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Beersmith mash efficiency question

Greetings and thanks for your patience on this one,

I did my first all grain batch recently (a Saison recipe from “Brewing Classic Styles”) and got an OG of 1.60 using a 10 gallon Igloo cooler with a 10" false bottom and did batch sparging – thanks to Denny’s “pragmatic” perspective on sparging. I actually got a higher mash efficiency than I’d predicted (I had hoped for 65%), so I left out the one pound of sugar the recipe called for since I had reached the recipe’s OG without it. (Due to the high proportion of Pilsner malt, I did a 90 minute mash and boil).

Based on calculations of the recipe, a 100% efficient mash would have given 479 gravity points and with an OG of 1.060 in 5.5 gallons, I got 330. Assuming a quart of wort left behind in the mash tun (what the supply store told me), I got 345 total gravity points in 5.75 gallons, so the mash efficiency would therefore be 345/479, or 72%, correct? The brewhouse efficiency would then be 330/479, or 69%, if I’m doing the calculations correctly.

When I plug in 69% brewhouse efficiency (BeerSmith calls it total efficiency), I get an estimated mash efficiency of 78.4%, but that doesn’t jibe with my calculation of 72%.

So, my questions are;

  1. Why is there a disparity in mash efficiency?
  2. Is there any way to plug in mash efficiency to BeerSmith rather than having to use total efficiency (I wonder why BeerSmith does it that way – it seems counterintuitive to me)?
  3. Am I making some fundamental mistake that results in the mash efficiency disparity above?

Overall, the experience of doing an all grain batch was a LOT of fun and I’m glad to leave my partial mash approach behind. However, I’m very aware that I have much more to learn and any insights you can give me would be greatly appreciated. I think I’ve got the bases covered after mashing – I do starter cultures, full volume boils, treat the water with Camden tablets, chill the wort within 15 minutes, oxygenate, and control fermentation temperature with a fermwrap and digital heat controller.

Thanks to the NB Mpls store staff who answered my endless questions prior to brewing this batch!

Beersmith is making a number of assumptions about volume loss at each post-mash step. It may be assuming volume loss in the tun and/or volume loss in transfer to the fermenter and/or volume loss to trub in the fermenter.

If their estimates don’t match yours, then I’d adjust their volume variables and see how their calculation compares to yours.

Cheers.

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