When I run my sourdough bread baking courses, I often get asked criptical questions from my curious students. The answers to some of the questions like: 'Is sourdough bread gluten free ?' initially seem very obvious, but strangely enough when you dig a little deeper the answer is not that clear cut.
So, first of all to satisfy your curiosity to know whether sourdough bread is gluten free, well, of course it depends on what type of flour you use! Since it's very difficult to bake a true sourdough bread from completely gluten free flour, traditional sourdough breads are not gluten free.
The gluten is what gives the bread the structure, without it it would be really difficult for the bread to rise and keep it's shape.
But sourdough bread is traditionally baked with rye flour, which naturally has low gluten. So, if you are very sensitive to gluten, this is still not a bread for you.
But if you are just looking for easier bread to digest and eat slightly less gluten, then rye sourdough bread is a good option (as oppose to say, traditional white bread).
The reason, why some people claim that sourdough bread is gluten free is because if sourdough bread is made in the traditional way (with a long fermentation process) the acid, that's produced, break down some of the flour gluten, making the bread easier to digest.
That's why people who have mild gluten intolerance can sometimes eat sourdough bread without any problems. But, I should also point out that, such sourdough bread is usually home made or bought from a traditional baker who specialises in sourdough bread baking. Commercially produced sourdough bread is rarely made in the same way as traditional sourdough and often contains yeast and other raising agents. It's also left to prove for shorter period of time, which means that the process is not long enough for it to break down any gluten.
So, what happens with the gluten, whilst the sourdough bread is fermented?
The traditional sourdough bread fermentation produces acids, which help to break down the gluten in the flour. This is because acids prevent mould and bad bacteria growth in the bread dough. The fermentation process also dissolve proteins, by producing protein ezymes, which help to break down the protein molecules. This makes the sourdough bread much easier for our bodies to digest. Since gluten is mainly protein, this is why true sourdough bread is much easier to digest, but it doesn't mean that sourdough bread is completely free of gluten.
The chances of finding such a sourdough bread in a commercial bakery is very slim and even if you buy your sourdough bread from a traditional baker, you should still bear the following in mind.
Every baker is different and all have their favourite ways of making sourdough bread - some use 24 fermentation process some 48 hrs. Some might use rye flour as the main ingredients, but you will also find white flour sourdough. Because non-commercial baking is not particularly controlled, each bread batch might have slightly different fermentation time depending on time of the year or how cold or warm is the bakery or kitchen. Most sourdough bread bakers will also be a traditional bread bakers, which means that there will be normal gluten flour present in the kitchen and there will be certain amount of cross contamination in ovens, baking trays or even utensils.
The study that caused a bit of a stir in a gluten free world.
In 2011 a small scale study was conducted into the effect of sourdough and gluten intolerance and published in Clinical Gastroenterology and Hepatology Chronical. The aim of the study was to look at types of wheat - gluten bread that would be suitable for people with celiac disease. The study's results were interesting, but since the group sample was so tiny (only 13 people took part and only 11 actually completed the research) the results can't be really applicable to wide audience. The participants in this study were people with celiacs disease, who were currently not experiencing any difficulties as their condition was fully under control.
The group was split into 3 groups and were given different types of wheat bread to eat for 60 days. They were asked to eat 200g of bread each day. For us, lucky enough not to suffer with gluten intolerancies, I should also add that 'gluten-free' is considered anything below 20 ppm (parts per million).
So what happened?
Group 1 was given regular bread with over 80,000 ppm of gluten. Not surprisingly, 2 out of 6 people in this group had to leave the study as they become quite ill, from the high amount of gluten. All participants in this group had adverse effects based on follow-up blood and biopsy results.
Group 2 had just 2 participants. Their normal wheat bread was hydrolyzed, which was done by breaking down the protein with the use of fermentation with sourdough lactobacilli organisms and other fermented foods. This ment that the gluten content in this type of bread was just 2,480 ppm. Although this was much better type of bread for the participants to eat, they still had a negative reactions to it.
Group 3 had 5 participants. The researchers managed to develop a bread that was fully hydrolyzed and containing only 8 ppm gluten. The participants in this group didn't notice any ill effect from the bread they were eating, which was also confirmed with follow up blood tests and biopsy results.
Although this was a worthy study, the fully hydrolyzed bread for the group 3 was prepared under strict laboratory conditions, which means that even the best traditional sourdough bread from your local baker won't be comparable.
So, there you go!
To sum up, traditional sourdough bread is much lower in gluten, but unless it's made fully from gluten free flour, the chance are that it's not suitable for people suffering with celiac condition. If you have a mild intolerancy, I'm sure you alredy know what is best for you personally. Some of my gluten intolerant friends are OK with small amounts of home baked sourdough bread, but I know that some don't even risk that.
There are of course gluten free breads available, even sourdough bread, so it's worth searching in your local area for gluten free baker.
Until next time - happy baking!