Warning: This post definitely falls into the category 'singular obsessions!'
Like most people, I've gone through life unable to identify very many activities of which I could say that I was a bit of a dab hand and that I actually pursue, but weirdly enough baking is one of them. I can't recall when I started, but I did, and I've continued to this day. Generally, if I feel like eating bread, I'll bake it.
Moreover, I tend to know quite a bit about the whole bread thing: I have read histories of bread pricing (yeah, I know!) and the like. Generally the rise of the modern state can partly be traced in how the powers of millers and consumers of bread was regulated. This was crucial question for the rulers of early modern Europe. If they got assizes wrong, there would either be food riots or millers' revolts. But once prices were fixed tensions over how bread was to be made shifted to how weights and measures should be maintained, which required a state policy on what a loaf of bread should weigh which required a state policy on what weight actually is.1
Anyway, I was throwing together a couple of loaves on Tuesday evening when I was struck by a recurring question. Why do the some baking traditions rely upon yeast baking and some upon bicarbonate of soda baking?
Well, if you've made it this far you'll probably indulge me a little bit further...
OK: a little background. First, the yeast/bicarbonate thing is a relatively new issue, again to do with modernity. We can generally guess that bread, for the first 50,000 years or so would have been made to rise, thus tasting better and not ruining our teeth, the old fashioned way. Which is that periodically a batter would have been left in the open to pick up naturally abundant yeast from the air. Generally though, there would always be a little bit of bread proving away. When it came to be thrown on the fire, a section would be put aside, mixed with more flour and would provide the basis for the next loaf. There are still traditions, in Continental Europe and the USA, of having that sort of continuity: I read somewhere about a so-called friendship loaf that was a century old or more. Anyway, the basic point is that all bread was this kind of sourdough bread until the 19th century, when people could buy commercial yeast or bicarbonate as it became available.
Second, as anyone who bakes knows, the great thing about bicarb is that you can throw a dough together in about 10 minutes and it goes straight into the oven. The bad thing, which is slightly irrelevant if you have a big family, is that the bread is stale within the day. Properly made yeast bread, on the other hand, lasts for up to a week. So there are real efficiency gains to be had with yeast.
Third, bicarbonate of soda works because, when mixed with an acid, it releases CO2. In Ireland, the traditional method is to bake soda bread with buttermilk: literally the acidic milk left over after butter has been churned.
Perhaps you know different, but I've only heard of two places that adopted a large-scale tradition of soda bread baking, They are, and this is a little strange, Ireland and Bulgaria. Two countries on each end of the European continent that adopted at least similar methods for baking, while most places in between adopted yeast baking. Anyway, here's a couple of theories as to what the reason for this might be (and I'm pure guessing here: if you think you know better please let me know):
1. I'm wrong. Perhaps bicarb baking was prevalent in Europe for a while. It's not time consuming, it uses up valuable milk products that might otherwise go to waste. Perhaps it's remaining as tradition in some places only has more to do with volk cultural movements, or with a more recent relationship with peasant cooking methods than more industrialised regions, where people abandoned such methods before the idea of heritage lent them value.
2. Perhaps until recently certain areas had little access to mass produced yeast, which tends to require special storage, but had access to bicarb, which is more robust (although it would have to kept dry: no mean feat in Ireland!).
3. It has something to do with soil conditions. Soil certainly has a bearing on what wheat will grow. Northern Europeans tend to use rye, whereas the Romans used spelt a lot (not strictly a wheat: it's a grass). Perhaps certain sorts of wheat were more amenable to bicarb. Yeast requires a pretty narrow range of conditions to grow very well, one of which is a high gluten content in the dough, so maybe the Irish and Bulgarians grew wheat that didn't work well with yeast. I have to say that this is a little implausible, but it relates to the far more plausible...
...4. Milling habits. This question was kicked off by my wondering about why (when I bother with top class flour) I prefer using English flour (Dove's Farm, BTW) to the Irish flour (Abbey is best, to my mind). Well the reason is that Abbey is a far rougher flour than Dove's Farm. It's designed for soda bread, so the whole grain is in the flour. Yeast finds that difficult, since it can't work on the gluten in a very mealy dough. I wonder if, instead of Irish flour being designed for the local soda bread baking habits, the habits were originally designed for the flour: if Irish (and perhaps Bulgarian?) mills tended to make rougher flour. This might be because bread was the preserve of the poor, so they wanted every bit of grain in the bread (unlike the rich who traditionally showed off by buying white bread, with most of the grain removed). Or it might just be one of those things.
Anyway, if you haven't given up in boredom, and you have an alternative theory, let me know. Indulge my obsessions!
1By the way, one of the best brief histories of bread is in Elizabeth David's English Bread and Yeast Cookery. The whole weights and measures thing is mentioned in James Scott's Seeing Like a State, but the best history of it is a book by a Polish historian called Witold Kula, called Measures and Men.