Tuesday, 22 May 2018

May is the month of mild

May is the month of mild,
Month we all love so well;
Mild is god's own beer,
Gladly it's praise we tell

I was starting to panic about this year's Beery Month of Obligation. Well over half way through it I'd not seen a drop of mild and I didn't know where to look. Fortunately for me a tweet from Lars Garshol helped me track down mild to the Royal Oak in Borough. So with a slight detour on the way to a home brew competition success, and spiritual well being, were mine.

In fact this year I'm feeling positively virtuous as they had both light and dark mild on.

The light wasn't that light mind.

But the dark was properly dark and the one I preferred. If I saw it more often I'd drink a lot more of it. Sadly though as Harvey's are supporters of the Small Brewer Duty Reform Coalition there's no chance I'll be seeing it in my local.

Friday, 18 May 2018

Living the dream: a visit to Mogden sewage treatment works

I was accosted by a train nutter on Monday. My quiet reading on the finer points of fermentation was interrupted by someone keen to tell me about the gaps in railway tracks. Not something I was desperate to learn more about, but it's not like I had a choice. Fortunately I soon changed at Clapham Junction. Whilst my new friend was heading home I was spending my free time visiting a sewage works. Which did give me a little twinge of doubt about which of us was the sane one.

Mogden sewage treatment works holds a special place in the hearts, or possibly wallets, of brewers as its name is immortalised in the Mogden formula, the way in which effluent costs are calculated.

It was built on a farm in the 1930s to replace 28 smaller sewage works. It now deals with over two million peoples worth of sewage. It was originally surrounded by fields but now is surrounded by housing so controlling the smell and mosquitoes is a key concern!

As is often the case I can't remember the name of the speaker but I think it's fair to say he was a big cheese in big jobs. We got told all about the sewage treatment process and of course about the famous formula:

Here it is

Bask in its glory
The cost is calculated on the conveyancing of the effluent, the volume, the biological treatment cost and the amount of suspended solids. To reduce the effluent costs reduce the volume, Chemical Oxygen Demand, and suspended solids.

The situation is complicated slightly by the fact that as different sewage works deal with different issues there are in fact many Mogden formulas:

But I feel confident that being at Mogden sewage works we were seeing the original and best.

Sewage is treated in several stages:

First it is screened to remove solids like wet wipes, traffic cones and dead goldfish. This forms "rag" which is taken off in lorries.

Grit is then removed in a process that sounded a bit like how a brewery whirlpool operates.

Primary treatment next takes place in a settling tank.

These have a sloping floor on which the sludge settles from which it can be scraped off and pumped away for further treatment, whilst the liquid goes to aeration treatment.

In final settling tanks live and dead microbes settle out as more sludge which is sent for treatment and water which can be sent to the river.

The sludge is thickened with a polymer so there's less to pump and it goes to anaerobic digesters linked to Combined Heat and Power generators which make a Gigawatt a week.

I'll have to check with Alanis Morissette but it may well have been ironic
that one of the khazis at the sewage works was out of order. 
After digestion the sludge is de-watered in centrifuges and goes to farmers.

And here's a heron
After the tour it was on to the networking.

The Pride was drinking well

Thursday, 26 April 2018

Rejoice at the CAMRA vote!

I've found the recent outbreak of people spouting nonsense about CAMRA surprisingly disturbing.  But I have to accept that everyone can get it wrong and that does include me.

I may not have got it as wrong as half the twerps on twitter, but I did miss what is surely the most important result from CAMRA's AGM. No, not the acceptance of keg beer. Or the acceptance of extraneous CO2. Or even that the failed motion that so many people have got het up about was really about pubs.

No, surely the most important decision was that both the anti-'Spoons vouchers candidates were rejected. That bloke from Tiny Rebel who was far too full of himself and the young fogey who runs a pub were both anti-'Spoons vouchers and both were soundly defeated. So let us here no more of this anti-'Spoons voucher nonsense. The people have spoken.

Wednesday, 25 April 2018

Dry hopping and a visit to Lupofresh

Dry hopping, the traditional British technique that was invented in America in 2007, is all the rage now. So it was with interest that I went to Lupofresh to hear a lecture from Russell Falconer of Hopsteiner on it. Shame I didn't get to the IBD Asia Pacific conference as there were six lectures son it there.

Dry hopping, adding hops to beer after (or even during) fermentation, is the best way of getting hop aroma into beer.

Where hops are added to the beer has a strong influence on how they affect the flavour. With dry hopping there's heat so the essential oils aren't driven off so remain in the beer. Rates have risen from a modest 20g/hl up to 1000!

The oil content of hops varies from year to year by up to a factor of two and doesn't show much correlation with alpha acid content.

Various methods are made to add different types of hops at different stages.

Whole hops, type 100 pellets (hop plugs), hop pellets, in a bag or loose.

Adding dry hops loose gives more flavour than in a bag.

More oil is extracted over time but it can also add negative characteristics (vegetal flavours)

Separate dissolving tanks which the beer is recirculated through are becoming more common now. Dissolving hop pellets warm gives better results for the first 24-48 hours but after that point the results are the same as if the dissolving beer was cold. Some new systems can get the flavour out in four hours.

It can be used in conjunction with the Iso-Mix system (which re-circulates beer through a submerged jet head) or GEA hopstar which has a perforated up pipe.

It's possible to drop pellets out a cyclindro-conical fermenting vessel and then crop yeast later. Dry hopping will cause beer losses as they can swell up to size times the size they are when added.

Hopsteiner have developed a "beer cleaner" with a 250μl sieve for separating beer from hop debris.

Losses can be reduced by using lupulin powder (made in a similar manner to Type 45 pellets so luplin glands are concentrated and "leaf" matter reduced) or you could add hop oils.

Despite the lack of boiling (so no isomerisation of alpha acids) dry hopping will still increase bitterness.

There are changes during fermentation due to adsorption, interaction with products of fermentation and biotransformation.

And just when I'd decided the only important thing about fermenter geometry was height and the associated difference in hydrostatic pressure it turns out there's more to it. Greater the surface area at the top of the tank the greater the amount of volatiles lost.

In large tanks there will be different concentration of hop flavour volatiles in different parts of the tank so mixing ins better.

Filtration will remove flavour compounds, but some more than others. Myrcene (grassy/estery) is mostly removed by fruity notes tend to go through the filter.

Storage trials of beer stored cold and warm (c/w) showed marked reduction of most hop oils

Mixing and amount of contact are more important when dry hopping than temperature (though yeast interactions will be affected by temperature).

In the discussion that followed there were a few more juicy titbits. Fullers pick up 6 IBU (by analysis) cold dry hopping, which will come from oxidised products not isomerisation.

There is an optimum length of time for dry hopping so dry hopping in tank gives a more stable product.

Dry hopping increases the beer pH so there can be an increase of 2-3 IBUs due to this.

Sadly the speaker could shed no further light on the diaststic effect of dry hops but Horace Brown mentioned it in his wonderful reminiscences and more than a century after Brown's work there's a podcast about it from the MBAA here.

And then we had a tour of Lupofresh/Morris Hanbury.

It wasn't quite like when I went round a hop processing plant in Germany, which no doubt reflects on the relative successes of the British and German hop industries.

Type 90 pellets are made by hops going to the bale breaker, they may then be subject to further drying before going to a hammer mill before mixing, cooling, pelleting and packaging.

Anyone else remember Reanimator?

Proper science coming up:

Morris Hanbuy make Type 90 and Type 100 pellets, Isomerised Kettle Extract, Iso-alpha extra and reduced Tetra extract with the hydrogenation carried out in house using a novel process.