Well its finally happened to me, I missed my OG. I thought this would happen when I was new to brewing, but no it happens after however many batches. I've been trying to identify where I must have gone wrong and just can't figure. perhaps i'm too close to the issue so I thought i'd post it here and see if there were any ideas. first the grain bill. (BN recently did an interview with Kern river so I jotted down the Citra recipe and translated it to a 5 gal. batch) 11lbs 2 row 8 oz. Munich 8 oz. Crystal 10 8 oz. Cara-pils 4 oz. White Wheat 4 oz. Honey Malt I have the LHBS mill all my grains. Mash in: 16.25 qt. @ 161.8F to reach 148F (I hit 149 and forgot I was looking for 148, but whatever) I batch sparge; 4.5 gal. @168F Collected 7 gal. of wort @ 1.045 (Est. 1.062) - didn't extract enough? Boiled down to 5 gal. Target OG: 1.055 (Est. 1.071) Here are my thoughts 1) Measurement error: Typically I take my OG measurement once the wort is cooled, but before the yeast is pitched. Saturday was hot as hell and cooling was taking forever so I took the measurement when the beer was ~115. I use a refractometer that was calibrated in the morning There is an argument against this, as I brewed two beers this day and the first one hit all numbers spot on. 2) Mash problem: Seems the most likely, however I will state that I am always below Beersmiths pre-boil gravity number, but have never missed the post-boil. My efficiency is between 70-74%, so for this beer I'm coming in around 58%??? This was a really basic mash and I didn't change any of my process so I just can't understand why I missed my OG by so much. Any thoughts?
How long did you mash for? Did you do a conversion test? I've found with lower temp mashes I need to go a bit longer for full conversion. I can't quote anything to back it up...just my own experience. I buy my 2-row in 50lb sacks and I've also noticed a lower yield from the bag I'm on now compared to previous ones. That might contribute to your problem.
60 min. mash (this is my typical length/temp for IPAs) No conversion test I did consider the grain portion. I am starting to wonder if thats it.
Perhaps the mill setting on the LHBS mill as changed? Crush can make a big difference. My efficiency with crushes from Northern Brewer is at least 5% greater than when I purchase crushed grains at Midwest Supplies. Did you look at the crush before you brewed? Also, if you taste your grain at the end of a mash, you can get a sense for whether you are leaving behind a lot of residual sugar. If your grains do not taste sweet when you chew them, you have converted the starches and extracted the sugars; you can rule out conversion and extraction issues. This could point to measurement errors, which could be volume (you oversparged and diluted your beer), mass (too little base malt was weighed out, or perhaps it had a high moisture content at the time of weighing), or refractometer usage. I always check at my OG refractometer measurement against a hydrometer. It's probably a good practice. (And you can ceremoniously drink the sample afterwards to great fanfare as you celebrate the end of the brew day and prepare to start drinking the batch you made the previous month.) Final advice -- keep some DME on hand just in case, and then you can compensate for this type of problem.
As mentioned before it could have been the crush. Did you stir enough when you added the sparge water? Could your thermometer have broken and is no longer accurate so your mashing temps were off (high or low?)
Definitely partially a measurement problem. 7 gallons x 45 gravity points per gallon = 315 gravity points / 5 (gallons) = 63 gravity points per gallon. So, 7 gallons of 1.045 wort boiled to 5 gallons should be 1.063. Unless the volumes or gravity readings are off... I think that is right.
I used up the last of my DME on the starter and really didn't think much of it since I'd never missed an OG before. Definitely leaning towards grain volume, or unextracted sugars. I didn't taste the grains afterwards but I did taste the wort as it was nearing the end and I could detect very little sugar to it. Verifying the thermometer is a good idea, I haven't done that in a while so I should. Refractometer should be good, but I will give it a double check as well. I also think the measurement could be a portion of it and I just wonder if the temps could have something to do with it. Consider I calibrated the refractometer inside (~75 degrees), then I brewed outside and took the measurement 2-3 hours later. Outside temps were 105+.
Just an update- I talked with the LHBS who was able to rule out crush/grain quality as they brewed after I picked up my order and they did not have any problems. Of course measurement (weight) could have been off, but thats impossible to verify retroactively. They did give me an idea I basically skimmed over and that is sparge. I had two batches going on Saturday and I bet I didn't get my sparge right even though I went through the same process. I was just moving quickly between beers and trying to keep everything moving....I bet thats where I messed up. Not the end of the world since its just a lower ABV beer but it is good to have an idea so I can correct it in the future.
was your OG measured at 115, did you say? That will make a difference to the measurment, as that is calibrated to around 65 degrees (or thereabouts) I have written in my brew book, and found in Papazian, what the conversion is. i don't recall offhand what it is, but it's at least a couple points per 10 degrees over / under.
I don't think he said that (he said it was 105F outside and that he had calibrated his refractometer inside where it was 75F), but FWIW a 1.045 gravity reading at 115F on a 60F calibrated hydrometer would equal a 1.054 gravity reading.
if you over-sparge but then hit your intended volume, wouldn't it not make a difference since the same amount of sugars are still there?
