Mar 7, 2012

Balance Value and Real Terminal Extract

The beer scene is full of misinformation and even superstition. So many tips are passed on without giving any real reason. Tips become rules and then it's 'DO IT THIS WAY OR YOUR BEER WILL SUCK JUST AS MUCH AS YOU!'

I've had some experience in the coffee scene and found it to be the same. Knowledge can be pretty slow to make its way into the general consciousness. I think it has to do with two factors, the first is that there are huge holes in 'our' understanding. Science is pretty great stuff and there needs to be more of it done to help us understand these delicious beverages. As well as this, the scientific information that is out there can be really dense and without someone to mediate it to people like me whose scientific knowledge is roughly that of a 10 year old, that knowledge is out of reach. 

The second factor is related: the main way information is passed on is by word of mouth (or keyboard). There are so many enthusiasts and comparatively few experts. For the average person to get anywhere in either coffee or home brewing you're really dependent on a couple of things: having someone competent around you to teach you or somehow stumbling on a good book or website that leads you to go further (and that means needing to be pretty discerning and willing to experiment). I know there are some great organisations and websites/blogs offering great information but there's still a long way to go.

I haven't had anyone around me to teach me about brewing. What I have learned has come as I stumbled across things, and looking back, it's amazing that I even learned enough about extract brewing to try it. This means that I've fallen for plenty of brewing myths so far.

This is all a long introduction to what I actually want to write about: the bittering units : gravity units (BU:GU) ratio and a couple of replacement formulas that aim to give a better idea of what your beer will be like, balance value (BV) and real terminal extract (RTE). This isn't really about brewing myths or even misinformation but the other side of that coin, slow trickle of knowledge that makes those possible.

I came across the idea of BV and RTE while I was checking out this recipe (which I'd really like to try). The author mentioned it briefly. The first time I just thought, 'huh, interesting' and didn't do any more with it. I came across it again yesterday and turned up an article on it with formulas and explanations.

The basic idea is that going by the BU:GU ratio and the FG estimate isn't always a very accurate indication of the bitterness/sweetness that the finished beer will have. From the article:
The BU:GU ratio works quite nicely for beers with similar apparent attenuation ratios... Thus, the BU:GU ratio is less useful for beers which are relatively over- or under-attenuated.
The RTE formula aims to give a more accurate account of the residual sweetness of a finished beer by taking the finishing gravity (FG) into account as well as the original gravity (OG).

The formula is: RTE = 0.82 x FG + 0.18 x OG

A beer like the Berliner Weisse I brewed is on the very dry end of things with an average RTE of 9.09. A beer like a Wee Heavy is way out on the sweet extreme with an average RTE of 48.34. 

The BV formula aims to describe the balance between the malt and the hop bitterness. A balanced beer has a value of 1, a beer on the malty side of things like a Southern English Brown Ale has an average BV of 0.73 while a hop heavy beer like an American IPA has an average BV of 1.87. 

The formula is: BV = 0.8 x BU / RTE 

It seems pretty good. It seems like it does a better job of things as far as I can tell. But I do have questions about it. The reasoning behind the factor of 0.8 doesn't completely convince me.
Why the factor of 0.8? With it, the Dortmunder, a beer which belongs to a style which the Beer Judge Certification Program (BJCP) Style Guidelines claim is balanced, has a Balance Value of one.
Now, you can call a beer 'balanced' without intending to mean that it's perfectly balanced. Also, this was based on the 2001 BJCP style guidelines, using the current (2008) version the Dortmunder isn't a perfect 1 anymore, it's 1.08. I guess that might not be a huge deal, the scale still helps give an idea of what to expect even if '1' doesn't turn out to be perfectly balanced. I suppose I just need to try it out for a while and see how it goes.

Regardless of how ideal or not the BV and RTE formulas turn out for me, it's been great to read and think about. I remember what a revelation BU:GU was to me and how it was one of the pieces of information that gave me the ability to start making my own recipes. Hopefully this has pushed my understanding of how to fit a recipe together a bit further.

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