Friday, 14 September 2018

Draught Beer Quality

The second talk at the IBD lectures I recently attended was by David Quain and James Mallett on draught beer quality. It mainly focussed on keg beer and the findings may come as a surprise to those that think any beer in keg (or even key keg) is immune to problems in the trade. For starters it's recommended that kegs should be turned over in five days.




Draught beer is a great thing but quality is not always as it should be.



Draught beer is in long term decline, cask beer is doing best with keg ales doing worst.

Cask Marque and Vianet have produced a beer quality report.






There are a number of factors involved in this decline. It's a tradition or an old charter or something that the 1989 beer orders are given prominence here, but as they broke up the local duopoly where I live and created the guest cask beer market I've a soft sport for them myself.






Beer is a hostile environment for microorganisms but some can still grow.




Germans have a DIN standard for draught beverages.



 The number of microorganisms in a sample can be graded as OK, acceptable but needs a clean or unacceptable.



The speakers carried out some "mystery shopper" type research, surreptitiously pouring draught beer samples they'd bought into sterile universal containers. Some publicans, who let's face it are a shifty bunch themselves, viewed our intrepid investigators actions with deep suspicion.



Pubs on average have three too many fonts.

Microbiology testing is useful but it has limitations. Selective agars are used and bugs can be non-culturable.



So a different approach was adopted...



...and something based on Horace Brown style forcing tests was used.


There's a paper on it in the JIB:


Beer is forced at 30°C for four days and the increase in turbidity from 0-96 hours is measured. The result is scored from A-D (excellent to unacceptable).


As this is a non-selective method it will measure bugs that can spoil beer not bugs that grow on agar plates (I can still see some limitations but it is an elegantly simple solution).


In their trade audit they sampled 237 beers, mainly keg ales and lagers.



Lager quality was higher than ales. Maybe due to higher throughput?



There were differences found between lager brands though. Is it due to throughput or composition of the brand (or brewery hygiene!)?



The more taps on the bar the worse the quality of the beer. It's also worse away from the bar hot spots, so the top tip for beer quality is to order at the obvious places that will get busy not the quiet bit round the corner. Cask Marque accreditation was found to have no effect on keg beer quality.


Spoilage depends on bugs present and the product composition leading to growth and spoilage.







Core best practice is line cleaning, but nozzles and keg couplers also need cleaning. The material the beer line is made from, the temperature, throughput and beer composition will also affect the level of hygiene. The last point about beer composition also reminds me of Horace Brown and his investigations into "the nitrogen question".


Cider, being evil stuff, I mean having a lower pH spoils more slowly and contamination is yeast not bacterial.




Differences were found between brand.

Lagers were tested with spoilage organisms isolated from pubs and investigations into the microbial population in pubs found the spoilage capability remained the same despite variations in throughput.


Line cleaning does work but it is not a total kill. More bugs are found at the top and bottom of the line. The fob detector is another hot spot. Line cleaning only goes in one direction, there is no re-circulation and ideally for cleaning it would circulate in both directions. Weekly line cleaning remains recommended in the UK. Keg couplers can be sanitised.

I was particularly interested to hear that some beer will run back into kegs from the line so kegs can be contaminated once they are broached.


Sparklers are a menace:



They should be properly sanitised at the end of the day.


Soak fob detectors with cleaners and spray kegs and couplers with sanitiser.



Bringing best practice to a pub improved the results to the extent that after training the worst result found was still better than the best result from before training.


Finally:

Glass washing remains poor and this will undermine all efforts at improving beer quality.

There is less support for pubs than before the Beer Orders.

Region brewers go further than most.

Pubs are more focussed on food nowadays.

Regular line cleaning increases profits.

Not much difference was found between free trade and tied pubs.



There were some interesting points raised in the discussion afterwards too. Someone did say that Cask Marque is commercially, not quality, driven, being more concerned with selling accreditation than improving quality. Capitalism, eh?

Third party line cleaning companies can help.

'Spoons clean the lines when a container empties.

Beer lost due to line cleaning is more than offset by an increase in profits due to better quality beer.

Push fits can be non-hygienic (John Guest even came up with "hygienic" fittings but they leak!)

Over complex dispense will increase problems - have the cellar close to the bar!

And it was stated that the scourge of nitro keg ales is ending and they'll be gone in five years.









Wednesday, 12 September 2018

Fascinating facts about filtration

By a cunning bit of arranging I was able to be in Nottingham the same day as some IBD lectures at an inferior Midlands based institution. The first one was about filtration by Rod White, formerly of Molson Coors.


It was based on a survey of large brewers, as it's felt there's still a lack of knowledge about beer filterability. It basically took as a starting point that beta-glucanase was used so obviously it was based on the experiences of industrial brewers as craft brewers would never use exogenous enzymes. Beta-glucanase generally makes filtration one and a half to two times as efficient but some breweries get by fine without using it.






Xylanases usually make a smaller improvement (15-30%) but may help in problems years. Arabinoxylans are present at levels six times greater than beta-glucans but are difficult to measure.



A university based study showed that xylanases worked best to improve filterability.



A lot of variations are found between breweries with brewhouse turbidity ranging from 3-70 EBC. Up to 25% of brewhouse haze is carbohydrate not protein.

Copper finings improve filterability by 25%.

Lowering the loading and reducing raking in the lauter tun can improve performance by 25-50%.



Removing solids (by e.g. adding isinglass to Conditioning Tank) also helps.


Yeast derived material could be a big factor. German brewers measure starch and glycogen and give it an iodine value. Glycogen can be an indication of filtration problems caused by yeast. Are flocculins breaking from the yeast cells and clogging filters?


Beer that spent a week longer sitting on yeast before filtration certainly had poorer filterability. Yeast generation number also affects it.


Ale and lager yeasts also show differences, but dried yeasts were much more filterable. Cultured yeast had much more particles present (trub, etc.).




Brewers can have problems with processing aids. Antifoams in Fermenting Vessel can clog cross flow filter membranes over time, though this is not a problem with kieselguhr filters. Single shot PVPP may also cause problems with cross flow. Tannnic acid can be a great help but can cause problems if added immediately upstream of filtration.




Classic British ale brewing is good for filterability. In a practical, not a moral sense obviously. Mash tuns give good quality wort and as mentioned previously copper and isinglass finings help.

If there are filtration problems it is worth looking at using xylanases rather than just increasing the amount of beta-glucanase used.

Problems can begin in the brewhouse: mill settings and raking will affect filterability. Mash filters are potentially worse.

Roasted grains lead to fine particles that will block 0.5 micron pores. Brown coloured ales are generally fine though.