All-Grain Brewing in a Bag
Your first thought on this term might be that this is the simplest form of brewing possible. Perhaps something like open the bag, sprinkle in fairy dust and drink the beer? But what the title of this issue’s column really refers to is a simple, equipment-light method for brewing all-grain beers. In essence you simply add all the brewing water to your boiling kettle and bring it to the right temperature either on the stove or (preferably) with a propane burner. Then you add the crushed grain held in a sturdy coarse mesh bag, stir well and adjust the mash temperature, let it sit for one hour until finished and remove the bag, allowing it to drain into the kettle. All you have to do then is add the hops to the wort, boil, cool and ferment in the usual way.
Pros
The first great advantage of this technique is that the “traditional” set-up for all-grain brewing of hot liquor tank, mash tun and boil kettle is no longer required, and the sparging step has been eliminated. You need only one kettle. You can also buy a suitable bag for about $5 from a homebrew supplier. And apart from the cost there is an obvious saving in space required for the setup. Since you do not have to carry out a sparging step the whole process may also take less time than the normal all-grain procedure. As such the method offers a good way to venture into all-grain brewing, and if you like the beer it produces you can always upgrade your equipment later, as wallet and space demands allow.
Another perk is that you don’t have to worry about a stuck mash tun with this method, so you can mill your grain more aggressively to get better efficiency.
Cons
Since all the brewing water must be added at the start, you need a kettle big enough to handle this. How big? Well, if you want to make a 5 US gallon (19 L) brew, you need to collect around 6 US gallons (23 L) of wort, assuming that about 1 US gallon (3.8 L) will be lost in the boil. The grain will retain between 1 and 2 gallons (2.8 to 7.6 L) of liquor, depending upon how much grain you are using and on how well the bag is drained. That means a volume of at least 8 gallons (30 L), so that when you add in the grain, you will need a kettle with more than 10 gallons (38 L), and most protagonists of the method advocate a 15-gallon (57-L) kettle.
Then there is the question of brewhouse efficiency. As you do not sparge, the liquor held in the grain is actually wort. That means there is some loss in yield compared to the more normal mash/sparge method. Just how much you lose will depend upon how well you can drain and squeeze the bag after mashing. Some users suggest that this loss is only around 5% over normal mashing, and can easily be allowed for by increasing the total grain bill by 5% — a trivial increase in cost. But it does mean that you must check the wort gravity before adding the hops. That way, if you get a lower gravity than you aimed for, you can reduce the quantity of bittering hops and keep the beer balanced. Don’t be afraid of the calculation it is just a simple proportional change. Keep in mind that the collected wort has a greater volume than the finished wort, though.
So, suppose your recipe called for an original gravity (OG) of 1.050, and you collected 6 US gallons (23 L) at 1.037 and you expected to lose 1 gallon (3.8 L) in the boil. Then your OG at 5 gallons (19 L) would be (37 x 6)/5 = 1.044, and you are (6/50) x 100 = 12% below target. So simply add 12% (or about 1⁄8) less bittering hops at the start of the boil. Of course, if you are making multiple additions of hops at various intervals bittering calculations become much more complicated than I can deal with here. Also, don’t be worried about adjusting the amount of hops called for at the end of the boil — their effect on bitterness is relatively small and decreasing them by one-eighth will not have a noticeable effect on bittering, but may give less hop character than you wanted.
There is another question you may be wondering: will you get good conversion of the starch to fermentable sugars, given that you shall be using a much thinner mash than is normal? The standard method of infusion mashing requires about 1.3 qts. (1.2 L) of water per lb. of grain. But in the bag method let’s assume we are using about 10 lb. (4.5 kg) of grain and adding 8 gallons (30 L) of water; that is 32/10 = 3.2 qts. (3.0 L) water per lb. (0.45 kg) of grain, or just about three times as much as in the standard method. Now that is a big difference numerically, and it will affect the conversion. The normal thick mash tends to result in a higher level of non-fermentables in the wort, whereas as a thin mash results in a more complete conversion of starch to fermentable sugars. In other words beer from the thick wort will have more body or mouthfeel than that from the thinner wort. But the amylase enzymes themselves are degraded faster in a thinner mash, so the exact effect of using such a thin mash is one that you will have to work out for yourself. If the first beer you make this way is too thin tasting, then add, say, an extra ½ to 1 lb. (0.23 to 0.45 kg) of crystal/caramel malt, Special B or Victory® malt which will give some non-fermentables to the beer and boost its body. Simply increasing the mash temperature a couple of degrees, as is often done with thick mashes may also help, but be careful as higher mash temperatures can result in a more rapid degradation of the enzymes. The thin mash should give more complete breakdown of the grain starch so that you should not have any unconverted starch in the wort. Finally, because the enzymes are degraded rapidly their action will be complete in 10 to 15 minutes, so mashing for longer than that will not affect the fermentability of the wort.
An important consideration in this method is the bag itself. The mesh should be fairly coarse, but not so coarse that it cannot hold in the wet grain. And it must be sturdy enough to hold the wet grain without any risk of splitting, because that will create a stupendous hot and sticky (and dangerous) mess, so be sure to buy a suitable bag from a reputable supplier.
The bag must obviously be big enough to fill the pot, and to hang over the edge so that it can be securely fastened to the rim of the pot with spring clips. It should also be supported at the bottom with something like a metal trivet so that it is insulated from direct heat applied to the bottom of the kettle. If you don’t lift it off the bottom you will scorch part of the mash. I also recommend heat-resistant, non-moisture absorbent gloves since you are going to have to lift it partly out of the kettle and squeeze it to get out as much liquor as possible.
Step by step
1. Set up kettle on the heater, placing the trivet or other support on the bottom.
2. Put the bag in place, allowing it to just hang over the rim and use spring clips to fix it firmly in place.
3. Start adding the water and begin heating once you have a gallon or so into the kettle. Turn up the heat as you add the rest of the water. The amount of water will depend on your recipe, but you will need 8–9 gallons (30–34 L) of water for a 10-lb. (4.5-kg) grain bill.
4. When the water reaches strike temperature (about 10 °F, or 5.5 °C above required mash temperature), turn off the burner and add the grain. Stir the mash well to avoid clumping. This is generally much less of a problem with US 2-row pale malts than with their British counterparts.
5. When the mash is thoroughly mixed, check temperature, and apply heat (if required) to reach target mash temperature.
6. Mash for 60 minutes, adjusting the temperature at intervals as required.
7. When done, place a clean bucket close to the kettle, unclip the bag and lift it out of the water. Hold the bag above the level of the liquid while it drains into the kettle. For larger batches with bigger grain bills, rig a ladder or a pulley to hang the bag to drain and squeeze into the kettle. Apply some squeezing by rolling the neck of the bag tightly, using gloves as I have recommended earlier. This is the hard part of the procedure and how long you allow the bag to drain will depend upon both your strength and your patience!
8. Put the bag in the bucket, and start heating the wort, adding any extra drainings from the bucket after the bag has stood there a further 15 minutes or so.
9. When you have all the wort together check its volume (you did calibrate your vessel, didn’t you?), and check its specific gravity. Adjust hop rate, if necessary, as described earlier, and boil for 90 minutes.
10. At end of boil, siphon wort off trub, cool, pitch with yeast and ferment, rack and bottle or keg as usual.
Summary
Starting with simple equipment, and becoming acquainted with the requirements of all-grain brewing before spending money on more sophisticated gear is the best way to go. And in that respect, brewing in a bag is a simple and effective way in to all-grain brewing. You can build from there to a more complicated (and expensive) system if you wish.
