BIAB - How can I improve the brewing efficiency?

[Mihai]

Hi,

I only started brewing 4 months ago and even if today i brewed my 4th BIAB beer I still have some things I'm not sure about.

I adapted my recipe to a 15 litres water volume (my pot is only 20 L) and didn't add any other amount of water. I did sparge the grain bag, but with wort from the pot. When transferring to the fermenter I got 9 litres, making my efficiency 60%. Probably i will lose another litre on the trub.

What I'm still uncertain about, is if for a 15 litres recipe the amount refers to the initial volume, before adding the grains or the expected final volume. My guess is that it refers to the initial volume based on the low OG resulted: 1.042, instead of 1.050 as per the recipe.

How could I improve my efficiency using the same equipment?

Should I use 20 litres recipes (grain content) and only 15 litres mashing water and sparge by adding warm water resulting a higher final wort volume?

Could this be a solution? Because I always end up with very little beer, usually about 8 litres of bottled beer from a 15 litres initial water volume.

Thanks in advance.

 

[LLBeanJ]

Recipe batch size would be the volume of wort into the fermenter.

Sparging with wort isn't going to do much for you. You need to use water. It does not need to be hot water, ambient temp works just as well.

With a 20L kettle you should be able to mash with something like 12-15L to leave room for the grain, then sparge with the remainder to achieve your pre-boil volume. Pre-boil volume should be your 15L batch volume + expected boil-off (~4L?). It will be a tight fit and you'll have to watch for boilovers until the hot break clears, but should be doable. After the wort has been boiled and cooled, you should have 15L of wort to dump in the fermenter.

 

[McKnuckle]

Efficiency calculations are based on a combination of sugar content and wort volume. If you magically got 100% of the sugar out of your grist, but you lost a lot of liquid during your process, your efficiency would be much lower than 100%. Brewers focus a lot on the sugar part, but the volume loss counts, too.

You should be losing a controllable and reasonably predictable volume of water at each step during BIAB.

During the mash, the grain absorbs some water than never gets reclaimed. The absorption rate is about 0.293 quarts per pound (this value is in BeerSmith and I've found it to be fairly accurate). After the mash is complete, lift the bag and place it on a colander that can be suspended over the pot opening. Don't sparge at all. Let the bag drain as you bring temp up to a boil. Some squeeze it, but I don't.

The next significant loss is the volume evaporated during the boil. This depends on various factors, but since you're probably indoors, ambient temp and humidity are not major factors. The diameter of your pot, and the intensity of your boil, are the important ones. I have a wide pot that loses nearly a gallon an hour. I have a narrow, tall pot that loses less than 0.5 gallons an hour! Big difference. Figure out your situation and plan future brew days accordingly.

Finally, after the boil you have two kinds of efficiency to consider, and brewers often throw the numbers around without mentioning which kind they are referring to. "Ending kettle" efficiency is before you transfer to your fermenter. "Brewhouse" efficiency is after you transfer. So you can see that brewhouse uses the same sugar content that is present in the ending kettle wort, but it adds an additional volume loss to the equation.

Consider that for a moment... you might have great efficiency before you transfer, but if you have lots of trub or don't transfer well for some reason, the brewhouse number can drop dramatically. For this reason, I prefer to use ending kettle efficiency in my recipes, because it focuses on the brewing part (sugar extraction and boil). Those factors are what help me formulate a recipe. The actual quantity of wort in the fermenter is somewhat less important to me - within reason of course.

Recipe tools often have an "ending kettle" target as an option rather than an "into the fermenter" target. To do as I've outlined, you'd use the former.

Sorry for the ramble... hopefully something there will make sense.

 

[Mihai]

Thanks for the answers. So it's the other way around than I thought (regarding the water volume). But in my last brewing case (15 litres of water before mashing for a 15 litres recipe resulting in 9 litres of wort in the fermenter) the gravity is still below the recipe's predicted OG. In this case if I would have had 15 litres in the fermenter (by sparging or by having a higher initial water volume) then the OG would have been very low. This is what confuses me. It seems i did ok-ish on the sugar part but lost a lot on the volume part.

 

[chickypad]

Thanks for the answers. So it's the other way around than I thought (regarding the water volume). But in my last brewing case (15 litres of water before mashing for a 15 litres recipe resulting in 9 litres of wort in the fermenter) the gravity is still below the recipe's predicted OG. In this case if I would have had 15 litres in the fermenter (by sparging or by having a higher initial water volume) then the OG would have been very low. This is what confuses me. It seems i did ok-ish on the sugar part but lost a lot on the volume part.

