Very Low Efficiency

Yesterday I attempted a partial mash for the first time, I ended up missing my OG by a mile (target 1.067, actual 1.053). My calculated efficiency was ~30%. My method was not traditional and I am sure was the cause but I dot get exactly why.

I started by bringing 1.25 quarts per lb of water to a few degrees above mash temp. I then placed 4.5lbs of grain in a bag into the water - temp was low so I added a small amount of water to get temp to 154. I wrapped the pot in towels and put it in a large cooler, between this and the over 100degree ambient temperature I only lost 4 degrees in an hour. At an hour i lifted the bag and held until there were only a few drips leaving the bag, only gave it a slight squeeze. The resulting wort was sweet to the taste. I then put the bag into my brew kettle with nearly my full boil volume in the low 160s dunking it repeatedly and letting it sit for 10 minutes.

I the removed bag, put wort from mash into kettle and started boil as usual. I did NOT take a gravity reading at this time, rather only at the end post boil and after DME add.

what did I do wrong here, in my mind it seemed like a great idea and I was estatic to see the mash temp hold and the resulting wort be sweet but upset at the final gravity.

A few questions: Can you post your grain/extract bil? Did you do a full boil? Did you adjust your gravity reading for temp?

smokinj said:

A few questions: Can you post your grain/extract bil? Did you do a full boil? Did you adjust your gravity reading for temp?

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2 lb - American 2-row
1 lb Munich Malt - 10L
.50 lb Carafoam
.50 lb Caramel Malt 60L
.50 lb Melanoidin Malt

Yes, I did a full boil consisting of the wort I collected from the mash plus the "sparge" water and then a bit more to get me to my planned pre boil volume (I somehow lost a very little, probably absorbed into the grain). The gravity reading was taken post cooling, my wort was at 68deg so no correction was made.

In hindsight I really should have taken a reading before the boil, while I am certain it would have been way low there too now I just have to assume that is the case.

Hmm. How much extract? Seems like your process was good. The reason I asked about the full boil is that it's pretty common to get incorrect readings when adding "top up" water to the fermenter to acheive your desired volume. Only other possible issue I can think of would be a poor crush on your grain. It would almost have to not be crushed at all to hurt efficiency that bad, though. You can always boil up some more extract and add it to your fermenter to get the gravity that you wanted.

Even though it wash roomed as a full boil there is no comment as to whether the actual volumes were met or if top off was still required, this could still be an issue at hand. The crush can still be a concern as well. In addition, how much extract was used and what was the pre boil volume/post boil volume?

If top off water was used then the mix could be the culprit.

If top off water was not used in a full boil what was your intended into fermenter volume? and what was your actual volume into fermenter?

I started with 5lbs of DME, once I saw my gravity was so far off I boiled up another 1lb in a few quarts of water and added it to the fermenter.

Sorry, there was no top off water - my intended into fermenter volume was 5gal and I ended up with 5.25 into fermenter with .25 left in kettle. This was before adding the extra lb mentioned above.

The 2 row was crushed the day beffore at my lhbs and all of it was used. The rest of the grains were crushed by northern brewer at an unknown time, they were packaged 1 week before brewing for shipment to me but not sure when they were crushed.

well you can account for some of the loss of efficiency to the extra 1/2 gal of volume above your intended 5 gals. The crush could account for some of the rest.

The OG would be affected by the extra volume but not effenciency right? Assuming my OG stayed the same, and I increase the volume then my efficiency actually goes up does it not?

your recipe was calculated for 5 gal. you had an extra 1/2 gallon not accounted for in the recipe so the beer was diluted by an extra 1/2 gal. of water not boiled off.

sonex said:

your recipe was calculated for 5 gal. you had an extra 1/2 gallon not accounted for in the recipe so the beer was diluted by an extra 1/2 gal. of water not boiled off.

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^^This^^, that half gallon plus the probability of an inadequate crush equals poor efficiency and lower than expected OG.

As you move to AG you will find all these details play into every beer batch you make. Any variations in the process, volumes, crush, etc will have the potential to make or break a beer

When you added the grain to the strike water did you stir really well to break up the dough balls? If not, that could explain the poor efficiency. I've never tried BIAB, but I also think that you would need a great deal of dunking (or even another stir of the grains in the bag to dissolve the sugars trapped in the grains.

