Cornstarch is made from corn, is a fine, white powdery starch ingredient that is used to thicken pie fillings, sauces, gravies, and puddings, as well but it doesn't thicken well when mixed with acidic liquids.
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. For more cornstarch problems with solutions, go to THICKENERS – CORNSTARCH.
This how to baking technique is used with the Chocolate Pudding Filling Recipe Tutorial
HOW TO TIPS:
1. Combine the cocoa and boiling water in a small saucepan over low heat. Stir in the sugar and chopped chocolate.
3. Dissolve the cornstarch in cold water in a small bowl and stir to make a smooth paste.
SARAH SAYS: Gradually stir cold liquids into corn starch until completely smooth.
4. Add the dissolved cornstarch paste and salt to the pan (of hot cocoa powder, water, and sugar, with melted chocolate) and bring to a boil, stirring constantly. Boil for one minute.
SARAH SAYS: Cook over medium-low to medium heat. Cooking over high heat can cause lumping. If mixture contains egg, high heat may curdle it.
Stir gently during entire cooking period. Stirring too vigorously may cause mixture to break down and thin out.
After boiling 1 minute, the starch granules will have swelled to their full capacity, causing the mixture to thicken. Significantly overcooking thickened mixtures such as puddings, pies and cake fillings may cause mixture to thin out as it cools.
5. Remove from heat and strain the mixture if lumps appear.
6. Then whisk in butter and vanilla.
SARAH SAYS: When adding ingredients after cooking, remove the mixture from the heat and stir them in quickly and gently.
7. Transfer the mixture to a bowl, cover with plastic wrap, pressing it to the surface of the filling. Refrigerate until cool before using in the recipe.
SARAH SAYS: Freezing corn-starch thickened mixtures will rupture the starch cells and cause the mixture to thin out.