If you used enough grain for a 15 L recipe, but only ended with 9 post boil and were still low on OG, then no you didn't do okay on the sugar extraction part. I'm very confused by all your descriptions, can you post your actual recipe and gravities and volumes throughout? Where are you getting the 60% efficiency from?

 

[Mihai]

The recipe I used I self adapted from other recipes found online, without using Beersmith, so I might have begun wrong already. A reason for the low sugar content might be that the wheat malt was grinded with a spice grinder, not a malt mill (my malt mill got stuck after grinding the pale malt). Another reason might be because the entire malt was made at home and probably that's why it didn't reach it's full potential. (Is there a way to find out the gravity potential of homemade malts? Something like mashing a small water/grain quantity and reading it's OG?)

The recipe in this last case is a bananaweizen:

I had 15 litres of water in the brewing pot and mashed in at 68'C for an hour:
1.6kg (3.5lbs) Pale malt
1.6kg (3.5lbs) Wheat malt
0.2kg (0.44lbs) Crystal malt
The preboil SG was 1.030. I removed the grains after sparging with wort(no new amounts of water were added) and brought the wort to a boil and added:
25g (0.55lbs) Tettnang hops (60)
450g (1lbs) peeled bananas (10)
1 tsp Irish Moss (10)
After boiling for an hour, i cooled it down in less than 10 minutes and the gravity at 20'C was 1.042.

I calculated the 60% efficiency from having 15 litres preboil out of which only 9 litres went in the fermenter.

 

[McKnuckle]

When I put the recipe into Brewer's Friend (brewersfriend.com), and adjust it a bit to fit my own BIAB equipment profile, it works out to:

Mash with 3.92 gallons of water (14.84L)
Grain absorption loss = 0.54 gallons (2.04L)
Boil-off during one hour = 0.88 gallons (3.33L)
Amount left in kettle = 2.5 gallons (9.46L)

Leave a bit of trub behind, and there you have it - 2.375 gallons (9L) into the fermenter.

I think your water volumes make plenty of sense. Your efficiency is low because of poor sugar extraction. At 70% ending kettle efficiency, you should have pre-boil gravity of 1.046 and OG of 1.077. I used Crystal 40 because you didn't specify the Lovibond rating of your crystal. You're getting under 40% efficiency. The pre-boil gravity of 1.030 is notoriously inaccurate; wort needs to be mixed very thoroughly - I think it was probably a bit lower in reality.

What is "homemade" malt? You grew the barley, malted it, and kilned it at your own farm?? I think you just mean you milled it. People will tell you that the milling is critical to efficiency. My guess is that's your main culprit. I'd also look into stirring frequently during the mash (use direct fire to keep the heat at your target temp).

Anyway, at 1.042 and full attenuation you'll have a wheat beer with about 4% ABV, which is on the low side but perfectly okay for the style.

 

[Mihai]

What is "homemade" malt? You grew the barley, malted it, and kilned it at your own farm?? I think you just mean you milled it.

I bought both the barley and wheat and malted it at home: sprouted it until the acrospire reached ~75% length of the grain, kilned it to 40-50'C for 24 hours and crushed it with a roller mill, which i managed to repair today.
For the first 2 beers I made, I used malt bought from an online shop which was shipped already crushed and by comparing it to the malt crushed by my mill it was quite similar. The problem was with the wheat malt yesterday which i grinded in the spice grinder.

 

[McKnuckle]

Well that's impressive! But I have no idea what compromises might have been made in the preparation compared to commercially available malt. Maybe someone else will chime in.

 

[chickypad]

Looks like McKnucle has done a nice job laying out the numbers for you. As he (she?) noted, efficiency is the measure of how well you extracted sugars from the grain and collected those sugars. It's not to do with how much water you lost in the process.

Kudos to you for malting your own. Do you have numbers from your first 2 batches using commercial malt? I suspect the discrepancy is probably related to the home malting process, especially if your crush looked okay. No idea how you would go about getting a malt analysis, there are other folks on here doing home malting though maybe you can search for some help. At least if you continue doing batches with your own malt and can get consistent numbers you should be able to figure out how to calculate a grainbill to hit your gravities.

