Wednesday, 29 January 2014

"Drop tests".

Two posts in a day?  I must be bored... actually no, I'm simply feeling particularly munificent and think I should show our readers and casual visitors more of what running a craft/micro/cask ale brewery is all about.

Us brewers do some funny things and "drop tests", or as they are correctly called "finings tests", are quite strange looking things appearing to the untrained eye to be a load of bottles lined up which may contain medical samples.  We all do it differently; some use pint milk bottles, some specially bought glass or plastic vessels, some cheapskates use second-hand pop bottles... but whatever you use it fulfills the same purpose in that it allows the brewer to see if the beer he's putting into cask/keg/bottle is going to clear or not.

Personally I hate having to sell clear beer, I'd much rather leave out the fish guts (Isinglass, the final additive in cask beer to make it clear, is shredded sturgeon swim bladders... or "whale jizz" as some brewers have been heard to call it) but the public gets what they stupidly want I suppose.  Call it years of conditioning or whatever, but many people think a beer which isn't crystal clear is defective in some way when it's probably just some flavour-enhancing proteins and hop oils plus a bit of vitamin-rich yeast swimming around in their pint, heaven forfend it should actually taste of something; fining beer strips out a lot of mouthfeel and hop character so by having clear beer you're having worse beer.  Now you know.

Whatever, this picture shows the last week's drop tests all lined up on our "light box".  The sharp eyed amongst you will notice that it's not a light box at all but a girder with a strip light conveniently located behind it (actually it's not that convenient, you have to lean against a wall to get this view...) so you can see the beers on said light box in all their sparkling clarity.  Stripped down to basics, when we transfer a beer to either conditioning tank or cask we take a small sample, add (more or less) the correct amount of finings, shake it vigorously then leave it on the "light box" to await developments.  If everything works correctly - and you can see that these all have worked beautifully - after 15 minutes or so you'll be able to notice clumps forming in the beer; these are yeast cells being drawn to the bits of swim bladder by virtue of electric charge and forming clumps.

The theory is that yeast cells are bloody small and, by themselves, will take ages to settle to the bottom and leave the beer clear, but if they clump together then these clumps will be heavier and will sink faster, resulting in a clear beer much quicker.  There's plenty of books and stuff around if you really care exactly how and why all this happens but it's simpler to believe me that it works.  If it doesn't work, however, then the beer you're putting into cask won't clear in the pub cellar - this is basically an insurance policy as no brewer wants to send out 30 casks of beer not knowing if the beer inside will clear or not (although apparently many don't actually test their beer in this way!)

So there you go, yet another fascinating insight into the bits of brewing that you never see or hear about unless you know a brewer who jabbers on about it incessantly.  In which case I apologise.

Take one twice a day....

1 comment:

  1. Interesting. Would you continue to bother doing a drop test even after the recipe and process have settled down?