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Mash Efficiency with Sugar Addition


Jun 13, 2011
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The other day I was making a Sweet Stout. I put in my measured pre-boil volume and measured pre-boil gravity and got a really low mash efficiency. The estimated mash efficiency is 63% and the measured mash efficiency is 70%. My mash efficiency is usually 78%.

Even though I'm adding the sugar at the end of the boil, BeerSmith appears to be taking the lactose into account when estimating what my pre-boil gravity should be. In order to get an accurate reading of my mash efficiency, I have to reduce my sugar addition to 0, go back to the mash screen and read the new 'measured mash efficiency' and jot it down somewhere because as soon as I increase my lactose back up to a non-zero amount the measured efficiency will be wrong again.

BeerSmith 1 had this same problem when adding sugar or doing a partial mash. I haven't checked if BeerSmith 2 has this problem when doing a partial mash, but it definitely does when adding sugar.