Q & A Thursday: the nutrient content of sourdough bread?
Posted by kathryn in Grains
The last question in today’s Q & A Thursday is from Antti-Juhani:
what is the effect of sourdough fermentation on the macronutrient content of a bread dough?
Really, really, really good question . . . but one I’m not able to answer.
So I’m wondering if anyone else can help?
What I do know about sourdoughs:
- Sourdough bread is made with a starter culture, which is a blend of bacteria and yeast. This culture reacts with the starches in flour and water to produce gas. The gas is trapped as bubbles in the dough – making it rise and form the texture we know as bread.
- Sourdough cultures do impact the texture and taste of breads.
- They can also affect the bioavailability of some nutrients.
- Sourdough cultures affect how we breakdown and absorb carbohydrates: they have a lower GI than yeasted breads.
- The Australian food tables do not differentiate between yeasted and sourdough breads in their nutritional breakdown.
So, while sourdough might affect how we breakdown and use macronutrients, I’m unsure if it changes the overall levels of protein, fat and carbohydrate in the food stuff itself.
So I’m throwing this one open to you. Does anyone have any further information on the effects of sourdough fermentation on the macronutrient content of bread?
07 May, 2008
Comments
The reason I asked the question is that the yeasts and the lactobacilli obviously consume some of the carbohydrate content of the dough – but how significant is this depletion of carbs?
The main difference between commercially yeasted bread and sourdough bread is (apart from the obvious) that sourdoughs are fermented longer. My doughs generally ferment from three to twenty hours before baking.
I suspect it’s only a tiny amount Antti-Juhani – the critters are just not that voracious. From the research I’ve done I think the macro-nutrient content of your bread will be more impacted by the type of flour and how much fibre it contains.
But I’d like to know if anyone else has information on this?
If one forgets to feed ones culture for days and keeps it in room temperature, the critters will starve. Or so I am told – I have not tested it myself. That suggests it’s not quite a tiny amount (though it could be a geometric progression, with the really large amounts of eating happening at the end).
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