Terrible Efficiency

[Pataka]

After my first BIAB all-grain experience, I decided I would repeat the entire process with the exact same recipe second time around, to try and either improve on the errors I made last time, or figure out where I may have gone wrong.

My first batch had two issues that I noted. First, my mash temperature was too high. The calculator I used said to start with strikewater at 74C, but this made a mash that was hotter than I wanted. The second issue I had was I missed my intended gravity, and the wort was weaker than I would have liked.

The second time around, I resolved the first issue, but repeated the second. So it's clear I have an efficiency issue in my system that I need to sort.

I'm a stovetop brewer, so I only do small batches with all grain. I started with 9L of water, and added 3kg of crushed pale ale malt. I mashed at 67C for 60 minutes, and did a brief sparge using water at roughly the same temperature. By the time the boil was complete, I added water to top up to 9L, then checked the gravity. I was hoping to get 13L to 1.053, so this was intended to be an intermediate check. However, at 9L, I was already down at 1.047. I added no more water, and cooled the wort down to pitching temp, then pitched.

But my point is, 3kg of malt should yield a MUCH higher gravity than 1.047 for 9L of wort. BrewersFriend's recipe calculator says that I am getting roughly 46% efficiency. That's utter rubbish, and I need to figure out why.

What I don't know for certain is how accurate my thermometer is. I used the temp probe on my InkBird temperature controller to get the mash temp. Who knows how accurate it is. I wrapped the mash tun in blankets whilst mashing, and the dropped by about 0.5c throughout the process.

Something is wrong somewhere. I'd love to know where.

 

[Oginme]

First thing to check is the crush of your grain. Take a small handful of the grain into a cake pan and spread it around so you can see the kernels well. They should be fractured with some dust and particles free of husk. Take some of the kernels which look whole and they should fracture easily with a little pressure between thumb and index fingernail. If you find you have a good number of kernels which are still hard and solid, then you are a poor crush and the water cannot penetrate to dissolve the starches so the enzymes can break them down. With BIAB, don't be too worried about over crushing your grains, since it is nearly impossible to get a stuck sparge.

Next, How big is your pot? Does 9 litres plus grains fill the pot up? At 3 kg of grain with a 75% efficiency, you should be getting somewhere in the range of your expected 1.053 sp gr. If there is a limit to how much you can put into your pot for the mash and boil, this would reduce this greatly. If you are limited in your pot size, maximize the boil volume by sparging in a second pot with as much of the make up water as will fit into your pot for the boil. The water does not need to be hot, but you should get the bag into the second pot and open it up to stir the grains so that the sparge water can penetrate thoroughly to rinse off the sugars from the grain.

Third, make sure your bag is big enough to fill your pot entirely. If you are constricting the grains when you mash, then the water available to solubilize the starches will be limited as well. The solubility of starch (and later sugars) is not unlimited. Along with that, when you add the grains into the pot, you should put the bag in and then pour in the grains. Stir until you think all the grains have been wetted through and there are no signs of dough balls or clumps of grains. Then stir for a few minutes more before covering for the mash.

You don't mention if you are squeezing the bag. If not, then you might want to consider it to reduce the amount of water (and sugars) which are still in the grains. If you don't want to squeeze, use a colander on top of your pot and allow the bag in the colander to drip back into the pot as you heat up towards your boil. If there is not enough room for the colander to fit comfortably, place it in a bowl and allow it to drip there before transferring the drippings back into the pot.

I'd recommend starting there to see if that changes anything.

 

[Pataka]

First thing to check is the crush of your grain. Take a small handful of the grain into a cake pan and spread it around so you can see the kernels well. They should be fractured with some dust and particles free of husk. Take some of the kernels which look whole and they should fracture easily with a little pressure between thumb and index fingernail. If you find you have a good number of kernels which are still hard and solid, then you are a poor crush and the water cannot penetrate to dissolve the starches so the enzymes can break them down. With BIAB, don't be too worried about over crushing your grains, since it is nearly impossible to get a stuck sparge.

I used up all the grain I had, so can only look at the spent grains. Probably not a great deal of use, but I'll still have a look tomorrow in decent light to see how whole some of the kernels appear to be.

Next, How big is your pot? Does 9 litres plus grains fill the pot up?

No. the pot holds about 16L in total. Water plus grain during the mash occupied about 75% of the total volume. Do you think I should try a thinner mash next time?

Third, make sure your bag is big enough to fill your pot entirely. If you are constricting the grains when you mash, then the water available to solubilize the starches will be limited as well. The solubility of starch (and later sugars) is not unlimited. Along with that, when you add the grains into the pot, you should put the bag in and then pour in the grains. Stir until you think all the grains have been wetted through and there are no signs of dough balls or clumps of grains. Then stir for a few minutes more before covering for the mash.

