One problem I have found in following Gluten Free recipes is that I like my baked goods to taste the way I think they should, and not necessarily the way someone else thinks they should. I wanted to be able to develop my own recipes rather than sifting through the thousands of muffin recipes on the internets trying to find one that I liked. To develop recipes, you need to know what you are working with, and I didn't. I've learned a bunch about flours since then.
When taking up Gluten-Free baking, you probably need a starch, and you definitely need a flour or two. With so many kinds to choose from, I felt like I needed to know what each was good for. Otherwise I would just be following a list someone else gave me. That is OK, as long as THAT person knew why they were using the flours they were using. It took me a long while to be convinced that anyone else knew what they were doing, either. My conclusion is that some do know, and some don't. Do I know what I am talking about? Some, and some not. Here is what I have learned about GF flours, mostly from trying the out to see what they did.
First off, there are three main divisions among gluten free flours. There are the grain flours, which are really divided into rice flours and all the other grains, and bean flours. For years, rice flours were all that celiacs could use, and sometimes I think they get included in recipes for historical reasons. On the other hand, they are often give good structure. The other grains are much newer to the scene, and are often a good addition. The bean flours are soft and nutritious, so they give you baked goods that have both of those qualities. They also taste like beans, so watch out when you use them.
The Rice Flours
White Rice -- Thanks to Chang's Oriental Market, this is the cheapest flour I have found. Put it with some Tapioca Starch, and you can save some yourself some coin. Of course, you have to spend that coin on some supplementa vitamins, but there you go. White rice flour is made from rice that has had the nutrient rich bran removed prior to grinding, and it is essentially filler. I haven't done a nutrient comparison on rice flours, so I can't extensively comment on the damage that does. I do know that you might end up with beriberi if you just eat white rice.
Aside from cost, the main advantage of using white rice flour is that it acts kind of like the rebar that you find in concrete. Rice is a hard flour, and is good at holding things up – not holding it together, you need binding agents for that. If your muffin or whatever is too soft and baking it longer doesn't help, add more rice flour. If you use too much rice flour, though, what you end up with has a texture that screams "Gluten Free!"
The other advantage rice has is that it doesn't add any flavour. Depending on the circumstance this can be a real negative, but it doesn't take too many slices of bread that taste like beans before you think that being tasteless can have its place.
Brown Rice – This is better for you, and provides even better structure than white rice flour. When I get my grinder, I'm switching back. I use 1/3 rice flour in my muffins, for sturdiness.
Sweet Rice – Also called Glutinous Rice flour (Note the i instead of the e in there). I think they call it that because it comes from sticky rice. I haven't baked much with Sweet Rice flour, because my impression is that it doesn't hold things up as well as I am counting on my rice flour to do. It does work really well at making gravy, though.
The Other Grains
Sorghum – If you don't know yet the advantages of sorghum flour, you must not actually be reading my blog. It has a good mild flavour. It is a good colour. It is good for you. It is soft, so you don't get that "Gluten Free!" texture that rice flour gives you. I've also seen sorghum flour help a little old lady cross a busy street with her groceries.
As a sorghum muffin ages, it doesn't really go stale unless you have too much corn starch in it, but the flavour does change over a few days. I think that there is some enzymatic process that breaks down some protein or other that is activated by baking. I do like to keep my muffins in the freezer, not to keep them from going stale, but to keep the flavour from evolving into something more bitter.
Millet – The only millet flour I have used is Finger Millet flour, from the Indian Store. It's purple. I am sure that there are other kinds of millet flour available, but I haven't really looked. The millet that I use as a couscous substitute isn't purple, for example. When I get a flour mill, I will try that out. I suspect that it might have some of the same advantages sorghum does, but I kind of dead-ended with the color purple.
T'eff – I have never tried teff. I don't have a good source that doesn't cost 5 x as much as other flours.
Update 4/20/2007: A reader sent me some Teff, which I now know that I like. Adding 1/3 Teff seems to make things taste more whole grain-y, like using wheat flour instead of all-purpose flour. I wonder if using too much would be too much, if you will, but you might consider trying it. A more detailed story can be found here.
Amaranth – Like teff, amaranth is expensive. Unlike teff, someone gave me some once so I could try it. Amaranth is quite bitter and nasty tasting, but in a good way. Think lemon zest or tonic water, and you get the idea. You wouldn't want to use more than ¼ amaranth flour in anything and even that might be too much. In the right amount, it can really add depth of flavour. I like it. I also like Tonic water, so some people think I'm crazy.
Another advantage to using amaranth is that it seems to bind things together, like Xanthan gum or Kudzu does. I don't know how it does this, but if you use some amaranth, you can leave the Xanthan out without everything crumbling to dust.
BuckWheat – Like amaranth, buckwheat flour can be quite bitter, but some people like it is small doses. I would sometimes make buckwheat pancakes with ¼ buckwheat to all-purpose flour, back in the old days. If you use too much buckwheat, the batter is kind of gluey and hard to work with. I wonder now if has the same kind of binding activity that amaranth has. This is something to check out.
Oats – I have seen links to GF oats that didn't cost too much. I remember them being about $2.50/lb, which isn't bad. They were just $20/lb to ship here. The deal is that some strains of oats have gluten-like proteins, and some strains don't. Sheltie Girl uses oats all the time, so she would be the one to ask about its properties instead of me.
My experience with bean flours is generally that they make your bread taste like beans. They are soft, and give a good texture. The first loaf I ever made that actually rose had garfava flour in it, but the kids didn't like it. The beany flavour fades somewhat with baking, so you really want to avoid under-cooking things. Just keep in mind that it won't ever go completely away.
People who like bean flours tout its high protein content as so much better than rice flour
Garfava – This is a trade name, like Kleenex or Xerox. If you get if from another company, it is called Garbanzo/Fava, or Chickpea/Fava, because it is a 1:1 mix of the two flours. It makes a good soft bread in one of the Gluten Free Gourmet's flour mixes, but it still tastes like beans.
Chickpea – This was how I learned that Chickpea/Fava doesn't mean chickpea or Fava. I made a cake with just chickpea flour, and it didn't go well at all.
Soy Flour – My little sister says that every chocolate chip cookie ought to have soy flour in it, for the nutty taste. Hildegard can't eat very much soy, so I haven't spent more time experimenting without soy flour than I have with it.
Soy Powder – Sometimes it is tough to distinguish soy flour from soy powder, because the terminology isn't standardized. The essential difference, as I understand it is that soy flour is ground soy beans. Soy powder is made from ground, cooked and dried soybeans. The pre-cooking really reduces the beany flavour. Whenever I am looking at a recipe that calls for soy flour, I use soy powder instead.
Lentil Flour – I found some of this in my freezer the other day. I don't remember how it tasted at all.