Brew-in-a-bag (BIAB) is a simplified all-grain brewing technique that developed about a decade ago among Australian homebrewers. Whether you’re new to brewing, an extract brewer looking to jump to all-grain batches, or an experienced all grainer who wants to speed up the brew day, BIAB offers an attractive alternative to traditional methods.
Process
As the name suggests, brewing in a bag involves brewing in…well…a bag. In traditional brewing rigs, grain is mashed in a mash-lauter tun, after which time wort is drained into the boil kettle. Either in batches or as a continuous process, the grain is rinsed with sparge water from a hot liquor tank to wash additional sugars from the grain bed.
Brewing in a bag obviates the need for such a complex setup by using the boil kettle itself for the mash. The brewer lines the kettle with a large, sturdy mesh bag to contain the grain, and the grain is mashed using the full volume of water needed for the batch, plus a bit extra to account for absorption. When the mash is complete, the bag is lifted out of the kettle and allowed to drain completely. The wort is then boiled, hopped, and chilled as in traditional systems.