How to balance base and crystal malt ratios with low extraction efficiency?

[Shenanigans]

Hi All,

Normally I do BIAB in a 8 gallon electic kettle and sparge with about 2.5 gallons.
With about 70% efficiency this works fine to get 5 gallon beers up to an OG of about 1.080.
However if I want to aim for something with an OG around 1.100 then I have to do a no sparge mash in a 13 gallon cooler. This works fine, I have the process nailed and hit my numbers and volumes but the efficiency goes down to 50 to 55%. I could probably increase the efficiency by sparging but it would take a while for me to nail that process. So for now I will continue to do it this way.

I see in Beersmith that color of the worth shoots up for the same OG as the efficiency goes down. This indicates that the efficiency of the extraction from the malts that need to be mashed take a bigger hit than the malts that don't need to be mashed resulting in the ratio of mash sugars to non-mash sugars (or roasted) going up which increases the color. This can be a problem when trying to clone a beer because a tried a trusted recipe is probably developed with a mash efficiency of greater than 70%.

My question is, is there some way to calculate how to change the ratio of non-mash to mash malts so that you end up with a similar beer from a 50% system to one with a higher efficiency or am I overreacting and it's not really a problem?

Thanks

 

[Electricbrew]

Not an answer to your question exactly; but another possible option I’ve heard of (if you have time) is to mash half the grain, then sparge up to strike volume again and heat to strike temp and use this wort to mash the second half of the grain. Sparge that to your pre boil volume and go from there. I haven’t done it yet (but planning to try soon) so I’m not sure how well it works or how it plays into efficiency, but I’ve heard of others doing it that way. Maybe someone else will chime in...

 

[redllama]

When you start to get that high of an OG your efficiency is always going to go down. I can't remember exactly where I saw it but I know that after a certain point there is a pretty linear relationship to increased OG and falling efficiency. I know that on my system my base 5% stout gets 78-80% efficiency but my Imperials tend to be more in the 60-65% range.

 

[doug293cz]

When you start to get that high of an OG your efficiency is always going to go down. I can't remember exactly where I saw it but I know that after a certain point there is a pretty linear relationship to increased OG and falling efficiency. I know that on my system my base 5% stout gets 78-80% efficiency but my Imperials tend to be more in the 60-65% range.

The decrease in efficiency with increasing grain bill weight (at a constant pre-boil volume) is monotonic (if the rest of the process stays the same.) That means it does not start decreasing at some threshold, but is a smooth continuous decrease. The decrease is entirely due to decreasing lauter efficiency, since a larger grain bill will absorb and retain a larger fraction of your wort. Lauter efficiency is equal to 100% - percent of total wort retained by grain (for a no sparge process. It's a little more complicated if you sparge, but the principle is the same), so if retained wort goes up, lauter efficiency goes down.

Here's a chart that shows how lauter efficiency varies for various sparge counts at two different wort retention ratios (grain absorption rates.)

Brew on

 

[FatDragon]

Count me another vote for iterative mashing. Mash half of the grain, then use the wort as strike water to mash the second half. Better efficiency, it's easy, and you don't have to worry about possibly needing to adjust your recipes.

Or just sparge in the cooler. It's not rocket science, after all. If low efficiency makes you worry about your recipe design and dumping some water in your cooler will bump up your efficiency, why wouldn't you just do that?

 

[RM-MN]

Normally I do BIAB in a 8 gallon electic kettle and sparge with about 2.5 gallons.
With about 70% efficiency this works fine to get 5 gallon beers up to an OG of about 1.080.

My question is, is there some way to calculate how to change the ratio of non-mash to mash malts so that you end up with a similar beer from a 50% system to one with a higher efficiency or am I overreacting and it's not really a problem?

Why are you getting 70% efficiency with BIAB and a sparge step when many of us can get 80% no sparge and quite a bit higher with sparge. Correct that problem and you won't have to deal with a 50-55% efficiency with a big beer. Start with the crush. BIAB can work with a much finer crush than most LHBS will provide. That means you need to get your own mill or if you already have a mill, tighten it up. Crush quality is the biggest factor in efficiency.

 

[redllama]

Thanks @doug293cz for correcting me with your chart. I had remembered seeing it a while back and couldn't remember all the specifics but I just remembered that as amount of grain/OG went up efficiency went down.

 

[Smellyglove]

One trick you could do, if you have the room for it in the BK, is find a lower OG recipe you've done, see what the ratio between mash and sparge water is, and use the same ratio in the bigger beer. This works.

For instance (just random numbers here). If low OG recipe is 10L mash and 10L sparge, and bigger OG beer calls for 15L mash and 5L sparge, add more sparge water so the ratio will be equal again. So the bigger beer would have 15+15, this means you'd need to boil for 10L "longer". Then you *should* ballpark the efficiency somewhere around the efficiency of the lower OG beer.

 

[Shenanigans]

Hey guys thanks for the replies.
A lot to consider there, I'm pretty busy at moment but will look into your suggestions when I get a chance.
Have a few days of brewing planned at the end of the month so I can experiment a bit then.

 

[doug293cz]

One trick you could do, if you have the room for it in the BK, is find a lower OG recipe you've done, see what the ratio between mash and sparge water is, and use the same ratio in the bigger beer. This works.

For instance (just random numbers here). If low OG recipe is 10L mash and 10L sparge, and bigger OG beer calls for 15L mash and 5L sparge, add more sparge water so the ratio will be equal again. So the bigger beer would have 15+15, this means you'd need to boil for 10L "longer". Then you *should* ballpark the efficiency somewhere around the efficiency of the lower OG beer.

Yeah, this works, since efficiency is a function of Grain Wt / Pre-Boil Volume (see my chart above.) The down side is that an extra 10L of boil is more than 2.5 gal so you're looking at increasing the boil time by ~2 hrs, or more. Pick your trade-offs.

Brew on