Brew In A Bag
Brew In A Bag

Brew in a bag, you say?! Are you implying that I consume malt liquor from a paper sack? Poppycock! One of the most convenient ways to start brewing All Grain is to use a common practice called BIAB, or Brew In A Bag. This method is an easy way to keep it simple and affordable. It is a minimalist approach to brewing all-grain. It doesn’t matter if you’re brewing clones or your own recipes. Brew in a bag saves on time and money while producing excellent beers.

So what is Brew In a Bag, and how does it work?

With Brew In A Bag, you use a mesh bag as a crude mash tun that goes into your boiling kettle. You steep the grains in the bag for saccharification, then you pull the bag out when it’s time to boil the wort. It all happens in the same kettle.

Tying The Bag
Tying The Bag

There is potential to make a big mess if you aren’t careful. The looks I got from my wife the first time I did it made me question what I was doing. But if done with care, and with a little patience, it can yield some incredible results. One of my best brews was the first time using the BIAB method, and I will do more BIAB brews in the future.

I’ve never brewed all-grain before. Is Brew In A Bag a good way to start?

YES! It doesn’t matter if you’re already brewing extract, or beginning your brewing adventure. Brew In A Bag is a fantastic and easy option to get going in all-grain brewing. The only equipment you need is available at your local shops. Brew in a bag is your easiest start into all grain brewing.

The biggest difference between extract brewing and all-grain is Mashing. Mashing is the process of saccharification (there’s that word again) of grains. Saccharification is the process of breaking down complex carbohydrates into simple sugars. These simple sugars are what get eaten by yeast to produce alcohol. So mashing is steeping grains in hot water to break down carbs and turn them into fermentable sugar. The product of mashing is that sweet sticky substance we know and love as wort. With Brew In A Bag, you are making grain tea with a huge tea bag. The only difference is that this tea later turns into delicious beer.

This sounds great! How do I get started?

The main equipment you need is a basic home brew set-up. The only extra need is a large boiling pot or kettle (I use the words pot and kettle for the same thing: what boils the wort). Ben talks about the basic home brew set-up over here, and that will get you started. Finding a big enough pot shouldn’t be too difficult if you look on eBay, Gumtree or Craigslist. The ideal size for Brew In A Bag is 40 litres, or about 10 gallons. This sounds big, but remember that we need room for grain and room for it to expand in water. It’s also good to have extra room to rinse the grain to release the treats for the yeasties.

Why do I need such a big kettle?

Here’s a quick rundown of grain and water volumes for brewing. When you start brewing all grain, an important point to remember is the amount of water and grain needed to hit your target batch size. as well as reaching your desired flavour profile and alcohol content.

Grain will soak up a fair bit of water that doesn’t get released. Precisely how much water can be a touchy point for some brewers. Every brewer has a somewhat different idea of how much water actually gets soaked up by their grain. According to John Palmer, grain soaks up 2.01 litres per kilogram of grain. According to the popular Promash software used by recipe makers all over, grain soaks up a mere 1.01 litre per kg. Let’s compromise and meet somewhere in the middle at 1.5 litres per kg of grain.

If you’ve got a 5kg grain bill, and aiming for a 19 litre batch, will need 28.5 litres of water.

Wait… What?

My math is not off. There’s another component to this water/grain water volume equation.

The boil.

What happens to water when it’s boiled? It evaporates. So let’s go back to that magic number 28.5. Your 5kg grain bill will soak up 7.5 litres of water. If you wanna hit 19 litres, you need to add 7.5 litres to your target, which gives you 26.5.

Once you’re done mashing, your huge tea bag will have 5kg of grain, and 7.5 litres of water in it. If you start with only 26.5 litres, this only leaves 19 litres of wort in your kettle. Sounds good, but when you bring that to a boil for an hour, it will reduce to a lower volume. For simplicity’s sake, let’s say your boil will evaporate 2 litres. This will bring that precious batch size down to 17 litres. Now I don’t know about you, but I’d be a little unhappy if 2 litres of beer went missing (even though the resulting beer would be stronger).

So before we start mashing, let’s add 2 litres of water to bring the total volume up to 28.5.

This number is only approximate. But if this is your first rodeo it will get you in the ballpark. It’s also good to keep things simple so you aren’t distracted from the process during brew day.

Doing the maths

Here’s that calculation for volumes:

19 litres + (5 kg of grain * 1.5 litres of absorption) + ((2 litres / 60 minutes) * 60 minutes)

And so you start with your target volume, add 1.5 litres per kg of grain for absorption, and add 2 litres of water per hour of boil. Sometimes you might want to boil for 90 minutes, so in that case just change that last 60 to a 90.

A Rolling Boil
A rolling boil. This is not from the Brew In A Bag batch, but the dramatic effect is nice.

Um, you didn’t say I had to do maths. Is this going to suck?

You do need to do some maths. But no, it won’t suck. Think of this as calculating the volume of ingredients and temperature to bake a cake or a loaf of bread. In fact, this is more like baking bread than it is anything else.

I’ll let the cat out of the bag right now. There are more calculations than this for all-grain brewing. But don’t run away if this is your first-ever batch of beer. One of those calculations will estimate how much alcohol is in your beer, and we all want to know THAT. It even uses a simple measuring tool called a hydrometer which takes most of the effort out of it. The other to determine the temperature of your strike water.

Gravity Reading
A pre-boil gravity reading to check efficiency.

In the next part, we’ll go into detail about these calculations and what they’re used for. Furthermore, we’ll touch on what can happen if they’re not quite right. Most importantly, we’ll finish brewing this batch of BIAB beer!

While brewing beer is complex, it doesn’t have to become complicated. Do yourself a favour and remember to relax and be patient, especially with yourself. Ruining your batch can happen, but it’s completely avoidable with proper sanitation. You never know how a batch will go until you’ve sampled the final drop. Edit: Stay patient, let your batch age, and reap the rewards. My best batches have come good at the last pints from the keg…

Have you started your brewing journey? Are you ready to get your hands dirty with all-grain brewing? Or have you’ve smashed out some incredible beers using Brew In A Bag? We’d love to hear about it in the comments!

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