(Not the JAM/Chris Morris “The Gush”. Search for that on Youtube and watch it if you dare. Just don’t come running to me after you’ve spent four hours swilling your eyes under the tap in a vain effort to un-see it. It’s VERY graphic, you have been warned…)
“…which is the same as maybe two or three squirrels…”
I’m talking about The Gush of beer you very occasionally get when you take the cap off of a bottle of home-brew: One minute it’s all “Ooh lovely, beer for me” and the next it’s *POP*, pretty fountain, beer all over the floor, significant thrashings from the significant other.
But what causes all this unpleasantness? Search the web and you’ll find a wealth of scholarly articles, pontification and half-baked theories.
In reality – and as far as I can work out – there’s only really a couple of plausible reasons:
- Fungal infection
Let’s take a look at each of these in turn:
You must, must, must clean your bottles out. A quick jig about with the bottle under the tap and a squirt of StarSan just won’t cut it I’m afraid.
You need to get a bottle brush into them and scrub about with warm water; or, alternatively get a good soak going with something like VWP (http://www.vwpcleanersteriliser.co.uk/) I’ve used it for years on glass and it’s marvellous. You don’t have to scrub, just soak for as long as you can bear and then rinse well.
Dirty bottles (even minute specks of accumulated crap) will harbour all manner of amusing wild yeasts and bacteria – all of which are capable of dealing with any residual sugars that brewers yeast can’t…making for dangerous levels of carbonation. Anyone for bottle bombs?
Too much priming sugar can also dangerously over-pressurize your bottles. There’s two astonishingly easy ways to make your very own beer fountain in a bottle:
Double-dosing loose-priming sugar is my favourite way of doing it: that’s where I get interrupted when I’m adding my 1/3rd of a teaspoon of table sugar to each sanitized bottle and end up sticking multiple loads into some.
Get into the habit of priming a bottle and then loosely placing a sanitized cap on top – to show that you’ve primed it; then when you’ve got all the bottles loose-capped you can start racking into them.
The over way of doing it is when you add priming sugar to the bottling bucket. It’s just so easy to dump the priming solution in and then forget to stir it…
If you don’t stir, that sugary mixture will delight in making its way to the bottom of the bucket where it’ll squat about until it jumps into the last few bottles being filled – all of which will then have waaay more priming solution in them than they should.
With the quality of the malts that we get from people like Rob and Greg ( www.themaltmiller.co.uk and www.brewuk.co.uk respectively) you’re unlikely to have grains that have been infected with Fusarium Head Blight.
Fusarium is a fungus that attacks the growing barley or wheat grains and lays dormant when it’s harvested only to get going again during the steeping phase of malting.
When the malt is kilned the Fusarium fungus itself is destroyed, but it does leave some of its unpleasant byproducts behind, the most important to us is deoxynivalenol – a mycotoxin that is tough enough to easily survive the boiling of the wort – and persists in the finished beer as lots of tiny bits and pieces of protein.
These millions of bits and pieces of protein provide millions of nucleation sites for the CO2 in the beer.
Nucleation sites are where CO2 is able to come out of solution rapidly and cause bubbles – lots of nucleation sites means lots bubbles and lots of bubbles means lots of foaming.
As mentioned, Fusarium is rare but could provide a handy and knowledgeable-sounding excuse for that bottle of beer you gave to someone that’s now all over their ceiling and floor!
You may be wondering what prompted all of this musing on The Gush…well, back at the end of Summer this year I had a batch of porter and a small run of Golden Ale that went off like rockets when opened.
I put both of those down to bad hygiene as I was in a rush when I bottled.
I now take much more care when bottling…after all, it’s the end product that people see – and you want that to be perfect.
Sources: My brain and http://morebeer.com/brewingtechniques/bmg/gudmestad.html