Monday, 16 June 2014

My first Brew In A Bag (BIAB)

I have done a reasonable number of beer brews using kits, but decided this year that I really wanted to do a brew from scratch. After a bit of research I found that Brew In A Bag (BIAB) is one of the most common ways of brewing so I decided to give it a go.

Since I had the equipment required for brewing kits I just needed to supplement this with a huge pot, a wort chiller, a grain bag, hop bags and a fake bottom for the pot (of which I used an upside down metal colander).

I bought a 50 litre pot with a 0.5cm thick base (I suspect it's a bit thinner) on Trade Me and made a wort chiller (I will write a separate post about that).

I decided to follow the BIAB Pale Ale recipe from Brewers Coop. This consisted of the following key ingredients:

  • 5.3kg Pale malt
  • 300g Pale crystal malt
  • 300g Carapil malt
  • 73g NZ Cascade pellet hops
I purchased all the ingredients from Brewers Coop and they also combined all the malts.

The pot is rather huge on the stove. 

I put 26 litres of water in the pot (with fake bottom inserted) and it took about 30 mins to get up to 68 degrees Celsius. I then turned the heat off and put the grain bag into the pot (with the top of it coming over the sides, poured the malt into it and left it to sit (with some insulation of towels) for 90 mins. The grain bag was unfortunately a bit too small so I couldn't have it over all edges, but it was good enough.

I then turned up the heat to get the brew up to the mashup temperature of 76 degrees Celsius, whilst stirring along the way. This was followed by removing the grain bag from the wort (the name given to boiled up malt) which was quite heavy and made more difficult by the pot being up high on the stove and also wanting to hold it there for as long as possible to get the wort pouring out of it straight back into the pot. I got about another couple of litres by just leaving the bag sitting in another pot (with another fake bottom), but didn't apply pressure since I was worried that over extraction would taint the flavour. The fake bottom was also removed at this point (after a bit of a struggle fishing for it).

I boiled up the wort and 30 mins later added 14g of hops (for bitterness), 30 mins later added another 14g of hops (for flavour) and 15 mins later added 28g of hops (for aroma); given I had acquired 73g I had some left over. I put each of the hops into hop bags so that I could easily remove them at the end of the brew.

After 80 mins of boiling, I added a teaspoon of Irish Moss and inserted the wort chiller so that it could be sterilised for 10 mins before I turned it on. At the same time I turned on the wort chiller I removed the hop bags. The wort chiller took the boiling wort to 22 degrees Celsius in about 15 mins. It is important to cool quickly to get a "cold break" and reduce the risk of infection.

With the help of Jane, we then strained the wort into a cleaned and sterilised fermenter. The wort in the pot was very heavy and it was quite a struggle. I suspect I should look at syphoning for future brews. I then took a hydrometer reading (1.06 OG) and added some rehydrated Safale US-05 yeast. The resulting brew was about 16.5 litres (from the 26 litre starting point. The resting temperature was initially 24 degrees Celsius, but it has already dropped to 23 degrees and should come down overnight (18-20 is where I tend to like it) and hopefully the fermentation will start tomorrow. All going well, I should be bottling in 2-3 weeks.

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