I messed around a bunch this past winter on my lagers doing step mashes that included a post saccharification rest at 158 F to get some more limit dextrins to improve mouthfeel. I think I was fairly succesful, except in one batch were I got distracted and held the Sacch. rest too long so I think the wort was too converted by the time I took it to 158 F so the final step did nothing. So now I want to use my refractometer to monitor conversion so I can improve on my technique to get more consistent results.
Many people do an Iodine test for full conversion, I'd like to use my refractometer to do that - and then some. Basically I want to be able to whip out my refractometer and check the gravity so I can do my temp. step up at say 85% percent conversion. I'm talking mash efficiency, not brewhouse efficiency. I'm assuming I can get to "full" conversion (100%) - that is based on the numbers given in the malt analysis. Typically I see 80% conversion as a pretty common value as determined by the malster. This is then used to determine the SG potential of the grains, for example, pale malt at 1.039 gravity points per pound per gallon (100% is really 80%, if 100% = 100% the the PPG would be even higher)
I want to talk out loud here to make sure I've got things right. Palmer's book didn't quite spell it out enough. So in my mash, say I have 6 lbs in 3 gals (for math ease) what should by SG be at full conversion? (before sparging). Simple math would say 1.068 (2 X 1.039), but that doesn't account for water absorbed by the grain. If water is absorbed by the grain at ~ 1.25 qts/lb, that would be 1.2 gal. lost to absorption. If we exclude this, then the SG at full conversion would be 1.130!!! which seems way to high. So I'm thinking I should include all or most of the strike water in the calculation as even though it is "absorbed" by the grain it is still available to the rest of the wort as far as gravity is concerned.
Does anyone have a better figure for water absorption to use (for this purpose) or have any other recommendations?
I've got ProMash but I don't see a calculator to use to address this question. It is possible I've overlooked it, or there is some trick I'm unaware of.
I could take readings every 5 min. starting at time zero, and then after a few data points I could with some refreshing of my memory on enzyme kinetics I could calculate when to do my temp. step. I really don't want to have to open up and stir my mash every 5 min. to get a uniform sample. Then of course every grain bill is different so I'd have to repeat this each time I do a different recipe, and then accounting for older grain, yada, yada, yada.
Many people do an Iodine test for full conversion, I'd like to use my refractometer to do that - and then some. Basically I want to be able to whip out my refractometer and check the gravity so I can do my temp. step up at say 85% percent conversion. I'm talking mash efficiency, not brewhouse efficiency. I'm assuming I can get to "full" conversion (100%) - that is based on the numbers given in the malt analysis. Typically I see 80% conversion as a pretty common value as determined by the malster. This is then used to determine the SG potential of the grains, for example, pale malt at 1.039 gravity points per pound per gallon (100% is really 80%, if 100% = 100% the the PPG would be even higher)
I want to talk out loud here to make sure I've got things right. Palmer's book didn't quite spell it out enough. So in my mash, say I have 6 lbs in 3 gals (for math ease) what should by SG be at full conversion? (before sparging). Simple math would say 1.068 (2 X 1.039), but that doesn't account for water absorbed by the grain. If water is absorbed by the grain at ~ 1.25 qts/lb, that would be 1.2 gal. lost to absorption. If we exclude this, then the SG at full conversion would be 1.130!!! which seems way to high. So I'm thinking I should include all or most of the strike water in the calculation as even though it is "absorbed" by the grain it is still available to the rest of the wort as far as gravity is concerned.
Does anyone have a better figure for water absorption to use (for this purpose) or have any other recommendations?
I've got ProMash but I don't see a calculator to use to address this question. It is possible I've overlooked it, or there is some trick I'm unaware of.
I could take readings every 5 min. starting at time zero, and then after a few data points I could with some refreshing of my memory on enzyme kinetics I could calculate when to do my temp. step. I really don't want to have to open up and stir my mash every 5 min. to get a uniform sample. Then of course every grain bill is different so I'd have to repeat this each time I do a different recipe, and then accounting for older grain, yada, yada, yada.