PPG calculation of pre-loaded malts

[Garrett Meldrum]

Hello, I am doing some research and attempting to calculate the entire brew process myself as an exercise for understanding brewing calculations. When I am starting from the grain sheet going up, my calculation for specific malting companies PPG (after converting from the Fine Grain Dry Basis) is returning different values than what Brewer's Friend shows.

Why is this? Not only the PPG value (which is the biggest priority to me) but additionally my color value calculations are entirely different than the ones presented by Brewers Friend. For Example:

Brewers Friend -- CRISP - Extra Pale Marris Otter - Lovibond: 2L - PPG: 37.5
Hand Calculations -- CRISP - Extra Pale Marris Otter - Lovibond 1.7L - PPG 37.076

My calculations are derived from John Palmer's How to Brew. Any insight into this issue is much appreciated, thank you!!!

 

[Mont Y. Märzen]

I don't know off hand what formula BF is using for PPG and color, but check the 'help' section on the recipe editor. I seem to recall that the various formulas used there (as well as in other stand alone calculators) are all disclosed and documented.

To this specific issue of PPG though (and perhaps color as well), we are dealing with an agricultural product that has natural variability crop season to season and batch to batch within a season as the entire crop isn't malted and kilned in one go. There will always be slight variation. Malt houses usually post a spec sheet with an average or target for a particular malt. If you need the exact specs for a batch, those are sometimes available, but usually only to large volume purchasers.

But as a homebrewer, fret not. You can determine your own Fine Grain & PPG via a Congress Mash, or a rough approximation to it. You can find the instructions here on BF. That might be useful to you if you purchase by the sack. I've done a few, but honestly, the pre-loaded figures are so close, the variance became either negligible, or even unmeasurable at my scale of 5gal batches. The one exception was when a malt wasn't in the database and there was no good approximation. (Breiss Dark Munich 30L, which apparently, no longer is in production)

As for color variance, 0.3°L off isn't even perceptible to humans. (I'm guessing, certainly, I know I couldn't tell) You'd have to be *really* well trained to look at any two random beers and say, "Beer-1 is 2-SRM, Beer-2 is 3-SRM" not to even speak of numbers beyond the decimal, and anything past 25–30 also isn't perceptible in almost any glass you pour it in, with 40+ being merely an academic curiosity. (which if you learn how the color of beer is measured, you'll learn the size, and shape, of the container, absolutely matters—the official reference, I believe, is a 1cm cube which no one drinks out of and the light used to shine through it is in the deep if not ultraviolet range, but no common beer drinker owns such a light bulb.)

 

[Donoroto]

Hello, I am doing some research and attempting to calculate the entire brew process myself as an exercise for understanding brewing calculations. When I am starting from the grain sheet going up, my calculation for specific malting companies PPG (after converting from the Fine Grain Dry Basis) is returning different values than what Brewer's Friend shows.

Why is this? Not only the PPG value (which is the biggest priority to me) but additionally my color value calculations are entirely different than the ones presented by Brewers Friend. For Example:

Brewers Friend -- CRISP - Extra Pale Marris Otter - Lovibond: 2L - PPG: 37.5
Hand Calculations -- CRISP - Extra Pale Marris Otter - Lovibond 1.7L - PPG 37.076

My calculations are derived from John Palmer's How to Brew. Any insight into this issue is much appreciated, thank you!!!

I speculate that the values Brewer’s Friend uses are from previous crops. As you might imagine, the PPG of a grain varies from season to season and even from farm field to farm field.

I understand your desire to end up with the highest accuracy in your calculations; to check your steps and compare them to the calculator, use the BF numbers. To calculate what your batch will be, use the manufacturer’s numbers.

That all being said, the practical differences in the results will be indiscernible from process error. That is, differences in your process from batch to batch will have a much greater effect than using one set of numbers or the other for calculations.

Hope that helps.