A Starch is a Starch
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!
One important note on using flour as a thickener vs the straight starches – flour-thickened sauces are translucent/opaque, whereas cornstarch-thickened sauces are more transparent. Sometimes this doesn’t matter, but sometimes it’s an important aesthetical consideration – for instance, I have a real problem with transparent meat gravy!
I’ve read before that this is a consequence of the proteins in flour, but I don’t know if that’s true. Got any wisdom for us here, Joe?
I believe it has to do with particle size, Nicole! The bigger bits of endosperm reflect light rays back toward the eye instead of letting them pass through. I need to check that of course…
And I’m with you on clear gravy. Nasty.
– Joe
That’s Thanks and this is awesome! I hadn’t considered the heat aspect as to what would/could/might work with starches… Gives me stuff to think about. Thank you so much!
My pleasure, Mark!
– Joe
“Cornstarch (corn flour)”
I’m increasing seeing these used interchangeably, and am wondering where this comes from. In my pantry, I have both cornstarch and corn flour. This corn flour came labeled as such, and is just corn that has been ground to a fine consistency like wheat flour.
Is cornstarch being called “corn flour” a global regional variation?
Hi Tom!
I frequently add (corn flour) because that’s what American cornstarch is called in Britain (and perhaps Australia/New Zealand) though I’m not totally sure. Some people in the States call finely milled corn meal “corn flour” and I think it’s really confusing. Corn meal is equivalent to whole wheat flour in that it has endosperm (starch), germ and bran in it. American cornstarch is just the pure starch, very finely milled so it disperses easily.
Does that help or just confuse things? 😉
Cheers,
– Joe
All one word Joe. Cornflour, not corn flour. And oddly enough, in New Zealand it’s made from wheat. “Pure wheaten cornflour” is a prominant bit of the label on our most common brand.
Wild. Thanks, Bronwyn!
– Joe
Perfectly clear, Joe.
I quess that Bronwyn’s info about “wheaten cornflour” in New Zealand refers us to the difference between American corn/maize, and the non-American definition of corn as “a single grain of a cereal plant,” or “Any of various cereal plants or grains, especially the principal crop cultivated in a particular region, such as wheat in England or oats in Scotland.”
What about xanthan gum? Not a starch, but how do its pros and cons stack up?
Xanthan gum??? That’s one of my all-time favorite ingredients!
http://joepastry.com/2010/geeks_s_corner_the_miracle_of_xanthan_gu/
It’s amazing stuff, really. It’s technically a hydrocolloid, which is to say a substance that disperses into another substance down to the microscopic level. It works just fine for pudding. You can add it right in and it gels without being heated — and once it sets up the gel is almost totally stable in the face of both acid and heat, so it won’t thin out again should you boil it. NO wonder its such a hot item in the food industry. It can do just about anything.
Great question, Evan!
– Joe
I have been a frequent user of various starches. Often, when thickening soups, sauces, etc, I would mix the different starches to achieve the desired consistency and effect. I often employ potato starch, wheat starch, tapioca starch, and cornstarch.
I do see in the markets many other variant starches. Varieties include sweet potato starch, chickpea flour, mung bean starch, water chestnut starch, and acorn starch. And I have never used any of these. Do you know their various properties and possible uses and application?
~Lucian
Hey Lucian!
I wish I had experience with some of these more specialized starches, but I don’t. This may be a good excuse for a series on the subject.
Thanks for the note!
– Joe
Thank you for great info. What do you think the advantages and disadvantages of wheat starch(Asian grocery)? Looking forward to learn from you, thanks.
Hello Hoa!
As far as I know I have not worked with Asian wheat starch yet. If I recall correctly it is very finely ground. Perhaps I need to do a new series of posts on starches and thickeners.
– Joe