 

[Dovage]

I do biab only. For 5 gallons of beer I mash in with 3.5 gallons to 4 gallons of water. I usually lose a 1/2 gallon to 3/4 gallon to grain absorption. I then batch sparge my grain bag with enough water to get my preboil volume up to 6 gallons. It doesn't really matter how much water you sparge with but the more you rinse your grains the more sugar your getting. Then I usually do a 90 min boil to get down to 5 gallons. ( this time varies depending on your pots evaporation rate). Then check your gravity. If you hit it great, if not you can always boil longer to bring it up.
Hope this helps

 

[emyers]

If you want a better efficiency you can batch sparge. Cut your initial water volume by a gallon or two, once you mash out place the grains into an additional pot/cooler/bucket and add that extra gallon or two at 170-180f for your second batch, let it sit for 10 min and mash out again. Also a longer boil would bump your efficiency since it would be a weaker solution pre boil. Boiling off additional volume will get the OG right back where u want it, or higher.

 

[emyers]

Pretty much exactly what dovage said.

 

[Mihai]

I'm preparing just now another batch and I'll get back with the results, this time taking all your advices into consideration and using the roller grain mill for all grains.
I adapted my recipe using BeerSmith, which is a great software, I only found out about it after doing the last batch. It looks like this:

Batch size: 11L
Boil size: 16L (which will also be my mashing volume, the equipment I use doesn't allow more than this, but I will sparge with 2 litres of hot water -equiv of the grain absorption)
Recipe is:
1.33kg Wheat Malt
1.33kg Pale Malt
0.30kg Caraaroma (this one is bought, not homemade)
10g Tettnang (60)
13g Tettnang (60)

I am considering of doing 2 identical batches which will ferment together, so I'm aiming at around 22 litres in the fermenter. Is that a common practice? Should I take special care at something in particular?

I will put the yeast after the second batch gets in the fermenter. I will be using Danstar Nottingam yeast which I washed off the yeast cake of a previous batch. What quantity should I use in this case? I was thinking of around 25 grams.

 

[Allergic2hops]

There is lots of great information here and I am by no means an expert, but I am an engineer and numbers make sense to me. I will tell you my approach and see if you can use any of it to help your process out.

I have a 9 gal (34 ltr) pot. For a smash that I am brewing I use 12 lbs of grain. I typically start out with 7 gal of water in my pot (which is way different than Beer Smith). Here is why. I pay attention to the volume of the pot by measuring the depth of my wort at all stages. I have a metal yard stick I bought a the local DIY store. The internet is full of volume converters I just use the volume of a cylinder and divide by the cubic inches for the volume used. I use gallons, that number is 231 cu in per gallon. That gives you your volume in gallons per in volume. For my pot to have a finished volume of 5.5 gal I need a final wort volume of 9.5".

Like I said I start with 7 gal of water adjusted to 7.0 pH, I mash for 45+ min. The reason I say that is because a very wise poster on HBT let me in on a secret. Once I get to 45 min I start watching the clarity of the wort and stop watching the time. The starch to sugar conversion should lead to crystal clear wort. I check by pulling the bag to the side and view the wort on the other side of the bag. Took me a couple of tries but once I finally saw it I stopped watching the clock. Different mash temps give different conversion rates. So just watch your wort. No need to mash for 75 min if your grain and temp yielded clear wort at 50 min.

Now with that said, I pull the bag and let the first runnings out. Then I put it in a strainer and let it finish draining. While its doing that I measure the wort depth and prepare my sparge water so that I hit 6.5 gallons to begin my boil.

I boil for 45 min and flame out to quickly check my volume, depending on the humidity of the day I may evaporate more or less than I need. I adjust my last hop addition accordingly and at flame out I have 5.5 gal sitting in my pot ready to be cooled with wort chiller added 10 before flame out. According to Brewers Friend my last BIAB brew yielded an efficiency of 89.74%. My OG was 1.071 @ 5.5 gal.

This is the method I used and it yielded a fantastic all grain Pampion ale that made the holidays. At 5.7 percent, it made everyone smile. Hope this helps.

Thanks goes out to the poster who gave me that tip, it changed everything for me, I just don't remember your username. Just passing it on ... paying it forward.

 

[chickypad]

I am considering of doing 2 identical batches which will ferment together, so I'm aiming at around 22 litres in the fermenter. Is that a common practice? Should I take special care at something in particular?

I will put the yeast after the second batch gets in the fermenter. I will be using Danstar Nottingam yeast which I washed off the yeast cake of a previous batch. What quantity should I use in this case? I was thinking of around 25 grams.