I thought this may have been where I went wrong last time. Last time I made the newbie mistake of filling the bag with grain before lowering it into the pot. I then spent the next 5-10 minutes breaking up the dough balls. I'm sure I never got all of them. This time, I used a scoop to add the grain into the strike water, stirring as I did. It took about half the time. I still gave it a good stir once all the grain was in.

The bag is made for a brew pot that will do 23L batches, so it definitely doesn't constrain the grain in any way.

You don't mention if you are squeezing the bag. If not, then you might want to consider it to reduce the amount of water (and sugars) which are still in the grains.

I do that to some extent. I have a large plastic storage crate that I use to transfer the grain bag into after mashing is complete. I use it to sparge into, then pour the remaining wort into the pot. I then squeeze the bag a little once it has cooled slightly, and transfer what comes out into the pot.

At this stage, it's sounding like either the crush of the grain isn't fine enough, or I need to do a thinner mash than I'm doing. In both cases (this and the previous batch) I started with a relatively small amount of water, so the water to grain ratio might be the issue.

 

[Oginme]

You are correct that looking at the spent grains at this point may not give you much, unless you find a good number of intact grains which still have some 'tooth' to them when bit or pinched.

I would go for the thinner mash. BIAB as developed by the Aussies is a full volume mash, with no sparge at all.

Between this and your planned changing of the grain feed into the mash, you should be on the right trail.

 

[D7Brewing]

I am new to home brewing since starting about a year ago I have only done all grain BIAB. I have had the same problems you are having. First thing I started doing was squeezing the bag like it owed me money. I get every last drop I can out of that thing. I know you will read that that will lead to tannins in the beer but I have not found that to be true. But I have had a brew or two where even that didn't fix the issue. I suspect that the issue in these cases is PH. I am going to start monitoring that on my next batch. One other culprit may also be the type of grains you are using. Since you are only doing 2-3 gallon batches you aren't using large quantities of grain. If you are then using a lot of grain with low diastolic (spelling) power then you could be having trouble with your conversion during mash. You need to check your pre boil gravity to see if this is an issue.

 

[RM-MN]

The top 3 reasons for poor efficiency in brewing beer are:
1. the crush
2. the crush
3. the crush

All other causes fall far below those three.

 

[madscientist451]

What was the volume and gravity after the boil but before you added the top up water?

 

[soccerdad]

Don't be afraid to mash longer. Monitor everything for 60 minutes then go run an errand. Many of the early adopters of BIAB advocate a 90 minute mash. But as RM-MN noted above, a finer crush will often get you more points in less time.

 

[beerguy707]

Mash a bit longer and don't be afraid to open it up and stir it around intermittently. Just keep an eye on your temp and turn the heat on if you start to lose heat.

 

[wilserbrewer]

The top 3 reasons for poor efficiency in brewing beer are:
1. the crush
2. the crush
3. the crush

All other causes fall far below those three.

Agreed, I think the fourth leading cause of poor efficiency would be "the crush"

If the Inside starch of the kernel is not well exposed, it's difficult to convert to sugar and be released to the wort!

 

[Pataka]

Looking at the 'spent' grains, there were a few kernels that didn't seem to be particularly open. They were all able to be opened by chewing, but you'd expect that to be the case after an hour soaking.

I decided I'd do a second mash with the grain last night, and managed to get another 2L with the same gravity. I had some leftover hops, so went ahead and did a full boil with them as well, while the remaining liquid boiled away. The overall efficiency I calculated at around 55%, which is climbing up to where I'd like it to be.

I think I've got enough to go on from here. I'll order my next batch of grain to be double-crushed, and do a mash with as much water as I can fit into the pot with the full grain bill in there. It might not quite make it to 13L, but it's a start.

 

[Brew_G]

Good advice throughout the thread.

Since crush is so important to those of us who BIAB, I'd suggest investing in a mill if it's within your budget. Buying bulk grain and being able to mill it gives you all the control you need over your crush, allowing you to adjust or re-mill when you need it.

It's a higher up-front cost, but you'll come out ahead in the long run from buying in bulk.

 

[kh54s10]

The overall efficiency I calculated at around 55%, which is climbing up to where I'd like it to be.

I think I've got enough to go on from here. I'll order my next batch of grain to be double-crushed, and do a mash with as much water as I can fit into the pot with the full grain bill in there. It might not quite make it to 13L, but it's a start.

55% is still really low.

Just adding more water might be a bad idea.

You need to have the proper amount of grain for the water you are using. For instance if you use x amount of grain at 55% efficiency to Y amount of water. Then brew another with x amount of grain, still at 55% efficiency but with Yx2 of water you will get a much lower gravity wort.

If you can swing it get a mill of your own. Corona style mills are $25 -$50 USD. on this side of the pond

 

[leightonp]

This isn't a solution to poor efficiency but a bypass. My BIAB efficiency is terrible and I have a baby on the way so buying a mill is out. I take my gravity reading and add dme to hit my numbers.

