Friday 15 March 2024

Mexican Lager - BrewZilla Brew Day

It seems that lately we've been having at least some kind of problem our set back every time we brew a batch of beer. Well, this one was no exception, and whilst the problem we encountered ultimately wasn't a huge deal, it certainly could have been a bit worse, and gave us a timely reminder that making beer can sometimes be dangerous. Read on to find out more about what happened.

Starting out with our grain which we got from 41 Pints of Beer - it's a simple grist consisting of pilsner malt, and some chit barley malt. Check out our recipe post for all the details.

Mexican Lager's typically feature some type of corn product in addition to the base malt, which would typically be flaked maize, however we opted to use polenta (cornmeal) for this one (more info on this in the recipe post)


We also added some rice hulls to the grist as we weren't sure exactly how thick it would get with the polenta being added

We mashed in with our grains and polenta and left the grain bed to settle for 10 minutes or so, and whilst waited we took to adjusting the pH of our sparge water. In recent brews we've massively overshot the pH, making it far too acidic and leading to a lot of messing around with adding bicarbonate soda back in to raise the pH back up, then acid to lower it again to the right level, but we were determined not to do so this time, so we took to adding the final small parts of acid with a dropper instead of plastic syringe. Drop by drop we eventually got to 5.61 - close enough.

By this point our grain bed had 'settled' so we took a small sample from the top like we normally do and were surprised to see a pH of 4.66 - way lower than the expected 5.2-5.6 range. 

We always add a little bit less phosphoric acid than what Brewfather suggests as a type of 'safety net', so this was a little puzzling that we could overshoot by so much. Before we did anything drastic though we figured we'd give the grain bed a good stir, and then take another sample.

And good thing we did, with the second sample giving us a reading of 5.48 - comfortably within the optimal range we were aiming for.

We then started our recirculation of the wort through the grain bed.

Since we're brewing a lager, we want a really fermentable wort to increase attenuation for a lower final gravity, and nice, dry finish, so we're using a mash temperature of 65°C

By the end of the 60 minute mash the wort had started to clear up nicely

We started to raise the temperature from 65°C to 75°C for our 10 minute mash out period.

Next we began our batch sparging - we opted to revert for our old 'manual' sparging process using a simple jug to pour the water from our Digiboil sparge water heater, over the top of the grain bed.

Everything was going fine, but after pouring through most of our sparge water the flow rate really started to drop off, so we started stirring the grain bed in the raised position you can see in the photo above. 

And this is where things went wrong. Whilst we were stirring, we managed to move the grain basket enough so it slipped off the steel ring that supports it, and it landed back into the BrewZilla with the full force and weight of all the grain inside, which displaced a fair amount of wort (probably around 80°C-90°C) all over the floor, and our feet!

We were wearing socks at the time which no doubt helped prevent our feet from getting scolded (though it still certainly hurt!), and our epoxy covered floor sure came into it's own with everything being wiped/mopped up fairly easily - though we suspect some did make it's way under things in the garage which can't easily be moved. This was certainly a reminder to us that when dealing with hot liquids like this, some extra care is definitely warranted, so we'll definitely be more careful when stirring a grain bed whilst sparging in the future!

Needless to say, we didn't capture any photos of this period, so moving on!

As a result of the lost wort, we ended up with a couple of litres less volume than expected, with only a touch over 25L of pre-boil volume.

We did however exceed our estimated pre-boil gravity, with a reading of 1.040 (expected 1.037) - this is potentially directly related to the lost wort and some of the sparge water, but we'll take it as the silver lining for this 'cloud'.

Whilst waiting to reach a boil, we started measuring out our hop additions, as well as whirlfloc and yeast nutrients.

After an uneventful boil, we began chilling our wort using our immersion chiller. We gave the counter flow chiller one last try with this batch but we couldn't get the wort pumping through it again so we're going to retire that particular piece of equipment for now and stick with what we know works for us every time. We may even look at upgrading to a copper immersion chiller in the near future.

Our post-boil gravity reading was 1.045, a few points higher than expected which will certainly give us a nice, full strength beer.

And finally, we transferred to our Apollo Titan fermenter and left it overnight in our fermentation fridge to reach pitching temperature

This is our second batch with NovaLager yeast so we're looking forward to seeing how this one turns out

Fermentation completed in only a few days with a final gravity of 1.006 - 1 point lower than expected

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