Today I'm returning to the subject of BIAB specifically as I've just finished brewing a black IPA and am very disappointed with my "numbers" (read OG).
I am committed to BIAB as the best way for me to brew, but I'm learning that there are several aspects of BIAB that present unique challenges as compared to the traditional Single Temperature Infusion method.
They are:
1) Mash Temperature Control,
2) Correct grain crush fineness, and
3) Effective wort extraction from the grain bag.
Mash Temperature Control - The BIAB method presents a challenge in maintaining consistent temperature throughout the vessel. This is due to the fact that unlike traditional all-grain techniques that use a cooler with no heat source for a mash tun, BIAB typically uses either a propane burner, or electric brewstick as a heatsource available during the mash process. This requires that a buffer zone of water be used to prevent the bag from burning on the bottom of the vessel. This can result in significant temperature differences between the bottom of the vessel and the mash. Furthermore, the brew bag (typically made from voile) combined with the grains act as a barrier to the natural flow of water throughout the vessel/grains.
To address these challenges, the BAIB'er needs to do a few things. First, in a set up such as mine (below) where a digital controller tracks the wort temperature, make sure that the thermocouple/temperature probe is in the buffer zone, or close to the bottom of the vessel. Here is where the water will be the hottest, and this is where you want to monitor temperature so that you don't get it too hot.
[On a side note, when I started with BIAB, I heated my water to 13 degrees over the desired temperature assuming that the grains would cool things down to the desired mashing temperature (This is the what traditional AG brewers experience when using a cooler). My experience with this setup has been that the grain causes very little temperature drop. I have not documented the actual drop, but I know it's a lot less than 13 degrees.]
Second, ensure frequent stirring of the mash to encourage circulation of the water throughout your grain bag, and also to even out the temperature.
Grain Crush/Fineness - My local brew shop owner likes to tease me about being a BIAB'er, and when I purchased my grain bill for this black IPA, he asked me if I wanted him to crush it (knowing that I like a finer crush than his mill is set for). I let him go ahead, and unfortunately I did not re-crush it on brew day.
All went smoothly with my electric BIAB set up on brew day. This was the first time I used my "upgraded" control box with a digital temperature controller, and it did fine.
The OG on this fine recipe was supposed to be 1.070, but in the end I had achieved only 1.054. I think the coarser crush contributed to my low OG. From now on, I will re-crush at least once, as the worry of a stuck sparge is not an issue with BIAB. I may even try wet milling (spraying the grains a bit in an effort to keep the hulls from splitting apart). I had heard of this technique, but recently saw it done on a YouTube video here.
Ideally, you want as much surface area of the crushed grain to be in contact with the water during the mash time. Just as crushed ice cools a drink faster than larger cubes, finely crushed grains will be converted more efficiently because more surface area of the grains is available to the diastatic enzymes to act on.
Effective Wort Extraction from the Grain Bag - One of the upsides of BIAB is that you don't have to sparge. This is also one of the downsides, because even though most of the wort drips out of the bag,
I am committed to BIAB as the best way for me to brew, but I'm learning that there are several aspects of BIAB that present unique challenges as compared to the traditional Single Temperature Infusion method.
They are:
1) Mash Temperature Control,
2) Correct grain crush fineness, and
3) Effective wort extraction from the grain bag.
Mash Temperature Control - The BIAB method presents a challenge in maintaining consistent temperature throughout the vessel. This is due to the fact that unlike traditional all-grain techniques that use a cooler with no heat source for a mash tun, BIAB typically uses either a propane burner, or electric brewstick as a heatsource available during the mash process. This requires that a buffer zone of water be used to prevent the bag from burning on the bottom of the vessel. This can result in significant temperature differences between the bottom of the vessel and the mash. Furthermore, the brew bag (typically made from voile) combined with the grains act as a barrier to the natural flow of water throughout the vessel/grains.
To address these challenges, the BAIB'er needs to do a few things. First, in a set up such as mine (below) where a digital controller tracks the wort temperature, make sure that the thermocouple/temperature probe is in the buffer zone, or close to the bottom of the vessel. Here is where the water will be the hottest, and this is where you want to monitor temperature so that you don't get it too hot.
My keggle setup - note possible temperature differences possible if thermocouple is not in the buffer zone, or regular stirring is not done.
[On a side note, when I started with BIAB, I heated my water to 13 degrees over the desired temperature assuming that the grains would cool things down to the desired mashing temperature (This is the what traditional AG brewers experience when using a cooler). My experience with this setup has been that the grain causes very little temperature drop. I have not documented the actual drop, but I know it's a lot less than 13 degrees.]
Second, ensure frequent stirring of the mash to encourage circulation of the water throughout your grain bag, and also to even out the temperature.
Grain Crush/Fineness - My local brew shop owner likes to tease me about being a BIAB'er, and when I purchased my grain bill for this black IPA, he asked me if I wanted him to crush it (knowing that I like a finer crush than his mill is set for). I let him go ahead, and unfortunately I did not re-crush it on brew day.
All went smoothly with my electric BIAB set up on brew day. This was the first time I used my "upgraded" control box with a digital temperature controller, and it did fine.
Upgraded Brewstick Control Box
The OG on this fine recipe was supposed to be 1.070, but in the end I had achieved only 1.054. I think the coarser crush contributed to my low OG. From now on, I will re-crush at least once, as the worry of a stuck sparge is not an issue with BIAB. I may even try wet milling (spraying the grains a bit in an effort to keep the hulls from splitting apart). I had heard of this technique, but recently saw it done on a YouTube video here.
Ideally, you want as much surface area of the crushed grain to be in contact with the water during the mash time. Just as crushed ice cools a drink faster than larger cubes, finely crushed grains will be converted more efficiently because more surface area of the grains is available to the diastatic enzymes to act on.
Effective Wort Extraction from the Grain Bag - One of the upsides of BIAB is that you don't have to sparge. This is also one of the downsides, because even though most of the wort drips out of the bag,
