Moisture impacts on PPG for grains

[catalanotte]

I have reviewed most of what is available from articles and books on calculating PPG from malt quality reports and see one inconsistency on how this typically done. Not all sources reduce the PPG to account for moisture, and appear to be on a dry basis. I am also curious how others look at coarse vs fine Extract, and adjust. Seems liek the standard is use coarse as a better approximation of milling, but if a coarse-fine difference is not given, what do people use to reduce the fine extract d.b.?

For example, I have a Munich (5L) sheet from Bestmaltz:
Moisture - 3.7%
Extract (Fine Grind) dry basis - 81%
Fine-Coarse Difference - .5%
EBC - 15 (6L)

I am estimating PPG as:
Extract (Fine) minus Fine-Coarse Difference (81%-.5%=80.5%)
Extract (adjusted to Coarse) * (1-moisture %) (.805 * (1-.037))= .775
77.5% of sucrose potential (46 ppg) = (.775 * 46) = 35.6 PPG

Same calculation, but not adjusting for moisture results in a PPG of ~37. This seems consistent with many sources for Munich which range from 35 to 37. Not a huge difference, but I have seen a number of malts with moistures as high as 7-8% and a fie-coarse difference of 4% which become a big impact. It seems like this PPG reduction for moisture is appropriate since we are typically batching recipes by weight that includes the moisture.

Any errors in my approach, and what has produced the most consistent results for others?

 

[3 Dawg Night]

I think the reason most brewers (myself included) don't adjust for moisture is that we don't want to do the math. As long as you are consistent in your process/calculations from batch to batch, it will all come out in the wash. For the average brewer, if gravity is consistently a bit low, they'll just add some extra base malt to compensate.

I know that doesn't really address your specific technical question, but it does address the question of "why don't we adjust to compensate for moisture?"

 

[catalanotte]

I think the reason most brewers (myself included) don't adjust for moisture is that we don't want to do the math. As long as you are consistent in your process/calculations from batch to batch, it will all come out in the wash. For the average brewer, if gravity is consistently a bit low, they'll just add some extra base malt to compensate.

I know that doesn't really address your specific technical question, but it does address the question of "why don't we adjust to compensate for moisture?"

Thanks, totally agree that this as another variable that we typically roll up in the efficiency percentage. If relatively consistent, it doesn't make much of a difference, i.e. you're getting 75% of "wet" weight or 79% of "dry" weight, both give you the target gravity.

I was looking at this more to separate things I can control in the mash/sparge process, from those I can't, like extract potential that really isn't there by "wet" weight. When I used these adjusted PPGs across a couple of batches that used varying types of malt, the resulting conversion efficiency and overall brew house efficiency spread came down considerably. Probably more effort than its worth for most, but I am trying to get more dialed in with my target OG. Have been at +/- 2-3 pts at target volume, trying to get better so I am not adding water or extending boils.

Engineers curse, always running numbers looking for answers.......