Tuesday, September 10, 2013

Reader's Questions: Weight vs. Volume, Convection vs. Standard in Gluten-Free Sourdough Bread

I occasionally receive questions about measuring ingredients using weight rather than volume in gluten-free sourdough breads. Using weight is considered by some to be more accurate and is used by most professional bakers and cooks. I bought a scale to learn about using weight and found that the weight of finely ground rice flour is different than of coarsely ground rice flour. 

I bought different brands of rice flour and found they were all slightly different weights. How could I possibly give an accurate weight measurement when people purchase different brands that are also different grinds thus will be different weights? 

I had already realized that readers were having varying types of results using fine commercial flour while I was using slightly coarse home milled flours to develop my recipes. I spent a couple of years learning and working with the differences. 

I put that info into my book and updates so people could learn to compensate for those differences. I would love to sort out the proper weights for all the recipes but probably won't be doing it any time soon.
Meanwhile, a reader had some specific questions about measuring by weight that I was able to answer.
He also had questions about using a convection oven rather than a standard oven. We had a few back and forth emails over a few weeks, testing and sharing information. Have a read:

C.L., Northern Ireland:
Hi, Sharon. I must say how much I am enjoying your book, it is really interesting and informative. I have been very encouraged to have a go. I am in the middle of making Sourdough Bread #2 new (brown rice-quinoa), and a couple of questions have occurred to me.
In the UK, we measure ingredients by weight instead of volume. I have been using 250g for one cup for water, and 130g for flour. These measurements seem to work quite well on other gluten free recipes I have tried, but do you know the exact conversion between cups and grams for your recipes?

Glad you wrote, C.L.!  I just happen to have a gluten-free sourdough thick starter fermenting now! It is made with rather fine commercially milled brown rice flour.

The ratio of flour to water is 2:1. 
Here are the weights I came up with:

1 cup water = 228 g
1 cup brown rice flour = 138 g

C.L.: And when you say to add four cups of 'new thick starter', what weight in grams would you think it would be? I used 1000g but it seems a lot. 

Sharon: I believe 1 cup of thick starter would equal 230g, so 4 cups would be 920g, somewhat less than the 1000g you arrived at.

C.L.: I am using a convection oven. My wife says I need to reduce the oven temp by 10°C (about 25°F); does that sound like the right conversion for sourdough, or would I need to shorten the time in the oven as well?

Sharon: I have not used the convection feature in my oven yet. Each loaf is so precious and I don't have the courage to risk losing a loaf. I have more than enough failures already. I think your wife is correct to reduce the temp by 10°C. You may need to reduce the baking time as well, but I'm not sure by how much. 

Keep in mind that gluten free breads are high moisture breads and need longer rather than shorter baking times. You may need to test the bread often for doneness. If you arrive at a good baking time using a convection oven, please let me know what it is.

C.L.: Here is a picture of my first gluten-free sourdough loaf. I had already started this before I got your email with the weights.
Using my convection oven, I cooked it covered for the first 40 mins at 140°C (275°F) and then uncovered for the next 1 hour and 10 mins. I used the temperature probe and when it registered 99 deg C, I took it out. I read somewhere that if the loaf temp reads  99°C (210°F), it is cooked, but using the probe, you can tell if it is still too damp - just like using a skewer.

 Was it successful? You have to understand that I am now coeliac and before now had never eaten sourdough bread of any sort, so I have nothing to compare it with. I think the crust is really quite bitter but the main body of the bread wasn't too bad, quite a nice texture with an unusual but not unpleasant taste. Is this what it’s supposed to be like?

Sharon: The bread looks really good for a first try!!! The density and tight crumb suggests it has a bit too much water which would confirm too much water in your first experiment. The recipe makes a somewhat dense bread but still slices well and holds together.

I'm surprised the crust was bitter, however quinoa can have a bitter taste if you are not used to it. Just speculating here… the fan in the convection oven may have dried out the crust a bit perhaps concentrating the bitter taste. On the good side, it seems the convection gives some nice browning to the crust.

C.L.: The loaf is a bit scrappy at the top as it rose much higher than expected, so it was a bit of a session trying to stop it running over before it went in the oven. I used a non-stick metal 9" x 2 ¾" x 4 ½" loaf tin.

Sharon: The fact that it rose so much is good news! It means you are creating a really active starter! Good Job! The extra water in the recipe would increase the volume possibly causing a spillover. The amount of batter may be a bit too much for your loaf pan size. Sometimes I line the pan with parchment paper and leave the paper high on the top. The high paper creates a “collar” that can often hold the batter in place as it rises.

C.L.: I was reading more of your book and was thinking of trying the gluten-free sourdough tapioca bread - I think it was described as a 'sandwich bread', and I think this is really what I am after but am open to trying anything. I feel quite amazed that I got any result at all, first time round.

Sharon: The tapioca bread is a milder bread and has a nice spongy quality. I think you will like it. It was a commissioned recipe for a young boy.
C.L.: I have been trying the tapioca bread. I have had lots of success and made and eaten quite a few loaves. I think it’s terrific. The texture is brilliant. I took your advice and reduced the water a little.I cooked it at 170°C (340°F) for 1 hour and 10 minutes.My wife really liked it too and she isn’t coeliac!

Sharon: It's great when non-coeliac people appreciate gluten-free bread. My non-coeliac husband prefers my bread because it's so substantial. Thanks for sharing, C.L., and keep us posted about your future bread baking!