Often a hot topic for debate, the Brew-In-A-Bag (BIAB) technique is one that claims roots in Australian homebrewing, and is gaining a lot of ground worldwide. We often use this technique while brewing indoors, and feel that it’s a great way for homebrewers to transition to all-grain brewing. All it takes to get started is a brew pot and a few BIAB bags! No cooler, no sparging, and far less mess!
THE CONCEPT: BIAB technique is one where the brewer uses crushed grain in a porous bag that allows permeability of liquids within the brew kettle without the transfer of grain from within the bag to the wort. Most brewing steps are the same. What changes, and what we consider highly advantageous are the following points:
1) NO NEED TO SPARGE! The most common method of BIAB is to begin with all the water you’ll need in your pot from start to finish (water-grist ratio explained later). This means that if we are planning on a five gallon batch in the fermenter, we will add all the water we need into our pot, treat the water, add the grain, mash, mashout (we find it helps raise our OG by ~5 points), remove the grain, boil, cool, transfer to fermenter, done! While some brewers do in fact sparge while using the BIAB technique, it seems rather counter-intuitive to the ease of the technique, not to mention that we’ve tried sparging and found our efficiency did not really improve, but also made for a longer brew day, more potential for mess and injury, and a pain when treating water with salts for either removing chlorine/chloramine or adjusting PH and hardness. This also reduces your brewing footprint, as you do not require extra equipment (such as a mash-tun cooler), and you don’t need to worry about performing a “vorlauf”. Furthermore, you need not to worry about grain ending up in your boil. One technique we’ve adopted is to stir and press the grain bags with our mash paddle to really infuse the grain with the hot liquor (hot water).
2) EASIER CLEAN-UP! Never have I met a homebrewer who really loves to clean after making a batch of beer, but if you want to be a serious brewer, you must be serious about cleaning. A great thing about the BIAB technique is that when your mash (and optional mashout) is complete, you can simply remove the grain bags, squeeze them (more on this hot topic below), and drop them into a bucket or sink to cool before simply opening them and transferring your grain into your organic waste bin (also great for baking with or feeding your livestock if you have any). Anyone who has used a cooler to batch or fly sparge will know that it’s a moderate pain to clean (especially when brewing indoors), and so this is just another attribute to the minimalist brewing system that BIAB affords.
3) FASTER BREW DAY! Brew-In-A-Bag really does streamline your brew day, thus shortening it. Filling and tying-off the bags is quick, emptying/cleaning the bags is quick, no cooler to clean, and no sparging. We find this shaves at least an hour off our brew day!
BIAB EFFICIENCY: We have found that efficiency does decrease to some extent when using this technique. This is due to the grains not being rinsed after the mash is complete. Usually we end up at around 70% efficiency, rather than 75%-80% when batch or fly sparging. The reduction of gravity points is certainly a point of contention when brewers consider the BIAB technique, but here’s our response: BIAB is really only a technique used on a homebrewing scale, and a minimal loss of efficiency can be compensated by the addition of a relatively minimal amount of extra grain. Here is a breakdown of the cost of extra grain to match the efficiency of batch/fly sparge:
Schönwetter Brewing Efficiency Stats:
Efficiency loss of BIAB vs Batch/Fly Sparge: 5%-10%
Gravity points lost with a 5%-10% efficiency loss: 3-6 (eg. 1.047 BIAB vs 1.050 Batch sparge vs 1.053 fly sparge)
Gravity points 1lb of base malt adds: 3 (eg. to raise 1.047 to 1.050)
Cost of 1lb of base malt grain where we live: ~$1.50
As you can see, on a homebrewing scale, it costs us an extra $1.50 to match the efficiency of batch sparging per batch of beer. If a ~5 gallon (~19 litre) batch of beer gives us ~55 x 341ml bottles of beer. Spread that extra cost of the 1lb of base malt grain, you are looking at an extra cost of ~$0.03 per bottle of beer. An extra 3 cents per bottle in exchange for less equipment, less cleaning, and equally good beer. That’s our $0.02 worth.
