Home Brew in a Bag (BIAB): The Definitive Guide

When it comes to homebrewing beer, Brew-in-a-Bag (BIAB) can be one of the easiest and most efficient ways to homebrew beer if you’ve never done it before. BIAB bags take the guesswork out of adding your grains and extracts and instead let you focus on other technical aspects of the brew such as temperature and duration.

Brew in a Bag (BIAB) brewing is a form of all-grains home brewing that can be completed in a single kettle. This makes it an easy and efficient form of home brewing beer, especially for beginners. The brewing bag is steeped in the brewing kettle in a similar way to steeping a tea bag before being removed to boil the wort without it. 

If you’re new to home brewing your own beer, BIAB bags can be one of the easiest ways to dip your toes into the hobby.

Keep reading to learn more about home brewing in a bag and the ways you can get the best results doing it.

What is Brew in a Bag (BIAB)?

BIAB brewing is one of the easiest ways to get into homebrewing your own beer if you’ve never done it before.

There are BIAB setups for all different kinds of beer.

No matter what type of beer you prefer to brew and drink, you can probably find a BIAB bag that will give you the type of beer result that you want. 

While there are many different kinds of homebrewing setups—some more complicated than others—you can’t get much simpler than a BIAB setup.

To homebrew beer with a BIAB, all you have to do is place your brewing bag of grains, additives, and extracts into the brewing kettle, boil them for a pre-specified amount of time (depending on the bag size and beer type), and then removing the bag to continue to boil the wort.

Here are some characteristics of a BIAB setup:

• All-grain brewing: All-grain brewing involves using crushed malts mixed into the grain bag, which prevents the need to add malts separately and measure them in.
• Single-vessel brewing: Unlike other types of home brewing, which often involve racking and siphoning the brew into multiple vessels, BIAB bags involve using a single brewing kettle.
• No-sparge brewing: Unlike other brewing methods, which involve rinsing your brewing grains multiple times to remove excess proteins that can remove excess sugars from the brew in order to change the flavor profile of the beer and the amount of alcohol in the final result.

Unlike more complicated forms of home brewing, where the brewer can accidentally ruin an entire batch of beer just by miscalculating during the multiple steps involved, BIAB brewing cuts out a lot of the guesswork and makes the entire process much easier.

What Are the Differences Between BIAB and Normal Brewing?

BIAB brewing does share some steps and characteristics with normal brewing procedures, but there are also some major differences, too.

Here are the main ways in which BIAB brewing differs from other forms of brewing:

• The use of the single vessel for all brewing activities. Most homebrews involve brewing the beer in multiple vessels, but BIAB is one of the few setups with a minimum of brewing equipment. This is one of the reasons why it is a preferred brew style for home brewers who are still getting their feet under them in the hobby.
• The lack of rinsing/sparging/lautering activities. Sparging and recirculating your mash is one of the more tedious and time-intensive steps in conducting a brew, and taking these steps out of the process can leave you with a good brewing result with only a fraction of the work involved.
• BIAB brewing involves following a preset recipe. The grains for BIAB setups usually come pre-calculated with the amount of grains, malt extracts, and other ingredients necessary to make a batch of a specific beer. For example, you may get a BIAB grain set for an all-American lager, or a stout beer. This takes much of the calculations and experimentation out of the brewing process, allowing for new brewers to focus on the process of brewing rather than the recipe.

Many steps in a BIAB brew are very similar to the ones you would undergo with a traditional home brew operation.

They are just condensed for the convenience of the brewer so that you can make a batch of beer with less equipment, with less experience, and in a smaller space.

Advantages of BIAB for Home Brewing Beer

BIAB brewing offers several benefits over other home brewing methods, especially for beginners who are still getting used to the idea of making their own beer.

