You do not fully understand a type of flour before making a 100% loaf of that flour. I like to combine flours in my bread but to estimate what would be the consequence of each flour addition you need to have a good knowledge of how each flour you use impacts the final bread.
This is why, I baked this 100% spelt sourdough bread, to share with you how this flour behaves.
Spelt is a cereal, very close to wheat that has not been affected too much by industrialisation. The spelt grain is covered by a tough and thick hull. This one protects the grain from insects and diseases. Pollutants and pests are also less effective for this cereal. This is an ancient cereal, and we could consider that we are eating almost the same one that our ancestors were eating.
In recent years spelt gained a lot of popularity especially as an alternative to wheat. Keeping in mind the advantages of the hull, spelt is more organic. Spelt contains more proteins but less gluten. It is not only less gluten but its quality is also poor. The balance between glutenins and gliadins of the wheat is for spelt disturbed. It contains more gliadins that make the dough super stretchy and is low in gliadins that makes the dough less elastic. These are the factors that influence how a spelt dough behaves. Comparing to the wheat dough, it is soft, stretchy, sticky and it is difficult to build the structure inside. When the quality of the gluten network is affected, it is a challenge to trap the CO2 bubbles inside. More than this, spelt flour has fewer sugars, so less food for the yeast bacteria to feed. This means that there will be a lower degree of fermentation that will result in smaller gas bubbles.It might look that there are a lot of disadvantages of using spelt flour instead of wheat but there are good reasons why people prefer spelt over wheat.
The first one is that a lot of people who are gluten or wheat sensitive report that they tolerate much better spelt bread than wheat bread. The explanation might be that the gluten in spelt is different from the one in wheat. It is more water-soluble and it is broken much easier by the body. It is then easier to digest it. Another aspect is that it contains a lower % of phytic acid who is an anti-nutrient because it reduces the absorption of minerals by the body. The minerals seem to be in higher levels in spelt than in wheat.
But please, take into consideration that I am not a doctor either a scientist. I tell you here what I learned from studies and articles. The best is to consult a doctor if you have wheat/gluten sensitivity. However, keep in mind that spelt contains gluten so it is not for people with celiac disease.
I also read articles and studies swearing on the fact that spelt is the most miracle flour you can get. I've read others saying the contrary, that has nothing more special than wheat. But health and diet is not my area of expertise, I want to focus here only on how spelt affects bread making. One thing is sure, spelt flour is different from wheat flour.
With the above characteristics, bakers need to adapt their methods to get the best out of the spelt flour.
The first thing to keep in mind is that the fermentation cannot be extended up until the dough doubles in size. The fermentation needs to be stopped at about a 50% increase in volume. Higher than 50% it looks like a trap, the loaf fell onto itself in the oven. I've tested this a few times and always the same result, the bread got flat. You might want to use tricks like baking the bread into a pan and in this case, you can extend maybe to a 55-60% increase. I wanted to bake this bread freestanding to learn its limits. You also need to understand that each spelt flour is different, so you need to run your own tests with every flour source/brand. Whole spelt flour has other limits of fermentation and hydration.
To conclude, what works for me and my type of flour you also need to test for your case. Take away the basics and find your own "figures"/limits.