Brew In A Bag: A Step by Step Guide

Brew In A Bag Equipment 

If you're already up and running with an all-grain or extract setup, you'll need very little to get going with Brew In A Bag (BIAB). Mainly... well... the bag.

As has been the case with quite a few other items, I was lucky enough to have MacLeod 9 send me a proper LD Carlson nylon bag from the States, but any light weave, strong fabric would work just fine. Emphasis on strong. You'll be lifting up to 10-15kg of wet and unruly grains, so make sure the bag can handle it.

The other vital piece of equipment most likely came with your brewpot if you bought it here in Korea: a false bottom. The grain bag will be standing in the brew pot for quite a while with BIAB, so there's a very real risk of burning the bag and the precious grains within it if it's left alone on the bottom. By tossing in the false bottom the grains are kept from the danger zone and will allow the water to circulate more freely. If you don't have a pot specific false bottom a metal colander flipped upside down will do the trick.

 

BIAB Brew Day

1. Prepare Water

Unlike extract or all-grain brewing, the water you start with will be the water you use for the day. You'll want around 40% more water than your target volume to make up for what will be lost to evaporation during the boil, soaked into the grains, and left in the pot as trub at the end. The amount of water you'll use can (and most likely will) vary depending on your setup, so be sure to take some notes.

I use 20 liters of water to get roughly 14 liters of finished product each brew. Unfortunately, I've had to tweak things slightly to use 20 liters since I have the misfortune of a brewpot that's a wee bit too small. I have 18 liters of water in my main brew pot and 2 liters in a kitchen pot that will be used as sparge water later on. This is not the traditional way to BIAB, but it's any easy out in a pinch for space.

Once the water in your main brew pot is ready to go, get it slihgtly hotter than your target mash temperature. This will help make up for the cooling effect of adding the room temperature grains.

2. Add Grains

When your strike water's ready, slowly submerge the grains into the pot. This is the moment of truth if you're unsure about the amount of water you put in, so be sure to take your time. The last thing you want is to find out you have too much near-boiling strike water as it pours all over your foot.

Once you're sure everything fits nice and snugly, stir the grains until they're submerged and wet.

On a side note, here's the first big no-no of my setup: the bag doesn't fit around the brewpot. It's still quite doable to brew this way, but it's amazingly annoying compared to having a bag that fits. Keep this in mind when purchasing (or making) your bag.

3. Mash

With a target mash temp of 68°C and 60 minutes to keep it in that range, you'll have to get a little creative. One of the easiest solutions is to put the brewpot lid on and grab an old towel. Wrap the towel around the pot to try and keep the heat as close to your target temp as possible.

Throughout this process you'll also want to stir the grains occasionally to ensure the water temperature is the same throughout the brewpot. Otherwise the thermometer readings will be thrown off based on where you place it in the pot. Stirring will also help prevent the proverbial danger zone at the bottom of the pot mentioned earlier.

If at any point the temperature cools too much, don't be afraid to remove the towel and turn the stove back on. Try to keep the mash as close to your target temp as possible by any means necessary.

4. Drain

After the mash time has elapsed, carefully lift your bag from the pot and let it drain into the wort. This step provides another great reminder about buying a seafood pot here in Korea: pot specific strainers. Most of these giant crab-killin pots will have a specifically sized strainer that fits perfectly on top and will cost all of ￦4,000. Buy this every time. The other option is to hold the soaking wet grains while they drain into the brewpot... it ain't fun.

While the grains are draining, it's an optimal time to get the 2 liters of sparge water up to temperature in the standard sized kitchen pot. Again, this is not part of the traditional BIAB process, but I've found it's a great way to utilize the grains to their fullest.

A number of your "extra" items can make this step a breeze. The first thing you'll want to do is grab your bottling bucket (all good and sanitized and whatnot) and place the false bottom from the brewpot into the bottom of the bucket. By doing this you'll allow the grain bag to continue to drain while pouring water over the top. A lot of times folks will simply leave the bag in the bottom of the bucket to drain, and that will work... but not as well.

Once your 2 liters of kitchen pot water is up to temperature, just pour it over the grains in the bottling bucket and let it drain for 15-20 minutes. Unless you're working with a ridiculously strong burner, you'll have at least that much time to add your new sparge water back into the brewpot before the wort gets up to a boil.

5. Boil

If you've done an all-grain or extract batch before, then these steps are nothing new to you. You're on easy street. Should you be completely new to brewing, it's still pretty close to easy street.

Crank the heat on your burner to bring your wort to a gentle, rolling boil. Since you're heating roughly 16 liters of water this will take a little while, but it'll get there. Once the wort is boiling follow your recipe's hop addition schedule for bittering and flavoring hops.

6. Chill the Wort

Once the boil is finished you'll want to get your wort temperature down to 21-26°C. 26°C is about as high as you can go without running the risk of killing the yeast you'll be adding shortly. There are a number of ways to get your wort cooled down, with a wort chiller being one of the most efficient. Unfortunately, I've never had a sink that would allow attachments, so I've always used the ice method, which works just fine. Also, a wort chiller can take up quite a bit of precious space in the tiny apartment world of Korea.

This is a step where the ￦5,000 tub is worth its weight in gold. I make quite a bit of ice at home the night before my brew day and throw it all into the bottom of this tub and it works quite quickly to cool the wort. Stir the water occasionally to ensure the pot is being cooled equally on all sides and add more ice if necessary. If there's anything I've learned for this step it's that you can never have too much ice. Fill your entire freezer the night before. You won't regret it.

7. Pitch the Yeast

Once the beer is in the 21-26°C temperature range, transfer it to your fermenter. Though it's a good idea to use your auto-siphon to transfer from the brewpot to the fermenter, I just pour straight from the bucket through a strainer. You'll run the risk of more trub (what will be left in the bottom of the fermenter at the end of fermentation), but I've never noticed a drastic enough difference to justify the amount of time spent using the auto-siphon.

After your beer is in the fermenter rinse your strainer real quick and pour the beer right back into the brewpot. Then back into the fermenter (always through the strainer). By pouring the beer several times between the fermenter and the brewpot you'll help aerate the beer and create a better environment for your yeast to properly ferment the beer.

When the transferring and re-transferring is all done, record your Original Gravity. Then add your yeast. For the batch pictured I had a dry yeast packet of Safale S-04 (English Ale yeast) which I added straight to the fermenter and stirred in. A common practice is to rehydrate the yeast... but I don't. There are a lot of good reasons to do this, but I've never had any issues with the results of simply throwing the dry yeast into the fermenter and stirring. If you can get it easily enough, I recommend liquid yeast which ends the debate of rehydration altogether.

8. Ferment

Pop the lid on your fermenter and place it in a cool and dark place that has a fairly constant temperature of 15-21°C. If you don't have such a place, wrap the towel you used during the mash around the fermenter to prevent light from getting in. In roughly 12 to 24 hours the beer will be actively fermenting, which is pretty cool to watch if you have a clear fermenter. In opaque fermenters you should notice your airlock bubbling away.

Total fermentation time can vary, but the average is 8-14 days. I almost always give mine 14 days, but have occasionally left it for 21-25 days with no issues. You'll know fermentation is finished when the airlock bubbles less than once every 60 seconds. The beer will also be quite cleared up at this point, with the bottom quarter or third of the fermenter still a bit cloudy. When the fermentation is completed, record your Final Gravity and get ready for bottling.

Brew In A Bag In Review

1. Prepare Water
2. Add Grains
3. Mash
4. Drain
5. Boil
6. Chill the Wort
7. Pitch the Yeast
8. Ferment

If you have any questions, comments, or concerns, please comment below.