SQUEEZING THE BAG: If you have an hour to burn, do a Google search on whether one should squeeze the bag with the BIAB technique. We spent well over an hour researching this, and then we brewed a bunch of batches alternating between squeezing the bag and not squeezing the bag. Cause of concern: Extracting tannins from the grain by squeezing. Final verdict: Squeeze the bag! Not only are the grain bags filled with wort goodness, it seems that the amount of required force to extract tannins from the grain is beyond the heroics of even the mightiest homebrewer. We have seen zero negative effects by squeezing the bag, and, rather, end up having more wort to boil down, which is a good thing. We find the best way to get the most squeeze out of you bag (most bag for your buck?), is to lay your mash paddle horizontally over the rim of your pot, and start wrapping the bag around the handle of the paddle (think of winding rope on a well shaft to raise a bucket). Some people will pipe up that this will create HSA (Hot Side Aeration) — First, we don’t believe in it yet (have never seen any negative effects from a little splashing). Second, if you are so concerned about HSA, put the grain bags into a bowl, one at a time, and squeeze the wort in there before transferring that wort (ever so gently) back into your pot.
WATER-GRIST RATIO: Some feel that the concept of a proper Water-Grist (grain) ratio is important for enzymes to properly convert grain starch into grain sugar. When using the BIAB technique, one way to maintain the typical 1.0-1.5 quarts of water per pound of grain ratio (~1L-1.5L of water per pound of grain) is to perform your mash with the amount of water to produce this ratio, followed by adding the remaining water after the mash is complete. Currently we brew without paying attention to this ratio, starting with total water at the start of the mash. This is for ease of operation, but will be a technique we will experiment with shortly. Quite likely a proper water-grist ratio will be incorporated into our brew day, but we do not see any ill-affects thus far from not incorporated it. Software such as BeerSmith has tools to calculate water additions for this purpose.
HOW TO SAVE EVEN MORE MONEY: Homebrew shops mark up their inventory so that they can stay in business and continue to provide us homebrewers the products that we demand. Upon saying that, these BIAB bags tend to be overpriced. What we found is that these bags are just paint strainer bags, and so we just go to a paint store to purchase them. In comparison, one of these BIAB/Paint Strainer bags at a Homebrew shop costs ~$8.00, and ~$1.50 at a paint store. Sometimes you might even find a paint store attached to a homebrew store which makes for a very convenient brewing supply trip in the car.
HOW TO BREW IN A BAG: Either purchase your pre-milled grain or mill the grain yourself. If you are milling the grain yourself, a trick we learned is to stretch the grain bag over the opening of a plastic brewing pail and then mill directly into the bag (less mess). Because the grain is being held in bags, you can mill more finely, thus increasing efficiency without risk of a stuck sparge…because there is no sparge! Depending on the size of the BIAB bags you are using, you want to fill them loosely. If you pack the bags too densely, you will encounter poor utilization/efficiency. When we brew a typical 5 gallon/5% abv. batch, we are using three or four grain bags in our pot. This keeps the grain loose which enables greater surface area between grain and hot liquor (water). Dough-in at your desired temperature, and compensate for the temperature loss caused by adding the grain (should be the same as when brewing via other techniques). Ensure that when doughing-in, you stir thoroughly to diffuse the grain to avoid dough-balls (just like a regular mash). Mash as usual. Mashout as usual. Squeeze the bags, remove the bags, bring wort to a boil and continue your brewing process as usual.
CONCLUSION: Since we incorporated the BIAB technique into our brewing arsenal, we have found that we are brewing a lot more. Not only is there the ease of spent grain handling, clean-up is easier, there is less equipment required, and the loss of efficiency is rectified by adding $1.50 worth of grain for a 5 gallon batch of beer. If you are looking to get into all-grain brewing, we HIGHLY recommend starting with this process. The only thing we noticed is that when doing a step-temperature infusion (mashing at different temps) is that the bags can scorch on the bottom of the pot when turning the element on HIGH to raise the temperature. This can be combated by placing an aluminum or stainless steel colander upside-down inside your pot to keep the bags off the bottom of the pot (we just use a false bottom in our pot). Alternatively, first raise your liquor (water) to your desired mash temp, turn down the heat (we find that our stove will maintain mash temp indefinitely at between 2-3 on our stove dial), and dough-in at that point.
Some pots will allow a grain bag to be stretched over the rim. There are some over-sized bags on the market, permitting all the grain to be stirred within the bag. The problem is that not only are they pricey, but lifting a single bag filled with all your wet grain is very heavy, messy, and potentially dangerous. Also, you can squeeze a lot more wort out of smaller bags than attempting to do so with one large bag. Squeezing the bags after they have been sitting in mash temperatures for 1+ hours makes them very hot. The best way to combat this is to pull out the bags, let them cool for a while, and then squeeze them. We are impatient, so we put on two sets of Blichmann brewing gloves and squeeze the bags right after pulling them. Remember: Safety first, sanitation second, and great beer third!