Wednesday, 10 September 2014

Repetition: Ordinary Bitter, Water Treatment, and Carbonation

First Beer
This weekend I brewed a version of the Ordinary Bitter I made earlier this year.  As I begin to pay more attention to the details of my brewing, I find that I'm much more inclined to return to the same recipes over and over again, tweaking the ingredients or other aspects of the process so that I get a better understanding of how all of this affects the final beer.

Earlier this summer I attempted an experiment in this spirit.  On two subsequent weekends, I brewed two identical Bitters, keeping everything the same apart from the water treatment for the mash.  I was hoping to get a better understanding of how mineral additions and mash pH shaped the flavours of my beer, and perhaps to start to work out what my own preferences were here.  Things didn't quite go according to plan, as I'll explain below---but I still feel that I learnt a lot, and I'm inclined to start doing this kind of thing more often.

The recipe for the beers was fairly simple: Golden Promise and invert #2, with additions of EKG and Fuggles in the first half of the boil, and Styrian Goldings towards the end.  I fermented both beers with Wyeast 1469, cropping and pitching from one to the next.  (Some people might be able to recognize the inspiration for this beer from this description.)  I wanted something fairly straight-forward and familiar so that any differences would be more obvious.

Chicago has pretty great water for brewing: its low in most minerals and tastes fine (to me) once its been filtered for chlorine.  The one problem is that it has fairly high residual alkalinity, which can make it difficult to hit a mash pH in the right range when brewing pale beers.  I usually deal with this by a combination of acid and mineral additions.  My aim with these beers was to work out (a) whether I had any preference between relying more on acid than minerals, or vice versa; and (b) whether higher levels of either affected the flavour profile positively or negatively.

To this end, I brewed one beer with a relatively large addition of lactic acid (5ml), and smaller additions of gypsum (3.2g) and calcium chloride (1.6g).  According to Bru'n Water, this gave me a mash with the following water profile:

         Calcium: 84.6               Magnesium: 11.8        
         Sodium 8.4                  Sulfate 106.3
         Chloride: 49.3              Bicarbonate: -44.2        
         Total Hardness: 260     Residual Alkalinity: -107

For the second batch, I lowered the amount of lactic acid to 3.5ml, and increased the gypsum to 6.9g and the calcium chloride to 3.2g.  This gives the following profile:

         Calcium: 140.9            Magnesium: 11.8        
         Sodium 8.4                  Sulfate 195.6
         Chloride: 83.1              Bicarbonate: 18.8        
         Total Hardness: 401     Residual Alkalinity: -92

Both mashes should have been in the 5.2-5.4 pH range (I didn't record the predicted pH for the first, but for the second it was 5.4).

On brew day, I took measurements during the first 15 minutes of the mash, and then throughout the rest of the process.  I was still getting the hang of using my pH meter, so the measurements may be a little off, particularly for the first beer, as I was taking a reading too early:
  • Mash pH: at the start of the mash, the first beer settled at around 5.2, while the second settled at 5.4.  By the end of the mash, both beers were in the mid 5.4s.
  • Boil: after 30 minutes of the boil, before the first hop addition, the pH of the first beer was 5.21.  I forgot to take a measurement for the second.
  • Beginning of Fermentation: the pH of the first beer was 5.31, whereas the pH of the second beer was 5.2.
  • Final beer (from bottle): the first beer finished at 4.04, whereas the second beer finished at 3.99
So as you can see, there appears to be some variation in the pH throughout.  I can't make much sense of the numbers, since the first beer started with a lower pH, but ended up with a higher one.  This makes me wonder if I didn't screw up my measurements of the first beer through inexperience with my pH meter.  Either way, both beers were in the right range during the mash.

Of course, these numbers are really besides the point: the real question is how the beers taste, and this is where things went a little awry.  Both are turned out fine in terms of cleanness of flavours, etc.  The Golden Promise really shines through in this recipe, and the bitterness is pleasantly bracing without being too harsh (though more on that below).  I don't detect any of the lactic acid in either. But the second beer attenuated several points further than the first, and this makes it difficult to compare them with each other. Both started at 1.037, but the first attenuated to 1.012, whereas the second went all the way to 1.008.  This means that the beer with more mineral additions is also drier and thinner, and that skews my perception of its flavours.

