Diary of a Brewer: Trial Week Part 2

Link to Diary of a Brewer: Trial Week Part 1

So the shift rota over the last few days has allowed me to catch up on some sleep and has even been sparse enough to allow me to write another entry! I wrote 'Trial Week part 1' while sitting in The Elizabethan pub after working the morning shift on Wednesday knowing that I did not have to be at work until 22:00 on Thursday night. Naturally I was exhausted and should have finished my writing and gone to bed. But this would have been the sensible, and far less fun thing to do.

The bartender, a very nice man named Raymond, brought me a free pint of Punk IPA as a 'welcome to Fraserburgh and welcome to BrewDog' just as I was finishing the last paragraph of my previous entry. And after I finished writing I joined him and few of the locals at the bar to enjoy said pint. They were a great group of people who were very welcoming and enthusiastic about my new job prospect, so much so that I didn't pay for another drink. When 1:00 in the morning came round, and we were filing out the door of the pub, Raymond asked me if I wanted another drink. Apparently we had all gotten up, and made it out the door of the pub, because this was the only way to convince one of the locals (who was quite drunk) that it was time to leave. Once he was out of sight we all piled back into the pub and resumed our places at the bar. Raymond had given me the wireless code for the bar earlier in the evening so I pulled my laptop out and put on a selection of songs that those sitting at the bar requested. The drinks kept flowing and before we knew it we were all stumbling out of the bar at 4:30 in the morning. A fine welcome to Fraserburgh!

Needless to say, because of my antics the night before (including god knows how many pints of Punk IPA) I slept for the majority of Thursday before starting the night shift at 22:00. I was working with Oscar, one of the assistant brewers, and Stewart. When we arrived the afternoon shift had just mashed in on a batch of Paradox. Paradox is a 15% imperial stout that is aged in Scottish Islay whiskey casks. Because of the high alcohol content of this beer compared to standard ABV beers it requires 1350kg of malt to produce 30hl of wort with an original gravity of 1090. This however is not high enough and so requires the addition of ~150kg of malt extract to raise the gravity to 1112.

Because of the high grain bill and relatively low yield of the wort the mash is done with a liquor to malt ratio bordering on 2ml/g. When the ratio gets this low care must be taken to sparge and transfer the wort VERY slowly into the copper to ensure the very high original gravity target. As mentioned previously we normally transfer from the mash tun to the copper in 3 hours. This particular batch of paradox took nearly 5 hours to transfer. While the transferring was happening I was busy with another round of tank actions as well as PG checks, or as they are less affectionately known 'waste of beer checks'. These checks involve drawing 2 litre sample of beer from any FV filled with actively fermenting beer. The sample must then be de-gassed by pouring it back and forth between two vessels for several minutes. The programmed temperature of the FV is noted as well as its actual temperature. We then take a hydrometer reading of the de-gassed beer and manually take its temperature to adjust the reading according to a table of temperature and gravity specific adjustments. These values are documented at 3 hour intervals for the duration of the fermentation. This way any anomalies (in gravity or temp.) can be found quickly, and any stuck fermentations can be discovered before they cause too many problems.

I feel I should speak more about why the transfer of the paradox mash took so long and how we know we need to run a transfer this slowly. When we move the wort it flows out a pipe connected to the bottom of the mash tun located at the centre of the false bottom. This pipe then feeds into the bottom of a 35 litre pail (underback) that sits between the tun and the copper; another pipe feeds out the other side of the bottom of this underback and is connected to a pump that will move the wort into the copper. The first step in transferring the wort is to close the valve that leads to the pump while opening the valve that drains the copper so that the underback begins to fill. Depending on the size of the desired batch we are aiming for the underback to fill with 35 litre of wort in 100-120 seconds. When we have adjusted the valve on the bottom of the mash tun so the underback is filling in this specified time we know the hourly flow rate out of the mash tun. We must then open the valve leading to the pump so that we balance the incoming and outgoing flows from the underback. Every 45 minutes during the transfer we must document the flow rate, the gravity reading and pH of the wort in the underback, and the volume of the copper thus far. We should see a steady rise in successive values of gravity followed by a steady decline. Gravities that are too low tell us we should slow the transfer, and gravities that are too high mean we should increase it by adjusting the flow rate from the mash tun into the underback. Hence the Paradox took nearly 5 hours because our gravity readings from the underback were consistently below our target and the flow rate was reduced several times in an effort to raise the gravity.

After the transfer was complete I shovelled out the mash tun for the third time this week (an also found out from Stewart that the temp. in the mash tun is regularly 80C+). Once the grains were shovelled out I housed down the inside of the tun and prepared it for the next batch of malt. Surprisingly when I had finished cleaning the tun the shift was over. It was already 6:00 in the morning and the first shift was arriving. It was a very busy and informative night but we had only managed to complete the mash and transfer, and we were just beginning the boil after 8 hours of work.

I suppose there is a reason that Paradox costs £6.50 a bottle.

Link to Diary of a Brewer: Trial Week Part 3