Sourdough Science Saturday

My starter is a little over two and a half years old and as I alluded to in my previous post I’ve baked about two hundred and fifty-ish loaves of bread with it, pre- and during pandemic.

You would almost think I would understand it better.

About an hour ago I pulled my Thanksgiving loaf from the oven and it turned out great.

All around, I followed my basic twenty-four hour prep-and-proof plan, the process I’ve been fine tuning for years even before this starter, and which works for me fairly consistently.

Only it sometimes doesn’t.

Like this summer.

This summer we had a heat wave for a solid month where the temperatures outside rarely dropped below twenty-five degrees at night and routinely stuck in the mid-to-high thirties during the day. Also, it rarely dropped below twenty-five degrees in our house (including the kitchen) which was a nightmare, the waking kind, because I could hardly sleep in those conditions.

All the bread I baked during this month flopped.

Poor rise. Dense crumb. Edible … but not enjoyable.

And at the time I got it into my head that the heat was putting my yeast into some runaway proof and I was missing the window to bake it and get a good loaf.

However.

I’ve had a few months to think about this, and my nineteen degree kitchen (where I proofed today’s loaf to within one standard deviation of perfection) only added another layer of evidence to my theory.

“You’d think the yeast would have liked the heat.” Went the conversation with my wife. “But I think my yeast aren’t loving it.”

Not all yeast are created equally, after all. In fact, there are fifteen hundred known varieties of yeast, and the yeast that come in the little envelope from the grocery store may have very little lineage in common with the yeast I caught in my kitchen two and a half years ago.

The yeast from the store are bred to grow consistently, quickly and thrive at warm temperatures.

I’d be willing to bet that whatever yeast I found thriving in my kitchen air and trapped in my starter probably prefer, say, a dry central Canadian climate and do quite well in my nineteen degree kitchen. Wouldn’t it make sense, after all, that the most common yeast floating around my house were probably plentiful enough to be caught because they actually favoured … preferred … had maybe even adapted to … the conditions of my house?

So, back in June when my house was eight or nine degrees warmer than normal, those nineteen-degree-loving yeast … well, they made some garbage bread.

And today, when my thermostat is regulating the house to optimal conditions for both me and my yeast … well logically they made a loaf of awesome bread.