Clarity Problems

This is not a marketing blog. That’s because we don’t have anything to sell (did you hear that, Mr Duty Man??). And it means that this blog is not all about “we made this lovely beer” and “we made that lovely beer”. Sometimes things go wrong. Happy to admit it – that’s how you learn.

The previous blog post is a case in point – we’re currently drinking pretty much flat lager.

So here goes with another. What the hell happened to our ability to make clear beer??

This problem has afflicted the last couple of brews: East Kent Goldings Single Hop and Liberty Lightning.

The funny thing is that the beer seems fairly clear when it is racked out of the fermenter. Then it sits in the keg to mature for 4-6 weeks (a period of time soon to be designated a “Burrows”). When served we end up with the haziest beer you’ve ever seen (see the photo below). It’s a bit embarrassing giving it to friends to be honest.

I can only think of a couple of possible reasons:

1. Dry hopping. Maybe adding dry hops after fermentation has somehow affected the clarity.
2. Yeast activity during conditioning. Maybe the yeast’s secondary fermentation is so vigorous (especially given the warmer days of “summer”) that it’s kicking up a load of yeast into suspension and not settling out.

Certainly the vigorous secondary fermentation of the Liberty Lightning points towards the latter possibility. But I’m really not sure. Here’s hoping the Citra American Pale doesn't suffer the same fate.

Making lager fizzy

It’s funny how sometimes what would on the face of it appear a fairly simple thing turns out to be much much more complicated…

If you are our regular reader, you will remember that way back in April we made a Czech-style lager, named Bohemian Wrenbury. This has been lagering (cold storage) for many weeks, but now summer is here (ho ho!) we want to drink it. But obviously being lager it needs to be fizzy.

As everyone knows, the bubbles in fizzy drinks are carbon dioxide. How do you make beer fizzy? Well there are two ways: first is to provoke a secondary fermentation. Fermentation gives off carbon dioxide, so if you keep the beer sealed it will dissolve in the beer. This is how we carbonate our ales. The second way is force carbonation, i.e. seal the beer and use bottled carbon dioxide.

As I said, for our ales we use a secondary fermentation. So why not just do this for the lager? Well, mainly because of the lack of yeast. After many weeks of lagering, I think most of the yeast will have dropped out of the beer. Plus the lager is in the fridge, so any secondary fermentation would take a long time. And finally, it’s a bit uncontrollable. You add sugar to power the secondary fermentation… if it didn’t ferment we’d end up with somewhat sweet lager.

So we decided to try force carbonation. First problem: how do you know what pressure you have in your keg? After much research, I bought a keg pressure gauge on eBay:

After a bit of drilling, tightening and testing it was fitted and seems to work OK.

Next problem – how much pressure do you need? The first thing to say is that the amount of carbonation in beer is measured in “volumes”. That is, carbonation to one “volume” means you have dissolved the same volume of carbon dioxide in your beer as you have beer. Two “volumes” means twice the volume of carbon dioxide has been dissolved as you have beer.

Generally lagers are served at between 2 and 2.5 volumes. So far so good. Now the amount of carbon dioxide you can dissolve depends on the pressure of the gas above the beer and also the temperature. A quick look on Google reveals some handy charts for the pressure (in PSI) required to attain a certain level of carbonation versus temperature. Yes, temperature plays a part: the colder the beer the more gas you can dissolve in it. This sounds counter-intuitive, but it’s right. For dissolving salt in water, you need it to be warmer to get more to dissolve. Not so for dissolving a gas – for that you can dissolve more gas at lower temperatures, because a higher temperature means more energy in the liquid, which can drive the gas out of solution and into the space above.

All fine, except that you need quite a lot of pressure, even at about 5C, to dissolve 2.5 volumes or carbon dioxide. More pressure, unfortunately, than the King Keg is supposed to tolerate (10-12 PSI max). Bugger. But given that I’d got this far I didn’t see that there was much else I could do but go for it, and see how much carbon dioxide I could get to dissolve. So far it turns out that the answer is “not enough”. When served, the lager comes out at quite a gush (because of the pressure above), but it doesn’t hold any bubbles. Just the very slightest hint of carbonation, like mostly flat mineral water. Arse.

On the plus side, the beer itself tastes and smells wonderful – just like Budvar. And it’s nice and clear.

So what was the “right” solution? To invest in a “cornelius keg”, which can hold much much more pressure. But I don’t think one would fit in my fridge. So this is going to take a lot more thought and experimentation for future lagers.

New boiler

On Tuesday we made the second of our Belgian beers – a Belgian Dubbel. The brewday was enhanced by the arrival of a shiny new boiler for my birthday (thank you Gill!).

“Hang on!!”, I hear you say, “you’ve got a lovely vintage Burco boiler, what do you want to replace that for?”

A couple of reasons really. Firstly, the new boiler is slightly bigger (29 litres versus 22 litres), which means we can boil the whole batch (previously we’ve always boiled a little under the full volume, then topped up with a bit of water at the end). Bigger also means the liquid isn’t anywhere as near to the top. Much safer!

The second reason is speed. We have been able to shave some time off our brewday by using both boilers. The old Burco is now just a Hot Liquor Tank (HLT). Previously it had to do both jobs, which meant that we had to collect the runnings from our mash tun somewhere else until we had completely finished sparging and no longer needed hot water. Then we transferred it all across to the Burco to start boiling it. Of course the wort was cooling down during all this time, so with the new boiler we can start heating the wort much sooner, saving time.

Oh, and I’ve just thought of a third reason. The new boiler has a nice filter at the bottom, which holds back hops and trub (precipitated proteins) as we are running off. I suppose in theory that should mean clearer beer, although there is some debate about that in brewing circles.