Home   About

Monday, 26 April 2010

Bread with Spent Beer Yeast

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.


ben said...

Very interesting. Did you put any effort into separating the yeast from the rest of the trub (like this method for example)? I ask as I wonder if this non yeast trub is responsible for that metallic bitter note. At least the crumb looks very good...

Mark said...

I didn't. I just took trub from the primary and used it as is. That's a useful link though, thanks. Looks like it wouldn't take much effort to try and seperate some of the trub out from the yeast and you could be right ... the results could be very different. I think I'll try it next time I brew!

Eddie said...

Chunk, never mind about the vagueness - that's the best explanation of how to make bread I've ever read. I'm tempted to put my beer down right now and knock up a loaf meself.

On the matter of bitternes though, you know that brewers yeast absorbs (or adsorbs, can't remember which off-hand) a lot of hop bitterness? Doesn't matter how you crop it, it's bitter as hell. Brew a beer without hops and give that a go.

Mark said...

Eddie: Good to hear! I wasn't aware that yeast could do that, but it certainly would explain the final flavour in the bread.

Brewing a hopless beer sounds like a step too far just to make bread :P Next time I brew something with a small amount of hops I might try the bread again as a comparison though.

Thanks for the idea!

Rob Sterowski said...

I do this quite a lot. Did I read that right, that a quarter of the recipe was yeast? That's far too much. A tablespoonful or two should do it. Eddie is also right that yeast will absorb hop bitterness, but I find it tolerable.

Mark said...

Maybe a little less yeast would be the way to go too then. You're right, thats the amount of yeast I used.

I'd be shocked if you could tolerate how bitter this loaf was. It was bittteerr!! :P

Unknown said...

I used the beer trub to make a sourdough starter as described here: http://www.ehow.com/how_5745588_bake-bread-trub.html That, using some rye flour, and adding some brown sugar helps to neutralize the hop taste.

Scyrene said...

I used the yeasty dregs from my beer kit to make bread the other day. It rose beautifully, had a great toffee colour (with white flour), and nice beery smell. BUT it was really bitter. That nice bitterness in the ale was too much in the bread. Such a shame! People used to use the foam from the fermenting beer to make bread all the time - I wonder if this is less bitter, or if people's tastes were used to it?

Mark said...

Good to hear someone else is experimenting with things like this! Yeah, as Eddie says above, the yeast will absorb hop bitterness compounds and will drag them to the bottom of the FV. I think you're always gonna get the bitterness problem because of that (unless the beer had very little hop in it).

The other thing to consider I guess is that the bread wont have as much sweetness as the beer, so the bitterness won't be balanced out at all.

Good call on the top cropping! That yeast will (I assume) be more pure (no trub or anything else) and won't have had so much time to absorb bitter compounds from the hops. Worth a go! :)

Scyrene said...

Well we have a thing in Lancashire called a barm cake, which was just that - a bread roll made from the yeasty foam from the top of fermenting beer (although they are still sold and widely known, they aren't made that way now) - so I will definitely try when I next do a batch of beer! I hope it works better :)

Josh said...

I see this is pretty old, but I just did this as well, and am looking for more people who did.
I used the trub from a porter I made, no washing or anything. It sat in the fridge for a few weeks, I took it out and mixed it with about a cup each of rye and white flour to get a poolish going.
Just like you, mine blew up. I let it sit overnight then mixed in equal parts whole wheat and bread flour, some salt and about a tablespoon of brown sugar. I let it sit for a few hours, punched it down and let it rise again before shaping it and throwing it in a loaf pan.
Same baking procedure. Mine also had a bit of an old fermenter smell... but I thought it tasted great, it had a little bitter aftertaste, but like a beer, not bad.
If you can, Id try again with maybe a darker beer and a little sugar in the dough.
(I just read alex's post above... I agree with him)

Mark said...

Interesting to hear. Do you think it's the darker beer that helped, or the fact that the darker beer might've had less hop ... therefore meaning that less bitterness got through to the yeat sediment?

I've got a beer fermenting at the moment, you've inspired me to try this again. This time I think I'll take the yeast through a few washes though.

Anonymous said...

Did anyone try to make a starter from the trub and keep it in the fridge like a sourdough starter? That way you would only be using a cup of this for an entire loaf. It would probably get rid of the bitter flavour.

Mark said...

That's an interesting idea! Quite easy to try out to. Might have to see what happens when you try it.

tom said...

I've used Safale 04 to make bread too. But my trub was from a cider. AND I mixed some of the fully fermented cider into the bread too. Mine too expanded quickly. It was a very wet dough with white flour only. Result: pretty good. No bitter at all. But not as interesting as an aged (sour) dough. I tried again with a drier dough and somehow the yeast never went active. Not sure what happened that time.