I don't like to throw anything away. When you brew beer you end up with grain, hops and - to a lesser degree - yeast. All three are pretty much useless to you; at least from a brewing perspective.
I've made bread with spent grain before and achieved some half-decent results. Spent yeast and hops, on the other hand, I've never found a use for. Commercially, the yeast trub that settles out after primary fermentation will have fresh wort pitched on to it so that fermentation can begin all over again. Just because a beer has reached final gravity, it doesn't mean that the yeast is dead and unable to ferment any thing else. With this in mind, I carried out an experiment using yeast trub to leaven a loaf of bread.
My last homebrew beer used Safale 04; an English ale yeast strain. When primary fermentation finished, I racked the beer off into a secondary tank so that it could be dry-hopped. I collected the yeast trub from the bottom of the primary tank and stored it in the fridge, in a sterilised jar, until it was needed.
Baking bread is easy. Baking very good bread can actually be quite difficult. For this experiment I used: two parts white flour, one part brown flour, one part yeast trub and some salt. Combine all the ingredients with enough water to make a smooth dough and then knead for roughly ten minutes. Leave the dough to prove until double in size, knock back, shape and leave again. When the loaf is double its original shaped size, bake in a very hot oven for ten minutes, then lower the heat and bake until cooked through.
I had a slight concern that the yeast might have died. I kept it in the fridge for about a week before using it and hadn't really given it any time at ambient temperature to warm up. This proved to be completely unfounded. The yeast took off like a rocket, leaving the dough double in size within about twenty minutes. Having shaped it and moved it to a loaf tin, the yeast was working so quickly I could practically see the dough rising before my eyes!
The loaf baked very well indeed and had a nice golden, crispy crust. The texture of the bread was also very good; very light and airy with even distribution of the gas throughout. Unfortunately though, the taste couldn't quite live up to this. If you've ever experienced it, imagine the smell when you peer into a fermenter during primary fermentation. That sweet smell of yeast that's carried to you by over zealous CO2, eager to leave it's birth place and enter the world. That's exactly how the bread tasted. That taste, followed by an incredibly unpleasant metallic bitterness.
So in conclusion, a fun experiment but an end result that wasn't a complete success. I might try this in future with different yeast strains and with different ratios of yeast trub to flour. Anyone else had success doing this?
I know the recipe steps above are vague but this entry is more about the experiment than a walk through on how to bake bread. If anyone wants more detail, and doesn't just automatically look elsewhere, I'll happily post it.