I'm not sure why one attenuated further than the other.  I tried to keep my process identical across the two brew days, but with no ability to measure pitching rates, I simply eye-balled what seemed to be a reasonable amount of top-cropped yeast, and I suspect I pitched a larger quantity of healthy yeast into the second batch.  This was also the third generation of this particular pitch of yeast.  I noticed as I went on that it became increasingly attenuative across each generation.  This always happens to some extent, but this time I was paying closer attention to the numbers, and I was surprised by how much the attenuation increased in later generations (frankly, it over-attenuated in both Old World's Mantra and Stingo).  Since I haven't seen any other signs of an infection, I'm assuming this is just because I was pitching large quantities of very healthy yeast; but of course, I can't rule out the possibility that somewhere along the line some other organisms got into my pitches and was cropped along with this yeast.

Either way, it makes direct comparison difficult, because the first beer has more body and residual sweetness than the second.  Both are bitter and dry, the second more so than the first; but I don't know how much of that to attribute to the lower F.G., and how much is a result of the differing water profiles.

Second Beer
Here's where it gets interesting.  With the larger part of both batches, I followed my usually practice of bottle-conditioning with table sugar, aiming for around 1.8 volumes of carbonation.  From a bottle, I definitely prefer the first beer.  The very slight residual sweetness provides a nice balance for the bitterness, and gives more expression to the almost cracker-like flavours of the malt.  In contrast, the second beer seems almost too dry, a little harsh, and generally more one-dimensional (though still perfectly enjoyable in itself).

However, I also tried conditioning a small portion of each batch in a Cubitainer, in an attempt to mimic cask-conditioned beer at home.  This wasn't enough of a success to warrant a post yet (I'm going to try again with the Quarter Session bitter I brewed this weekend), but it did mean than I got to try both beers with a lower level of carbonation, around 1.3 volumes.  Here I definitely preferred the second beer: the first seemed a little too sweet, whereas the second was very drinkable.

This really opened my eyes to how much the slightly higher levels of carbonation achieved in bottle-conditioning can affect the flavours of a beer.  I realised that, from a bottle, the residual sweetness of the first beer managed to balance the carbonic bite of the CO2, whereas the second beer was too dry and ended up tasting thin and a little harsh.  From a cubitainer, on the other hand, where the carbonation was lower, the first beer tasted overly sweet, whereas the dryness and bitterness of the second really stood out.  I also significantly preferred both beers from a Cubitainer rather than a bottle; higher levels of carbonation really scrub out a lot of the more subtle flavours in a low-gravity beer like this.  I kind of knew that already, but hadn't seen so clearly the extent to which it was true.

So, while I didn't really learn what I set out to regarding water treatment and mash pH, I did learn something interesting about serving Ordinary Bitters at home.  Hopefully I can get the cubitainers working well, in which case I'll be able to brew something closer to the beers I miss from back in the U.K.  If not, it might be worth mashing higher and under-pitching so that bottle-conditioned beers have more residual sweetness to stand up against the bite of the CO2.

2 comments:

  1. Hi there.
    Im wondering if the attenuation difference was not due to yeast daughter health. (?)
    " I fermented both beers with Wyeast 1469, cropping and pitching from one to the next"
    So,,, you top cropped ? And pitch to the second a few days later?
    The yeast health and pitch rate might have affects on the flavor, not just via attenuation and residual sugars.
    The health of the daughters might be greater in the second than the first?
    What do you think?

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    Replies
    1. Yes, I think that must be right. I was just surprised by the degree to which attenuation had increased by the 5th and 6th generations. It was at 85%+ by the end! Very high for that strain.

      I think in future I need to pay closer attention to my pitching rates when using such fresh and healthy yeast.

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