Here are some of the advantages there can be for beginners who start out with a BIAB setup:

• Space limitations: Because BIAB brewing is done in a single vessel, this means that it can be done in much smaller spaces than other types of home brewing. If you have a clear counter in the kitchen big enough for a stockpot, you have enough space for brewing beer there. The small setup for BIAB means it is easier to fit into many areas of your home without being obtrusive.
• Small batch brewing: BIAB brewing is one of the best ways to make a smaller batch of beer for people who aren’t looking to make a gigantic brew. If you want to brew beer in a batch of six gallons or less, BIAB can be a great option since it is efficient for small batches.
• No measuring: If you use a home brew recipe, you’ll need to carefully measure in additives, malt extracts, and grains in order to make sure that the taste of the beer comes out like it’s supposed to. But using a BIAB setup means that all off the grains and extracts are already measured out for you in order to provide a good flavor profile. Think about it in terms of using a cake mix to bake a cake, rather than measuring the ingredients for the cake out from scratch.
• Cheap brewing: Compared to other types of brewing, BIAB brewing is cheaper not just because BIAB bags tend to be cheaper than buying the ingredients for a brew batch separately, BIAB brewing also requires less equipment. This means your entire brewing setup will ultimately be cheaper if you go with a BIAB setup versus a traditional home brew.
• Less equipment: Not only does BIAB brewing cost less to set up, the minimal equipment involved in running a BIAB setup is also advantageous to many people. Two major pieces of equipment that can be omitted when doing a BIAB brew are the sparge pot and the mash tun.
• Easier steps: Because BIAB brewing removes several steps involved in the home brew such as sparging, it makes the entire process simpler. This can be less intimidating for people who are getting started in brewing or people who don’t feel comfortable with a more complicated or nuanced process. Because brewing involves a lot of labor for an uncertain result, removing as much uncertainty from the process as possible can improve the chance of a good outcome.
• Easy to clean up: Because it involves fewer vessels and a smaller amount of space, cleaning up after a BIAB homebrew is a lot quicker and easier than cleaning up after different methods of homebrewing.

As you can see, there are tons of reasons why a BIAB setup can be a good choice for doing a brew, especially if you’ve never done one before.

They’re also a good option for people who are wanting to start small in the hobby—both in terms of space and of equipment—and work their way up.

Disadvantages of BIAB for Home Brewing Beer

While there are lots of benefits of using a BIAB setup for a home brew, there are some drawbacks to this setup too.

Here are a few of the disadvantages you may run into when you choose a BIAB setup:

• Grain bags are heavy: The grain bags involved in BIAB brewing can be quite heavy, especially once they’ve been saturated in the wort. Even though you won’t have to do a lot of repetitive lifting of grain bags during the process of brewing, you will have to do it at least a few times during the process. This may be more difficult for physically weaker brewers, brewers with conditions such as arthritis, or brewers with mobility issues.
• Bag brewing can lead to efficiency issues: Because BIAB brewing is a no-sparge method, it eliminates the step in brewing, which removes excess sugars from the wort prior to fermentation. This means that in BIAB brewing, you may end up with more residual sugars than you’d like in your beer. However, those BIAB setups that have a fine mesh bag can make up for the loss of efficiency by using a smaller grain of malts.
• Less customization: BIAB brews pretty much eliminate the ability of a brewer to come up with a beer recipe that is completely their own since it involves using a beer “preset” of grains and extracts rather than allowing the brewer to add these ingredients individually. While this consistency can be a boon for beginning brewers, it may stifle more advanced hobbyists.
• Big brewing pot needed: The entire brewing process with a BIAB setup occurs inside the brewing kettle, so the kettle itself needs to be large enough to hold the entire batch of beer at one time. This not only limits BIAB brewing to small batches, but it also means that you’ll need a heat source that is powerful enough to heat the wort through directly in the kettle.

There are a few drawbacks for using a BIAB in your home brew, but overall, there are more advantages to disadvantages for doing a BIAB brew, so it’s worth the shot if you’ve never attempted one.

Even if you usually do more complicated brews, you can still do a BIAB brew with less of the same equipment.

How Does Brew in a Bag Work?

At its core, BIAB brewing works in the same way that a traditional brew works—you heat grains, malt extracts, and other ingredients in a kettle for a specified amount of time, then remove the grain bag and allow the wort to continue to boil.

Boiling the grains and extracts renders starch sugars from the grain.

These sugars then undergo fermentation, which converts the sugar to ethanol alcohol, giving the beer its alcoholic content and contributing to its final flavor.

The BIAB setup keeps all of the grains and mash extracts contained.