 

[doug293cz]

If your BIAB efficiency is lower than you would like, and you can't swing your own grain mill, then there are a few things you can do to improve your efficiency:

• Double crush to minimize the number of uncracked grains.
• Mash longer to get more conversion from the poorly crushed grain.
• Squeeze the bag aggressively to get as much of the wort (and sugar) out of the grain as possible. (Tannins come from high pH, not squeezing.)
• Do a batch sparge with 60% of your total water for strike, and 40% of total water for sparging. Squeeze the bag well before the sparge, and after the sparge.
• Make sure your mash pH is in the range 5.2 - 5.7 (5.4 - 5.5 is better.)

Brew on

 

[eadavis80]

I buy PH stabilizer and it has helped my efficiency. I know others will site studies that say it's worthless, but for $1.25/5 gallon batch, my efficiency went from embarrassing to something I can easily live with. I have also found that stirring at the 30-minute mark seems to help. It's easy to remember for me because it takes me 30 minutes to heat up sparge water on my stove so I just do those two things then and I do okay. Good luck. As long as the beer tastes good and you get DECENT efficiency, to me, that's all that matters. I'd rather it taste good and finish at 5% than taste bad and finish at 5.75%.

 

[doug293cz]

I buy PH stabilizer and it has helped my efficiency. I know others will site studies that say it's worthless, but for $1.25/5 gallon batch, my efficiency went from embarrassing to something I can easily live with. I have also found that stirring at the 30-minute mark seems to help. It's easy to remember for me because it takes me 30 minutes to heat up sparge water on my stove so I just do those two things then and I do okay. Good luck. As long as the beer tastes good and you get DECENT efficiency, to me, that's all that matters. I'd rather it taste good and finish at 5% than taste bad and finish at 5.75%.

You'd save money and get somewhat better results by learning how to use gypsum, calcium chloride, lactic acid, and baking soda (only for dark beers) to adjust your pH, rather than using the stabilizer that doesn't really work (and adds extra salts that can adversely affect flavor.) Cost is more like $0.25 per batch. Get the Bru'n Water spreadsheet or use one of the on-line water calculators. You don't have to fully understand the water chemistry, just learn how to use the tool.

Brew on

 

[RM-MN]

This isn't a solution to poor efficiency but a bypass. My BIAB efficiency is terrible and I have a baby on the way so buying a mill is out. I take my gravity reading and add dme to hit my numbers.

Wait a minute. If you can afford to buy grains, hops, and yeast to make the beer, you can afford a mill to make it more pleasurable too. Mills don't have to cost a lot. This is what I've been using and I usually exceed 85% efficiency. http://www.discounttommy.com/p-189-...er-for-wheat-grains-or-use-as-a-nut-mill.aspx

 

[soccerdad]

I hand grind my grains .. can get a hand mill (which IMO works well for BIAB) for about $25. You can tweak it to a fine grind.

https://www.amazon.com/dp/B000U5NZ4I/?tag=skimlinks_replacement-20

Admittedly, I am never in a hurry on brew day, and I don't have a child on the way, so your needs may differ.

Takes me about 20 min to grind for a 5G batch.

 

[eadavis80]

You'd save money and get somewhat better results by learning how to use gypsum, calcium chloride, lactic acid, and baking soda (only for dark beers) to adjust your pH, rather than using the stabilizer that doesn't really work (and adds extra salts that can adversely affect flavor.) Cost is more like $0.25 per batch. Get the Bru'n Water spreadsheet or use one of the on-line water calculators. You don't have to fully understand the water chemistry, just learn how to use the tool.

Brew on

Never picked up on any adverse flavors with the PH stabilizer and while the tool probably makes it pretty easy to understand all those ingredients, the lazy part of me thinks it's too much work to save $1.00...

 

[leightonp]

Gonna have to look into a corn meal grinder. Thanks for the idea. All I've seen at the brew shop and online looking were the roller mills

 

[Bobby_M]

Or find a grain supplier that will actually ask you what kind of crush you want.

 

[Black Island Brewer]

Wait a minute. If you can afford to buy grains, hops, and yeast to make the beer, you can afford a mill to make it more pleasurable too. Mills don't have to cost a lot. This is what I've been using and I usually exceed 85% efficiency. http://www.discounttommy.com/p-189-...er-for-wheat-grains-or-use-as-a-nut-mill.aspx

+1
That's the mill I use too. "Let no kernal get left behind!"

 

[wilserbrewer]

Yes, if your on a budget, it can be said that you cannot afford to not buy a mill, given the price break buying grain in bulk.

 

[petrolSpice]

I've found that mash thickness has a big impact on my BIAB efficiency. If my mash is too thick I'll add water to thin it out and then opt for a more vigorous boil to get the volume back down.