Sourdough is the traditional way of making bread – without adding yeast to the dough. To make sourdough, the ‘wild’ yeasts found naturally in the flour are cultured (similar to when you make yogurt) until there’s enough to make the dough rise. The whole process takes a while, which means the dough has time to ferment – giving it all sorts of super powers, as well as it’s distinctive sour taste.
Sourdough bread has several nutritional benefits over other breads, including better iron absorption and a lower glycaemic index. It’s all thanks to that long fermentation process, when the yeast and other beneficial bacteria break down the starch and sugars and remove phytic acid (a substance in grains that inhibits iron absorption).
That’s not all that happens, lactobacilli bacteria also turn the sugars into lactic acid, which stops other bacteria and fungi from ‘invading’. So sourdough bread keeps longer than quickly proven breads, without any need for artificial preservatives.
People have been making bread this way for millennia, ever since some ancient Egyptian noticed his (or her) bread tasted better when he left the dough longer. It’s only in the past few centuries that people realised they could make bread quicker by adding extra yeast, and only in the past few decades that people realised that quick bread is not neccessarily good bread.
So slow it down a little to enjoy your loaf!