Actually it isn’t, but I liked the sound of that for the headline. Reader Mark asks:
In my local Asian food market I can find a few different starches (Corn, Potato, Tapioca) pretty easy, and it would seem to some extent starch is starch, but that also seems a bit naïve on my part to think of them all as inter-changeable. Are there texture, flavor, or other reasons why I’d want to use a corn vs. any other starch in pudding?
Hey Mark! A very interesting question. There are quite a lot of starches that can be used as thickeners and all of them are a little different from one another. Cornstarch (corn flour) is a common one for pudding because it’s so readily available and can handle some boiling before the “gel” starts to dissolve. Cornstarch-thickened mixtures also hold their thickness after being frozen, though acid can inhibit it’s ability to thicken.
Wheat flour is of course another way to go, though it tends to impart a “cereal” taste and chalky mouthfeel if it isn’t cooked thoroughly first — i.e. in a roux. It has gluten of course, which some people prefer to avoid. It also has only half the thickening power of most other starches.
Potato starch is an effective thickener that can be sprinkled straight into a liquid without changing its flavor very much. The problem with potato starch is that the “gel” it creates dissolves almost instantly when it reaches the boiling point. Not being made from grain it’s a popular Passover thickener.
Tapioca (cassava) flour is another very common thickener that incorporates easily and thickens fully just before the boiling point, about 180 degrees Fahrenheit. It’ll thicken a liquid almost to the point of solidity which can be nice for pies, and it’s also acid-resistant, another handy feature. I personally don’t favor tapioca starch because when it thickens it tends to form somewhat stringy/stretchy constructions — instead of cornstarch “blobs” — which I find sorta yucky. Tapioca-thickened liquids also tend to thin out when they’re reheated.
Arrowroot is another lower-temperature thickener that works at about 165 degrees Fahrenheit, though it loses its oomph rather quickly as it reaches the boiling point. Like tapioca it’s a very good thickener to use with acidic liquids, but not with dairy products. Combine them and you get slime. Blechh.
So for a lot of reasons cornstarch is the go-to thickener for me, especially for pudding since it’s great with dairy and I don’t have to remember what temperature it thickens/thins at. I know that if it’s boiling it’s done. And that’s what I know about thickeners, Mark! Hope this helps!