Xbeeriment with sourdough yeast

Xbeeriment with sourdough yeast

I love to experiment with food as is clear from my other blogs. A couple of weeks ago this turned to beer. Here’s how it unfolded. I’ll also apologize in advance here. Brewers are going to know what I am on about here. The rest of the world not so much.

A month previously I was making a stout, and it stalled out at 1.024. If you’re a brewer you know that this is not good news. Your yeast stopped doing its thing, well before all the sugars were fermented. Once that happens there is not a lot you can do about it. But I did. I pitched some sourdough starter in it thinking ‘what have I got to lose?’ It turns out plenty. The sourdough did a great job of fermenting the brew right down to 1.003 which means a that just about all of that sugar got fermented. However on the way, it also changed it to vinegar. Perhaps someone could be generous and say that I now have a sour stout. But really. Don’t think so. As beer vinegar its good – all 6L of it.

But I wanted to explore further what the effect of sourdough would be on fermentation if I used it uniquely. I had no idea what it will turn out like once its been in the bottle for 6 weeks.

I decided I would make a brew and split it in half to pitch the yeast. One would get SD and the other would get sourdough. As for the grains, truth be told I was at the end of my supply and needed to use stuff up. That is why the quantities are a little strange

Here is the recipe that came about:

This is for a 6 litre batch

11 litres of water

Grain bill

.95kg Pilsner

.81kg Maris otter

.2 kg White wheat

50g Caramel 20

50g Carapils

Hops

14g Tettnang (17.9 IBU)

Yeast

  • ½ the batch received sourdough: 200g very active SD yeast was pitched in 400g 1.035 wort about 10 hours before pitching
  • ½ the batch received 2.4 g of Lallemand Belle Saison, hydrated for about 30 minutes in RO water.

Method

My process was pretty simple BIAB:

  • 11 Litres of water in a 20L tun
  • BIAB full body for the mash. Strike temp: 74.4C; Mash 68.9C 1 hour; mash out 15 minutes to 75.6C
  • Add Tettnang at the start of the hour boil
  • I should note too that I’ve come to like using a fairly heavy boil which yields a crazy high OG, and then I use ice cubes to bring it down to the desired 1.060 OG

Fermenting

Saison is on the left, Sourdough is on the right

Usually I use the same 11 L container I measure and pour the initial water from as my fermentation vessel. This time, I used 2 gallon cider jugs. The SD refresh was pitched in one and the Belle Saison in the other.

Bottling

Here are my observations at bottling:

Belle Saison Sourdough
OG 1.060 1.060
FG 1.010 (ABV 6.6) 1.011 (ABV 6.5)
APPEARANCE Darker, clearer, a lot more trub, bits of flocculant on the top Lighter, cloudy, more settled, a lot less trub
TASTE A good slightly hoppy ale – slight floral and spice notes A more neutral ale but there is a hint of sourness (which makes sense – SD has lots of lactic acid bacteria)
Total volume at bottling 5.75 L 6.25L (there was that much difference in the trub.

Apologies for the blurry pic but you can see they both dried out nicely.

As you can see there’s a lot more trub in the Saison brew.

Some interim conclusions and next steps

  • I’m really delighted both brews worked themselves down to 1.010. I must be doing something right.
  • If my beer yeast were to get destroyed, I’d still be brewing
  • I’d like to see the effect of changing my hops – what would a low IBU and a high IBU similar experiment yield? I have heard that hops tend to destroy the LABs so perhaps really low IBU may result in a sour beer

I will finish this blog in 6 weeks when I taste the final product!

2 thoughts on “Xbeeriment with sourdough yeast

    • There is no question that the SD yeast brought it all the way down – both came out at 1.010 or thereabouts.
      There was definitely a taste difference: the SD yeast had a hint of LAB tang to it, but just a hint. The huge difference was that the SD was way overcarbonated. Whenever I pour one I have to do those various tricks to direct the exploding beer into a container so I don’t lose it. I’m curious as to why that is because I used the same amount of priming sugar in each, and both were dried out to the same extent.

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