Q. In an article on puddings, you used cornstarch as a thickening product. I have found arrowroot produces much silkier results, never clumps and is superior to cornstarch. Any thoughts?
When I'm writing recipes or choosing which ones to run, I try to stick with the most common ingredients. Arrowroot isn't hard to find, but cornstarch is more familiar and most cooks already have a box of good ol' Argo on hand.
But there are many starches that can be used in cooking. Besides cornstarch and arrowroot, there's potato starch, rice starch and tapioca. And of course, wheat flour is a starch.
All have advantages and disadvantages; it's just a matter of deciding what you want to do. Neither cornstarch nor arrowroot adds a starchy taste, and they thicken into a gel that is clear and silky. Both can “let go,” or lose their thickening power, if they are overstirred or overheated.
Arrowroot thickens acidic liquids better and it holds up better in the freezer. But it also can get a slimy texture when it's used with dairy products, which is probably why cornstarch is more common in custards and puddings.
Another difference is price: Cornstarch is usually much cheaper than arrowroot, although you sometimes use less arrowroot. But you can substitute arrowroot for cornstarch in most recipes if you prefer it or you like the texture better. I'm always in favor of expanding your repertoire and experimenting to figure out which ingredients you like best.