Yeast Sugar Consumption

[scott123]

I am in the process of developing a low carb bread. Subbing for flour is a little tricky but I think I'm making headway. The lack of nutrients for the yeast to munch on is a daunting challenge though.

The trick is to add just enough sugar to the dough for the yeast to survive but not enough to leave much residual sugar in the finished bread. Can this be done? I've read somewhere that yeast can subsist on table sugar but do much better on a simple sugar like malt or the type of sugar that flour is broken down into.

I guess I could make 12 different batches of dough, add sugar in small increments to each and see how much leavening I get, but I was wondering if anyone knew a ballpark minimum sugar requirement for yeast.

[KyleW]

What are you using in place of wheat flour?

[Anneke]

I believe it can be done with virtually no sugar. I remember reading about a yeast experiment. The purpose was not to evaluate if yeast could grow without sugar, but rather to evaluate the destructive effect of salt on yeast. Two batches of yeast were therefore prepared, one with sugar, and the other with salt. Surprisingly, both grew successfully. The only difference was the speed of growth. Bottom line: we may be overestimating the role of sugar with yeast.

Good luck with your experiments.

[Headless Chicken]

Originally Posted by Anneke

I believe it can be done with virtually no sugar. I remember reading about a yeast experiment. The purpose was not to evaluate if yeast could grow without sugar, but rather to evaluate the destructive effect of salt on yeast. Two batches of yeast were therefore prepared, one with sugar, and the other with salt. Surprisingly, both grew successfully. The only difference was the speed of growth. Bottom line: we may be overestimating the role of sugar with yeast.

Good luck with your experiments.

Interesting, would you have any readings on it or online links?

[scott123]

Originally Posted by KyleW

What are you using in place of wheat flour?

Well, I need to provide the yeast a gluten framework to leaven, so I'm using some wheat protein isolate which has almost no starch. Along with that probably some almond flour which has a very neutral flavor and starchlike consistency. After that I'm not absolute sure. Maybe whey protein isolate. Maybe some form of fiber. A lot of low carb baking mixes use soy protein because it's cheap, but I'm trying to stay away from it because I dont' like the flavor of soy. I might use a very small amount though. An almond flour/wheat protein combo is just not enough to mimic wheat flour. I need something else.

[scott123]

Originally Posted by Anneke

Two batches of yeast were therefore prepared, one with sugar, and the other with salt. Surprisingly, both grew successfully.

That's fascinating. I'm curious, were these two batches just yeast in water? One with water and salt and the other water and sugar? No flour involved?

[KyleW]

I did a little poking around and found an interesting "Atkins" site with info WPI. Seems like t should work. The site has a and in one thread there is a post from a moderator about the properties of WPI . She says that in addition to the nut flour, oat flour is a good addition.

[Anneke]

Originally Posted by scott123

That's fascinating. I'm curious, were these two batches just yeast in water? One with water and salt and the other water and sugar? No flour involved?

Correct.

Here's the link: http://www.chefsimon.com/levselsu.htm (sorry, it';s in french. But it has pretty pictures...)