Unlike traditional brewing, where ingredients are added individually to the brewing kettle and have to be strained and filtered out.

The BIAB setup removes the need to either rinse them out or filter the beer.

A Couple of Things to Watch Out For

The only way the astringency of the grains in the BIAB bag may negatively affect the brew is if there is a hole in the bag that lets any grain husks through.

The other issue with BIAB setups is that if the mash in the bag is ground too fine, this can lead to an excess of trub in the fermenter later.

Do You Need to Sparge with BIAB?

Sparging is the process that involves rinsing the grains multiple times in order to extract and remove as much excess sugar as possible.

This improves the final flavor of the beer and also lowers its specific gravity, making it less heavy and cloudy.

Sparging is one of the steps of brewing that is removed in the BIAB process.

You also don’t have to lauter when doing a BIAB batch, which is the process that involves separating the wort from the grain by recirculating the mash prior to sparging.

Some brewers argue that one of the major disadvantages of a BIAB setup is that you lose some efficiency of conversion when it comes to converting start sugars in the beer to alcohol.

But the fine mash that can be used in a BIAB setup largely off-sets this efficiency problem, so it’s still a great method for most brewers to at least experiment with.

What Are Recommended Bags for BIAB?

It can be a little difficult to find a good quality, reasonably-priced bag for a BIAB setup.

While you might be able to find some lower-priced bags that can get the job done, these bags may lack durability and can become torn during the transfer or boiling process, which in turn can leak grains into your wort that can negatively affect the final flavor and make the beer too astringent or dry.

Here are some traits that you’ll want to look for in a good BIAB grain bag: 

• Fine mesh You’ll want a BIAB grain bag that is made of a very fine mesh that allows for the transfer of chemicals such as start sugars but keeps the grain particles in the wort to a bare minimum.
• Economy: Some BIAB bags are over-priced and over-marketed while making a BIAB grain bag out of sewn curtains can hold just as much grain as one of the commercial bags while offering a good transfer of starch sugars too.
• Size: BIAB setups come in different sizes, but in order to increase the efficiency of your batch, you’ll probably want to get a bag to match the largest batch size you can reasonably handle with your home brew. Since there is a good deal of labor and time involved with each batch, you’ll want to maximize your results each time.

Here are a few of the commercial BIAB grain bags available on the market:

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Homemade Brew Bags

For those who aren’t that crafty, buying a commercial brew bag makes it a lot easier to get started.

But for people who can use a sewing machine, a much cheaper grain bag can be created from a variety of different meshed fabrics as long as they’re fine enough to prevent excessive bleed-through.

The Quality of Your Brew Bag Matters

One of the major advantages of buying a high-quality brew bag is that the bag is reusable, so as long as it is rinsed and cleaned well between uses, you should be able to brew with it over and over again.

Because of this, it may be more advantageous to invest in a more expensive brew bag that will last longer versus a cheap version, which may break down more quickly when exposed to heat and a heavy saturated load.

How Can You Improve Your BIAB Efficiency?

One of the biggest complaints with running a BIAB setup is that there can be a significant loss of efficiency in starch conversion, depending on the type of bag you use and how you conduct your brew.

Here are a few tips to try out when it comes to improving your BIAB efficiency :

• Finer grains: Running your grains through a mill multiple times to make them finer can help off-set some of the conversion efficiency issues caused by boiling your grains in a bag. The more finely the grains for the brew are ground, the more starches are released from them during the wort boiling process.
• Make sure that you have a good mesh on your bag. Using a coarse mesh may allow for a high level of conversion, but it will also dump a lot of grain particles in your brew, which can change the final flavor and can also leave you with excess trub during the fermentation process. On the flip side of that, if you choose a bag that has too fine of a mesh, you may end up with a clean-looking wort, but you’ll lose some of your flavor, alcohol content, and starch conversion.
• Sparge your brew. While using a BIAB setup removes the need to sparge or lauter your brew, it is still a process you can undertake even with a BIAB setup if you’re concerned about residual sugars that are left behind in the grain bag. However, adding a sparge step to your brewing process does remove a lot of the efficiency and convenience of doing a BIAB brew.
• Focus on beer recipes that account for lowered efficiency. Some beer recipes can be crafted even with lower efficiency levels, and these are the beers you should focus on making if conversion efficiency is a concern during a BIAB brew. Which beers are suitable for a BIAB brew are usually determined by the gravity of the beer that is desired (or how full-bodied it is) and the flavor—how sweet or astringent the beer turns out.

