Inexplicable drop in mash efficiency

I can't figure what went wrong in my last mash. I probably would have shrugged it off except that it's the first time I tried 5.2 PH stabilizer.

I brewed a regular brew I've done several times, that I've been getting 75% efficiency out of.

11lbs of 2-row US malt
12oz 80L
8oz Cara-Pils

I step mash in 15 qts at 104F - 30 mins, 140F - 40 mins and 158F - 20 mins.
I slow sparge at 168 for 1 hour.

With this process I regularly get a 5.5 gallon result of 1.060 - about 75% efficiency.

I thought I'd try adding the PH stabilizer to see if I got a better mash.

Out of the boil, I had only 4.5 gallons, so I checked my gravity before I intended to top off at 5.5 gallons. My gravity was only 1.054 at 4.5 gallons - that works out to a mash efficiency of 55%. (I just pitched at this).

What could have happened? I shook the wort well, and double checked the final gravity (because I was so surprised). The step temperatures were good - and the mash well stirred. I calibrated the hydrometer for temperature. The grain is from the same bag as my last three brews of this recipe. The only difference was the 5.2. I used 1.2 table spoons for a sparged final wort volume of 7 gallons. Did I use too much?

Ian

if you got that much less final volume it tells me you lost some sparge water in the system. ie did you have your normal volume of sparging water? at 7g of fluid i'd think your leaving sugars in the bed most 5g batches i do have about 8g for a gravity around 55-60

Why are you step mashing a simple grain bill of two row?

I've been experiencing a drop in efficiency also and I'm positive it has to do with the winter temps. I've been losing heat like crazy in between batch sparge infusions.

Yep, it sounds to me like you might have used less sparge water than you thought. Or perhaps you had some wort loss in your system, which would also depress your brewhouse efficiency.

Did you carefully check your pre-boil volume to know if you under-sparged/had a loss of wort in your system?

About 1 year ago, I got a substantial drop in efficiency over 2 brews and for no obvious reason. After the second brew, I checked the thermometer and found that it was way off. Replaced the battery, and everything went back to normal.

-a.

When I had a big drop in efficiency, it turned out to be te LHBS bought a new mill and it wasn't crushing quite as fine.

Linc

eriktlupus said:

if you got that much less final volume it tells me you lost some sparge water in the system. ie did you have your normal volume of sparging water? at 7g of fluid i'd think your leaving sugars in the bed most 5g batches i do have about 8g for a gravity around 55-60

Click to expand...

It was the sparge - I did sparge out at 168 on previous batches, and now that I check my notes - I don't think I did - I bet that wast it. Thanks!

So to "why step mash" - well to answer that, I have found I can get much better mash control with a step mash. By changing the times mashing at 140F and 158F I can get a dry or malty beer. 30min at each temperature is a good start, but by going to 40 min at 140F and then 20 min at 158F I get a dryer low gravity beer and by swapping those times, I get a maltier beer. Also, I have more leeway at the temperatures. If I single step mash at 150F, I am right at the boundary of the dry and sweet enzymes, so if I'm out by only a few degrees, I get inconsistent beer, but if I step mash, I have quite a bit of leeway for each of the alpha and beta amylases.

It works for me - I've always done it that way and my beer is better than most I know, so I'm reluctant to change.

Ian