...go out tonight and drink the grog of my local regional brewer and drink 5 pints of what is branded the same bitter, and all will taste different.
I've been trying to imagine some possible scenarios where this might actually happen. i.e. not just one of those things that we all nod at, without thinking "hang on, that's b*ll*cks".
- 1.1 Five pints in five pubs of varying quality
- 1.2 "he's just changing the 'barrel'"
- 1.3 glassware issues
- 2.1 Drift of taste - saturation / habituation effects
- 2.2 Other taste effects. Interference by peanuts / crisps / last drink /etc
I'm not going to expand all these points now. That would be really dull.
OK, so. Your Real Ale is known to be sensitive to issues in the first group. It can be kept or served badly, or well; at the wrong temperature; in dirty or inappropriate glasses. There may be some detectable taste change during the "shelf life", we're talking about live products, which will have some microbiological activity continuing (you'd hope mainly yeast). Equally, these types of beverage do have a serving life over which there will be some taste change. In the second group - since taste is an issue, then subjective taste changes will be noticable.
On the other hand, for other beverages served with high levels of dissolved gas, at low temperatures, in near-sterile conditions and protected from oxygen, flavour (as such), where detectable, will tend to be more stable. Since taste is less of an issue - it's been reduced to at or below threshold by fizzyness and temperature - the process managers / brewers can be more confident that issues of the second kind will be less troublesome.
That's the post-packaging variation pretty much deal with.
Looking at the big variables in the brewery - we can tolerate some variation, as long as it's less than most of our customers will detect.
For instance, bitterness (measured in units called European (or International) Bitterness Units i.e. EBU or IBU - pretty much the same) isn't well resolved by most tasters. You'd be very lucky to find an untrained taster who can spot the difference between 35 and 40 IBU (other things being equal). So in the brewery, if you're aiming at 40 IBU you'll need to be confident that you're between 35 and 45. i.e. +/- 10% is probably good enough. (I'm sure I've read that a lot of people top out around 70 IBU, so there'll be little perceived difference between 80 & 90 IBU. i.e. big beers are easy.)
Problem is, hops (a) change with age and (b) vary from batch to batch. So we (a) don't buy more than we need and we store them cold (we freeze open packs), and (b) recalculate how much we'll need based on the analysis of each batch. Not everyone does this - but since the inter-batch variation can be 20% - This might mean that your beer, meant to be 40 IBU, comes out almost 50 - quite a few people will detect this (the brewer should be one of them).
Gravity and strength depend (mostly) on how much stuff we put in. This will be mainly malt (and water - thanks Dave). Malt comes in handy 25kg sacks (for the small brewer that is - the big boys get it by the truck or railcar). That's easy - you need 125kg of malt in your recipe? Take 5 sacks and you're sorted. Well, not always. And this is a bigger problem the smaller your mash tun is (that's statistics for you). The maltsters seem to do a minimum fill - pretty much. Occasionally those 5 sacks could easily mass 135kg or (much more rarely) only 120kg. So before we start congratulating ourselves on the cracking Mash Efficiency we got this time, let's check-weigh those sacks-o-malt. Otherwise that beer's going to be almost 8% stronger than we meant it to be, unless we liquor it back (i.e. dilute it) in which case we've just knocked the bitterness (and colour and everything) back haven't we?
As has been pointed out before, the bigger brewers have the lab facilities and the big blending tanks that support working to real tight specifications. But there's no reason why with reasonable care a small brewer can't work to perfectly acceptable limits.
See, what I'm saying here is that the Real Ale is susceptible to post packaging mishandling. This is an simple one for the drinker - don't go to crap boozers. Or if you do - drink cold fizzy stuff that's harder to f-up. And small brewers need to weigh stuff properly, clean like crazy and do some simple arithmetic.
Always remembering that the important thing is that it should taste good. Consistently good.
Easy really. Touch wood. Fingers crossed.