a dough, which is slowly cooked and stirred. The dough is then dried, pulverized, and cooled, forming more uniformly sized and shaped granules, which do not require hydrating before using, but they they only need to be moistened and heated in order for the tiny pellets to swell and become opaque in color. It is most desirable in puddings and in juicy summer fruit pie fillings in a two-crust pie. And, to use as smaller partcles, just place it in a spice grinder, blender, or food processor and grind away.
SARAH SAYS: Start with adding 3-4 tablespoons of instant tapioca for 6 cups of juicy fruit, or a generous, rounded 1 1/2 teaspoons per cup of fruit. If your fruit is a little less juicy, use a scant 1 1/2 teaspoons per cup. You can adjust the thickening to your tastes.

Each thickener has a different attribute and is used based upon the recipe being made.

AGAR AGAR: Agar agar is a gelling agent made from a combination of algae from the species gelidium. Other names include dai choy goh, Japanese isinglass, or kanten, in reference to the dish in which it is commonly used. The name, agar agar, is Malaysian in origin, and the harvest of the long red and purple fronds goes back hundreds of years. The fronds are freeze dried and dehydrated naturally, producing colorless sheets which are shaped into bars. Agar is available in the traditional bars, flakes, and powder, all of which can be used interchangeably for gelling purposes. Long strands of agar are one of the ingredients in the seaweed salad served at sushi restaurants.

The mechanics of cooking with agar differ slightly from those of gelatin. Generally, powdered agar can be substituted in equal measure for powdered plain gelatin. In substituting agar for gelatin, remember that agar may not set when mixed with vinegar or foods high in oxalic acid, like spinach, chocolate, or rhubarb. Agar gelled liquids will stay solid at room temperature, while gelatin will eventually melt. To use agar bars, rinse them in cold water, wring them out and tear in small pieces, then add to the cooking liquid. One agar bar is equal to four tablespoons of flakes or two teaspoons of powder, and one bar or its equivalent will gel two cups of liquid. Unlike gelatin, all forms of agar need to simmer for a while to dissolve, and letting them soak in the liquid for an hour or two gives you a head start. from

CHOCOLATE: Did you know that ounce-for-ounce unsweetened chocolate has more thickening power than bittersweet? Cocoa solids are rich in starches, with unsweetened having more. When it was used in a Ganache filling recipe, it was significantly stiffer and also had a viscous, gummy quality. When made only with bittersweet chocolate, it had a pleasantly smooth and creamy texture.

Comparable amounts of bittersweet or semisweet chocolate and unsweetened chocolate plus sugar will not produce identical recipes. While a direct swap might work well enough in fudgy brownies, it could wreak havoc on a delicate custard or filling. 

COCOA POWDER: Cocoa powder is a starch thickener and is used in savory dishes. 

DAIRY: Cream, once reduced, gives sauces a rich texture and flavor as it thickens them, but it's high in fat. To make a low-fat cream sauce, use evaporated milk mixed with a starch thickener. Yogurt is a popular soup thickener in Eastern Europe and the Middle East.  

EGGS: Egg yolks make wonderful thickeners--imparting both a rich flavor and velvety smooth texture. You can't just whisk them into a simmering sauce--they'd curdle on contact. Instead, you need to "temper" them by adding some of the hot liquid to the egg yolks, whisking the mixture together, and then adding it to the sauce. Finally, never cook sauces with egg yolks in aluminum pans or they'll turn gray.  

Mango Mousse RecipeGELATIN: Unflavored gelatin is an odorless, tasteless and colorless thickening agent, which must be rehydrated in cold water, heated and melted and then dispersed, before the liquid will become jelled when cooled, especially when refrigerated to set. It is a much more powerful thickener than eggs, so it gives the recipes (custard) enough body to hold its shape when sliced. 

Gelatin is used in such recipes as Café Brûlot Chiffon Pie, Lemon Mousse, Chocolate (Stabilized) Whipped Cream or in cheesecakes, as well as fillings custards or other desserts to thicken and stabilize it.
SARAH SAYS: Let a gelatin-set custard cool and thicken slightly before folding in any whipped cream or beaten egg whites to assure maximum volume.

Gelatin commonly found in grocery stores is pure protein derived from animals, but there are other forms of gelatin to fit all types of diet restrictions, including vegetarian and kosher.

Gelatin comes in a granulated from the grocery store or sheet form, called leaves, available from specialty stores or online.
SARAH SAYS: I prefer to use the granulated kind because it is readily available in the supermarket. I use Knox gelatin, which is widely available and is considered the standard in the US. It comes packaged in boxes of 1/4-ounce envelopes and is also available in bulk. Leaf gelatin comes in packages of paper-thin sheets.

Gelatin's setting power has to do with the density of the liquid being set. Gelatin is always used in a ratio to liquids in the recipe: usually 1/4 ounce of powdered gelatin is needed to set 16 ounces of liquid. To obtain a "semi-solid" consistency, increase the liquid to 32 ounces.

It is extremely important to achieve the correct ratio of gelatin to water, and the recipe will always tell you how much to use. For example, a finished cream firmed with gelatin, should have a tender and smooth texture, yet have structure. If it is incorrect, it will be either runny or too firm and rubbery.

Unprepared gelatin has an indefinite shelf-life as long as it is wrapped airtight and stored in a cool, dry place.

Note that certain fresh fruits contain enzymes that break down the gelatin, such as figs, pineapple, kiwi, papaya, mango, and guava. They should be cooked before being used in a gelatin-set custard to denature their enzymes. (Canned fruit does not need to be precooked because it is pasteurized at a high enough temperature to denature their enzymes.)

PECTIN: Pectin is a high-fiber carbohydrate with thickening properties that occurs naturally in the cell walls of various fruits. Pectin is what makes jam happen. It's a natural thickening substance found in many fruits like strawberries and apples etc. Usually fruits that are slightly underripe are highest in pectin. This is why many older recipes (ones that you don't add powdered or liquid commercial pectin) call for ripe fruit and underripe fruit.

For the pectin to set you need both acid and sugar. This is why you can NOT deviate from the recipe in jam making. Old fashioned recipes will ask you to cook the mixture to the "jam stage" which is when you spoon some mixture and let it slide off the spoon. If it is not done it will just run off, if it is cooked correctly it will slide off, but leave a "sheet" attached to the spoon.

Newer recipes that call for added commercial pectin will have very specific directions. These directions are for the purpose of setting up the pectin and must be followed to the letter. In most recipes powdered pectin is added to preserves and jams, and liquid pectin is used in jellies.
SARAH SAYS: 2 tablespoons liquid pectin = 4 teaspoons powdered pectin.

VEGETABLE GUMS: Vegetable gums used as food thickeners include algininGuar Gum, and Xanthan GumLocust bean gum, also known as St. John's bread, carob bean gum; A vegetable gum derived from the seeds of the carob tree.

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