Missed OG by a lot!!

[deeve007]

Hey guys,

So my current brew, with a target OG of 1.077, I hit 1.060 only. My previous brew I hit both OG and volume on the nose, so it seems like it's not something I'm doing that's down to my general process (though obviously I will review that too just to do all I can).

A solo commercial brewer friend of mine says he also has trouble with high ABV beers, and he does it for a living (I can't speak for how good his overall processes are though, just another point of reference for me).

Any suggestions apart from the main ones I can find via google? (which I was aware of when first starting out when I got a super low OG, but addressed that for normal ABV beers it seems).

And adding corn sugar for this batch to address it in the short term, I've read the best time is after high-krausen rather than at start of fermenting, is that right? And a pound of sugar will add around 10 points to gravity?

Cheers guys.

 

[EnglishAndy]

My rule of thumb is to knock 10% off my efficiency expectations and run my recipe through the spreadsheet that @doug293cz wrote to see if my sparge is big enough.

 

[deeve007]

One thing I am noticing, when I remove my grain after the mash, the water volume in my pot is around 50% even after allowing to drain for a while... I let drain for about 5 minutes then begin to sparge. Is this normal for most brewers, or should I be getting more wort left after mashing and draining?
(though as I wrote, last few batches I hit OG and volume about right, so if this was the issue then why only this time and not previously??)

 

[doug293cz]

The bigger the beer, the lower the lauter efficiency, all else being equal. The chart below shows this effect:

A traditional mash tun will have about 0.12 gal/lb grain absorption rate, and a BIAB with a good squeeze will put you around 0.06 gal/lb. BIAB with no squeeze will get you in the 0.08 - 0.10 range, depending on how long you drain. Chart assumes both initial drain, and all sparge drains have the same grain absorption rate. Getting low absorption rate on initial drain is most effective for increasing efficiency.

Mash efficiency is equal to conversion efficiency times lauter efficiency, so to know where your issues my lie, you need to measure both. Conversion efficiency target should be above 95%, and lauter efficiency target as per chart above.

Measure your conversion efficiency using the method here. Biggest contributor to conversion efficiency is grain crush, and second most important is mash time. Calculate your lauter efficiency from:

Lauter Efficiency = Mash Efficiency / Conversion Efficiency​

Brewing software will give you mash efficiency based on your grain bill, pre-boil volume and pre-boil SG, or from grain bill, post-boil volume and post-boil SG (if no sugar/extract added during boil.)

The spreadsheet mentioned by @EnglishAndy can be found here.

Brew on