When calculating efficiency what post boil volume measurement should I be using? Should I include the total volume of wort plus trub and hops or estimate volume of trub and hops and subtract from total volume. I realize it’s a small variation and may only affect the efficiency calculations by 1% or so but just curious as I start to dabble into some hoppier beers for a change.
That depends on what you care to know. Both statistics are used. Professionals especially like to know efficiency based on the volume that actually makes it into the fermentor, often called brewhouse efficiency; this tells them how much grain (money) gets them how much product. But I find this irrelevant, and the volume into the fermentor depends on how much hops I used, how carefully I racked, and so on. I personally only ever look at the efficiency based on the total volume in the kettle after the boil, sometimes called mash efficiency. This is a more of a constant, and can tell me what I might want to know about my ingredients and process. And the volume of liquid hops and trub displace, and the volume they absorb, offset each other so closely I ignore them. I just measure the volume in the kettle with a dipstick I made. First thing I do when I get a new kettle is make a dipstick.
Measured as chilled, right?
Yes.
Thanks, makes sense
Actually, not to contradict Robert, but the mash efficiency is measured before the boil, not after. The Specific Gravity and pre-boil volume are used in the calculation. The point is to extract as much sugar from the mash as possible and to know that, the Specific pre-boil Gravity and pre-boil volume are used. So, if the pH was off, or there was some channeling, or the liquor temperature was off, or _______ fill in the blank, the mash efficiency will suffer.
Yeah, I agree with you. I consider mash efficiency to be what you get before boiling
There are so many different systems of naming these things, I get confused. Textbooks vs Kai vs Beersmith etc. etc. all seem different. So maybe I’ve made up my own category! But it’s what tells me something. I know that the post boil gravity won’t be simply preboil multiplied by the reduction in volume, because if you’re doing it right, you precipitate a measurable amount of extract in the trub, and add some from hops. And more important, I don’t/ can’t accurately measure preboil volume of the hot wort. So the best true measurements I have are post boil in the kettle, and that seems to me the best guide to what I managed to get out of my ingredients. It takes into account my whole process, including mashing and boiling. So I guess I’m still saying, measure what you care about. Where it gets tricky is understanding what other people mean by a term, since there doesn’t seem to be a single standard agreed on. Now I know what some of you guys mean at least. And it makes much more sense to call it “mash efficiency” coming straight out of the mash. Anybody know a common term for what I measure?
I never took the meaning of either the OP’s question or Roberts reply to be about mash efficiency. As soon as the OP mentioned post boil and began including volumes it immediately became about brewhouse efficiency, not mash efficiency. Robert responded accordingly.
I agree, Kevin, the OP was asking about BrewHouse Efficiency, not Mash Efficiency. However, in Roberts post, he stated: “…the total volume in the kettle after the boil, sometimes called mash efficiency.” and I didn’t want the OP to get confused with the terms as these terms are measurements made at two completely different stages of the brewing process that tell us two completely different accomplishments. Suffice is to say, these are the definitions, practices, principles and disciplines I learned to use when I brew.
FWIW, I do measure kettle full gravity to determine mash efficiency bit do calculations rather than relying on things like Beer Smith to do it for me (Beer Smith tells me my measured mash efficiency is always greater than 100%, which is impossible and I haven’t yet figured out the right configuration to reflect what the actual numbers are). I simply take the predicted OG, multuply it by the desired end of boil volume, and divide that number by the pre-boil volume.
From experience I know there are some errors from what my refractometer sees and if I am about 3-BX or so higher (yes I convert that number to degrees Plato) than what Beer Smith predicts, I know I am OK. If not, I can compensate with a longer boil or some DME. I also monitor the kettle gravity during the boil to make sure things are OK.
This method normally brings my OG within about 2% of the desired value and correlates to a brew house efficiency of 80%.
Obviously, YMMV.
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And individually, it doesn’t matter what we measure or what we call it as long as we’re consistent. I expect most of us are just measuring this in an effort to have consistency and predictability in our own systems – to know what we can regularly expect to get, so we can use this to formulate and adjust recipes. “I always get X gallons (at whatever stage of the game) at Y gravity from Z malt, so this is how much malt I’ll need next weekend…”
Exactly. I use Beersmith’s efficiency calculator as a “beer into the fermenter” measurement and adjust it for inconsistencies in gravity and volume.
That’s what I use as well. As long as the same measure method is used from brew to brew, good decisions can be made for future brews.
I measure my strike water cold, though, so I don’t need to account for the 4%(?) or so correction. If you had a hot liquor tank and measured mash water after it was already heated, you’d have to adjust efficiency for that.
Right, I also measure strike and sparge water cold, and chilled wort. So without bothering to measure volumes at intermediate points while hot, and then trying to make corrections for the expansion at different temperatures,* I know exactly what went in and what came out.
*4% is only at or near boiling, and at boiling, bubbles further complicate things; and expansion isn’t linear leading up to that point. Anywhere from just above freezing to lukewarm it’s not worth considering.