Poor Efficiency on a CAP?

Hey all,

Just brewed a batch of CAP from the recipe in the latest BYO. The LHBS was out of flaked maize, and so I have read that instant grits work in a pinch. So that's what I did. The grain bill was as follows:

4.4 lb domestic 2 row
4.4 lb pilsner malt
3.3 lb flaked maize (instant grits for me)

The mash temp was supposed to be 149F, but my strike temp was a little low. I hit 149F initially, but my cooler mash tun dropped to 141F at the end of the 75 min mash.

Here's my question: the math for my efficiency came out to 45%. Is this because the low mash temp or incomplete breakdown of the corn? The iodine test was good, so conversion was complete of what was available. Should I have boiled the instant grits a bit first, or was just adding them to the mash good enough? I guess I'm confused as to why the efficiency was SO low. Any help would be great!

Edit: iBrewMaster said my OG should have been 1.067 with a 70% efficiency. Mine was measured at 1.051, which corresponded to the 45% I said above.

There are a lot of things that can effect efficiency. If you read and follow the following link it should help you identify and improve your efficiency on your next brew.

http://braukaiser.com/wiki/index.php?title=Troubleshooting_Brewhouse_Efficiency

How was your crush? That is the largest factor in efficiency. Do you have your own mill?

onthekeg said:

How was your crush? That is the largest factor in efficiency. Do you have your own mill?

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The crush was good - it was done at the LHBS, and they've been fantastic in the past. I don't have my own mill, but would love to win one in the Giant Giveaway!

BobC said:

There are a lot of things that can effect efficiency. If you read and follow the following link it should help you identify and improve your efficiency on your next brew.

http://braukaiser.com/wiki/index.php?title=Troubleshooting_Brewhouse_Efficiency

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I guess I'm wondering, from experience, with all other factors aside, would the corn in the mash or the low mash temp have a greater impact on the final extraction efficiency? I'm sure my process isn't ideal, but those were the two areas that I think lacked the most in my last brew session.

If they weren't instant grits, you probably should have done a cereal mash. A ton of threads on here on how to conduct one.

JPFuller said:

If they weren't instant grits, you probably should have done a cereal mash. A ton of threads on here on how to conduct one.

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Yeah, I used the instant grits per the threads on the forum. Should have been just fine. Tasted the wort and it didn't have an overly 'corny' flavor, so that's why I was wondering about an incomplete corn conversion.

On a better note, I used a yeast starter for the first time on this CAP and it reached high krausen much faster than my last lager. Less than 24 hrs and it was chugging away!

With the mash temps you posted, I suspect your initial temp of 149 dropped off pretty fast if you ended at 141. My guess is that you actually mashed in the mid to low 140's and your efficiency took a hit based upon those low temps. You need to take a temp on the mash after 5-10 minutes when the temp has stabilized...very common to have a false high reading after initial mash in as the grain has not absorbed all of the heat yet.

wilserbrewer said:

With the mash temps you posted, I suspect your initial temp of 149 dropped off pretty fast if you ended at 141. My guess is that you actually mashed in the mid to low 140's and your efficiency took a hit based upon those low temps. You need to take a temp on the mash after 5-10 minutes when the temp has stabilized...very common to have a false high reading after initial mash in as the grain has not absorbed all of the heat yet.

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You know, I figured that was the biggest reason why, but I wanted to run it by the forums to see if there were any other ideas. In the winter, everything is a bit cooler in the house, especially if I bring my mash tun cooler in from outside. I usually have great efficiencies with my system, so I was surprised how low it was this time. I guess I'll have to overshoot the calculated temp a little bit in order to hit the desired mash temp next time. Thanks!

If the temp was the cause it would result in a very slow conversion, or an incomplete conversion, leaving behind starches that would have failed the iodine test. My guess is that either the starches weren't fullyy extracted from the grits, the ppg of the frits was estimated too high, or the addition of the grits caused lautering inefficiencies.

pohldogg said:

If the temp was the cause it would result in a very slow conversion, or an incomplete conversion, leaving behind starches that would have failed the iodine test. My guess is that either the starches weren't fullyy extracted from the grits, the ppg of the frits was estimated too high, or the addition of the grits caused lautering inefficiencies.

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You know, that's a good point, too. Flaked maize is a lot bigger than grits, and would be less likely to clog things up. The grits are pretty fine to begin with compared to flaked maize, so that could have bunged up the lautering a bit.

Knowing some of this now, I can't wait to try the Classic American Pilsener again!

I figured out my issue. Stupid mistake, but it's probably worth sharing because I bet it's happened before.

In the brewing software (iBrewmaster), I chose grits as the adjunct. I should have used flaked maize in the recipe because, like the INSTANT grits I used, it has been pre-gelatinized. After changing the ingredients from 'grits' to 'flaked maize', the contribution to the OG matched up and everything was okay.

It seems that the same amount of old-fashioned grits, done properly in a cereal mash, will contribute more to the OG than the same amount of instant grits or flaked maize. At least that's how I'm interpreting this.

Glad you found your solution, but going back to what was discussed before... mash temp doesn't really affect OG, right? OG is all based on dissolved solids in the wort, so as long as you sparge properly and had a good crush, you can hit your expected OG. Temp does affect what those solids are (starches v. sugars), but doesn't necessarily affect how much you are able to extract. Your FG will change based on temp, but overall extraction shouldn't change... right?