I've been a dedicated sourdough bread baker for years. I use long fermentation times, approximately 18 hours at 67 degrees (depending on flour type) and very long (36 to 48 hour proofing) at 38 to 42 degrees. It is my understanding that the long fermentation and proofing times is what makes sourdough so digestible and tolerated by those that suffer from store bought bread. Long fermentation digests the gluten turning into easily digestible proteins (amino acids).
Common store bought bread is often done in 3 hours from start to finish. Yech! Not good. Not to mention the variety of dough conditioners and other such nonsense that is added to get the product finished in such a short time. The so called gluten intolerance that is seen today is a result of bread products that are not properly fermented, unlike the old days. It's a real thing for many people, but I suspect that if they ate some of my sourdough bread they would not suffer any ill effects. I have seen this with many friends of mine, so I know it's true.
I use a wide variety of flours including hard wheat bread flour, soft wheat Italian '00' and '0', semolina, old wheat varieties such as Kamut, and an early form of wheat called spelt. I have excellent results with all of them and have spent countless hours developing a feel for my dough and where it is at in its fermentation process and what step(s) are needed to ensure an excellent and I mean excellent loaf of true sourdough bread.
My ingredients are: flour, purified water by reverse osmosis, pure white Spanish sea salt, and sourdough starter. My starter is old and healthy. There is nothing better than a simple and pure loaf of sourdough bread. Especially if I made it.
All temps are farenheit.