-a.

ajf said:

When you added the grain to the strike water did you stir really well to break up the dough balls? If not, that could explain the poor efficiency. I've never tried BIAB, but I also think that you would need a great deal of dunking (or even another stir of the grains in the bag to dissolve the sugars trapped in the grains.

-a.

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I stired well, made sure there were no clumps at all - a nice slightly watery oatmeal consistency.

I dunked the bag numerous times, then stirred with it sumberged in the sparge water and let it sit for 10 minutes.

Yesterday I attempted a partial mash for the first time, I ended up missing my OG by a mile (target 1.067, actual 1.053). My calculated efficiency was ~30%. My method was not traditional and I am sure was the cause but I dot get exactly why.

efficiency is measured pre boil gravity after the mash

After thinking about this a lot more than I probably should I came up with two other potential issues.

1. Testing my hydrometer with distilled water I came up with varying numbers. It became evident that dropping it in and waiting for it to settle could produce a consistent yet wrong reading. Dunking it with my finger and letting it bob back to a stable place too resulted in inacurate readings. I found that spinning it in the tube and allowing it to come to rest consistently produced a 1.000 reading. So its entirely possible my reading was wrong from teh start by a few points.

2. The Melanoiden, Carafoam and Caramel were all orderd crushed in 1lb increments. I only needed 1/2 lb of each so I split the lb by volume using a measuring cup - its entirely possible that I got more hulls and less seed. This would not account for the huge miss but could play a part.

I am thinking in the end there is no single answer, the two items above in conjunction with an elevated volume of wort probably all played into the "miss".

I am going to try brewing again real soon using grain crushed same day, and pre-measured before crushing along with very strict gravity and water measurements along the way along with adjusting my burner so that I end up boiling off exactly what I planned to do (its amazing how much I can vary boiloff by simply boiling more vigorously)

chmarkham said:

efficiency is measured pre boil gravity after the mash

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What gives you that impression? You can measure efficiency at three distinct portions of the process.. in the mash, in the kettle preboil and in the fermenter. They all tell you important things about the process if you're in troubleshooting mode.

Bobby_M said:

What gives you that impression? You can measure efficiency at three distinct portions of the process.. in the mash, in the kettle preboil and in the fermenter. They all tell you important things about the process if you're in troubleshooting mode.

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brewhouse efficiency is how much sugar you get out of the grain mash and pre boil gravity is the same thing. og and fg is different then brewhouse efficiency

I thought that was mash efficiency and brew house efficiency was how much sugar got to the fermenter.

Gartywood said:

I thought that was mash efficiency and brew house efficiency was how much sugar got to the fermenter.

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You are correct.

chmarkham said:

brewhouse efficiency is how much sugar you get out of the grain mash and pre boil gravity is the same thing. og and fg is different then brewhouse efficiency

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Brewhouse efficiency is the percentage of potential sugar that makes it into the fermenter. Mash efficiency is the percentage of potential sugar that makes it into your kettle, which is what you seem to be referring to.

Nit picking but mash efficiency is a measure of conversion and diffusion, i.e. taking a gravity sample directly out of the mash and using the total water addition as the dilution figure. This is a measure of how much sugar you got into the mash wort.

Mash/Lauter takes into account how good you were at getting the sugar water out of the mash.

Brewhouse is the aggregate of all the processes and considers system losses post boil.

That's why I said there are three different places you can test for efficiency where the figures are going to be different.

Bobby_M said:

Nit picking but mash efficiency is a measure of conversion and diffusion, i.e. taking a gravity sample directly out of the mash and using the total water addition as the dilution figure. This is a measure of how much sugar you got into the mash wort.

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Ha! Nit pick accepted. I would think a potential issue with this approach is that water to grist ratio would have a significant impact on the "measured" result vs the actual result. Less so, the moisture content of the grain, but those would both impact the percentage of water absorbed in the grain. Not saying it might not be a useful number, particularly if using the same grain bill and water:grist ratio over consecutive batches.