Yes you can certainly combine two batches in the fermenter if your equipment doesn't allow you to mash and boil them all at once. Just keep the fermenter sealed or covered while you are brewing the second batch. Mrmalty includes an option to calculate how much harvested yeast slurry you need to pitch. It's in mls, not sure what the equivalent would be in grams.

 

[Mihai]

I did the recipe I posted above but only one mash, not a double one. The grains were crushed accordingly and I stirred them in the bag about every 10 minutes. After 50 minutes at 68-69'C i did a mash-out to 73-74'C for 10 minutes, moved the bag in a different pot, sparged it with 2 litres of water,left it to mash another 10 minutes then drained the bag and added the wort back to the brewing pot, having again 16 litres which i brought to a boil. Before the boil the gravity was only 1.020 before sparging and 1.018 after adding the water resulted from sparging. But the reading was made at around 60'C, so it's not the most accurate.
After 60 minutes of boiling I still had about 13,5 litres in the pot so I continued boiling it for another 40 minutes until I got about 12,5 litres, cooled it to 22'C resulting in 12 litres of wort in the fermenter at 1.043 OG, compared to 1.050 the expected OG. Now after 12 hours there's about 2 litres of trub in the fermenter.
My personal conclusions are that the grains don't reach the full potential of a commercial malt and i'll have to add extra grains for a recipe and it seems that I'm not loosing that much water when boiling, since I reached the batch volume only after almost 2 hours. I don't know how the hops were affected by this: first hops were boiling 100 minutes and second 20 minutes.
My next batch I'll try doing the exact same recipe but with +20% grains (only the homemade ones) and less boiling water, around 14 litres.

 

[chickypad]

I did the recipe I posted above but only one mash, not a double one. The grains were crushed accordingly and I stirred them in the bag about every 10 minutes. After 50 minutes at 68-69'C i did a mash-out to 73-74'C for 10 minutes, moved the bag in a different pot, sparged it with 2 litres of water,left it to mash another 10 minutes then drained the bag and added the wort back to the brewing pot, having again 16 litres which i brought to a boil. Before the boil the gravity was only 1.020 before sparging and 1.018 after adding the water resulted from sparging. But the reading was made at around 60'C, so it's not the most accurate.
After 60 minutes of boiling I still had about 13,5 litres in the pot so I continued boiling it for another 40 minutes until I got about 12,5 litres, cooled it to 22'C resulting in 12 litres of wort in the fermenter at 1.043 OG, compared to 1.050 the expected OG. Now after 12 hours there's about 2 litres of trub in the fermenter.
My personal conclusions are that the grains don't reach the full potential of a commercial malt and i'll have to add extra grains for a recipe and it seems that I'm not loosing that much water when boiling, since I reached the batch volume only after almost 2 hours. I don't know how the hops were affected by this: first hops were boiling 100 minutes and second 20 minutes.
My next batch I'll try doing the exact same recipe but with +20% grains (only the homemade ones) and less boiling water, around 14 litres.

Sounds like you're getting it dialed in. I don't see anything obvious in your process that should account for a huge decrease in efficiency (though with BIAB you can increase your crush and see). I don't usually stir the mash but that's mainly because I don't want to lose temp. I also don't usually mash out when BIAB'ing just for simplicity, but again doing one is not a detriment. You could play around with mash/sparge ratios but many folks BIAB the full volume with no sparge and lose very little if any efficiency. I agree it likely comes down to the fact that your home malt has different potential than commercial grains. The only other thing I would ask is if you know anything about your water, or are checking pH at all. It's not the biggest factor that comes to mind troubleshooting efficiency, but if you have extreme water it could be playing a factor.

As far as your hops, changing the 60 min addition to 100 will be no big difference, most of the IBU's come after 60 min anyway. If the 20 min addition was to be a very late addition then you will get less aroma and a bit more bittering. If it was to be a hoppy beer you could always dry hop it for more aroma.

 

[Mihai]

The only other thing I would ask is if you know anything about your water, or are checking pH at all. It's not the biggest factor that comes to mind troubleshooting efficiency, but if you have extreme water it could be playing a factor.

I didn't do any tests to the water but I'm bringing it from a mountain spring, I don't use tap water when brewing, so I guess it should be ok from this point of view.

I learned and understood a lot of new things in the process from you guys and i really appreciate it. Thanks a lot. Cheers!