A Craft Beer & Brewing Magazine reader recently asked us the following question:
I want to transition to all-grain brewing. Brew-in-a-bag looks like an inexpensive way to get into all-grain, but are there any disadvantages?
Brew-in-a-bag (BIAB) is an excellent way to start all-grain brewing on a budget. In fact, my home system is a Blichmann BrewEasy, which is essentially a fancy stainless BIAB system. For the average extract brewer, all you need to purchase to step up to BIAB is a large pot, a grain bag, and some kind of propane burner.
The concept behind BIAB is to perform the mash and boil all in a single large pot. You heat up some water in a large pot, add a fine-mesh grain bag, and mix in the grains to get them to your desired mashing temperature. Then you maintain that temperature for an hour or so to complete the starch-to-sugar conversion. When you are done, just lift the grain bag out, which separates the grains from the wort, and then boil the wort. The rest of the process—adding hops, boiling, chilling, and fermenting—is the same process you use for extract brewing.
If we compare BIAB to a traditional brewing system where you have three separate vessels for mashing, boiling, and heating water, the cost savings can be substantial. In addition, BIAB usually saves you some time as you don’t have a lengthy sparging process (just lift out the bag), and there is less equipment to prepare and clean. So, a BIAB system saves you both time and money.
As far as disadvantages, some BIAB systems do have slightly lower mash or brewhouse efficiency, though the same can be said for many traditional systems. I don’t consider this a big issue at the homebrew level since we’re often talking about a pound or less of extra grain if your system has lower efficiency, and in fact, the grain crush has a larger impact on efficiency in most cases.
Some brewers say that BIAB can lead to a slightly “thinner-tasting” beer. This may be due to the high water-to-grain ratio you use when adding all the water up front in the mash, which can result in a more complete sugar conversion and higher attenuation during fermentation. However, the Germans have been doing traditional decoctions at high water/grain ratios for hundreds of years and still produce some great malty beers. As I said, I brew on a BIAB system and have not had an issue with this.
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