Even though BIAB brewing may be slightly less efficient than other brewing setups, there are many different steps you can take to help mitigate this brewing factor to increase your brew’s efficiency.

While these extra steps may not be necessary for many BIAB recipes, they can act as a refining process if you want to make your BIAB brew more nuanced and play with different flavors or additives.

Refining Your BIAB Setup and Technique

Once a brewer becomes more confident in their ability to follow the brewing process without making significant technical errors, they may begin to experiment more with adding extras to their BIAB bag or changing up the proportions slightly in order to yield a more refined result in the end.

Here are a few extra pointers for getting the best out of your BIAB setup (with or without sparging):

• Add your grains to the strike water, and not the other way around. You don’t want to pour water over the grains.
• Using a mash cooler can help you maintain the correct temperature for your brew. One of the issues with doing a BIAB setup is that it can sometimes be difficult to keep the temperature consistent, so using a cooler—even though it necessitates extra equipment—can help keep your results consistent.
• Use gloves for squeezing your BIAB grain bag. Getting some heat-resistant gloves can allow you to easily squeeze out residual wort from the grain bag before discarding the grains without burning yourself on the boiling hot wort.
• Make sure to stir the wort often (every ten to fifteen minutes) to make sure that there is not any temperature stratification during the boiling process. In small batches, it is easy to get varying temperatures within the boiling kettle depending on how close the wort is to the heat source, and this can cause inconsistencies in the final flavor of the beer.

Using a BIAB setup to brew beer at home isn’t very complicated compared to some other methods, so as long as you are meticulous and pay attention to your durations and temperature, you should end up with a drinkable result.

How to Clean a BIAB Bag

A major advantage of BIAB brew bags is that they can be used multiple times, but many new brewers may wonder how to effectively clean these bags so that they don’t carry residual starches or other debris from previous brews into the new batch.

Luckily, the process of cleaning a BIAB could hardly be simpler.

Here’s how you should go about it whenever the boiling process is complete:

• Remove used grains from the grain bag. These grains can be either composted into the garden for some high-quality compost or used to feed livestock like poultry or pigs if you have any.
• Thoroughly rinse the bag multiple times. Using a spray attachment at the kitchen sink is a good way to get those hard-to-extract grain particles out of the interior of the bag. It’s also a good idea to gently scrub the bag’s interior in your hands with one piece of the fabric against another to dislodge any particles.
• Hand wash the brew bag gently with a mild detergent. A few drops of dish detergent is usually sufficient for getting the brew bag sanitary without damaging the mesh or leaving residual soap. Be sure to rinse thoroughly after soaping.
• Wash in the washing machine. You can wash a grain bag on the gentle cycle of your washing machine if you’d rather not hand-wash it, but it’s a good idea to wash it alone rather than with other clothing or fabric unless you want to get grains on your other clothing.

Keep in mind that it isn’t a huge deal to get your BIAB bags spotlessly clean after each mash, since you’ll be boiling the bags again anyway, and this should remove any residual particles, bacteria, or other residue left over from previous brewing activities.

However, it’s a good idea to at least thoroughly rinse your bag to prevent any off-odors or other issues from developing.

One benefit of commercial bags is that they often come in multiple packs, so even if you end up with a brew bag that is starting to look tattered from multiple uses and washes, you should be able to easily replace it before it becomes a quality problem.

BIAB Brewing Is a Great Introduction to Home Brewing Beer

The reason that BIAB brewing has become so popular over the past several decades is that it makes the process of home brewing much more accessible to people who otherwise may have thought you low-key need a chemical engineering degree to pull it off.

In truth, brewing beer is not that difficult, and humans have been doing it for thousands of years.

If you’re interested in getting started with brewing beer at home, BIAB is definitely a great place to start!

Last update on 2024-12-16 / Affiliate links / Images from Amazon Product Advertising API