I have been designing beers using math since I first learned how to calculate a brew 25 years ago. There is something rewarding in the formality that goes into crunching numbers and coming up with the recipe on paper that is used as the brewing road map for wort production and the all-important start to something [hopefully] wonderful to follow. If a mathematical brewer is handed a recipe, the first thing they will likely do prior to brewing is to check the math and adjust the recipe for their system. That’s just how some brewers are wired. But beyond the basics of correcting for brewhouse efficiency and anything one actually knows about their hop utilization no real magic comes from this exercise.
Hand me a recipe for a batch of a given size, ask me to scale it to another size and the most direct method is to simply scale the recipe proportionally by volume. The recipe is a road map and leads us in a general direction. Brewing great beer requires much more than a recipe and the greatness usually comes from tweaking a brew with repetition.
It’s been a while since I have taken a musical digression and this is a pretty good topic to lead me down my favorite rabbit hole. My musical life is lived vicariously through talking to musicians and my friend Brandon allows me to stay connected to my favorite jazz instrument, the saxophone. Brandon plays an early ‘60s Selmer Mark VI tenor named Bessie. Her lacquer is worn thin and she sports a gorgeous patina associated with age and dignity. Bessie is the type of tenor that young tenors look forward to becoming after years of being played by great musicians. These days Bessie is played with an Otto Link mouthpiece and medium hard reeds, the same set-up used by greats like John Coltrane and Dexter Gordon. Brandon is a great tenor player and has his own sound and techniques to produce his sound. Yeah, his tenor rig is the same basic set-up used by many great jazz tenor players but the instrument is just a piece in the sound puzzle. When a musician reads music and plays the tune they are reading, the tune is going to sound different when played by another musician using the same or similar instrument.
Very few brewers, whether homebrewers or pro brewers, have the same brewhouse and will likely produce different beers from the same recipe. The reasons for this are entirely different from my musical parallel. Most brewing recipes provide a general guideline of malts, hops, brewing water, yeast, mash method, boil time, fermentation temperature, clarification method, aging duration, and packaging specifics. It’s hard enough for brewers to brew the same beer time after time using the same equipment and actually knowing the specifics of ingredients and process. Two brewers using different equipment to produce the same beer is very difficult, and two brewers using different equipment and different ingredients to produce the same beer is virtually impossible. The batch size really pales in comparison when put into the context of all of these variables.
A brewing recipe is a road map. If you are proficient in brewing calculations, which by no means is a requirement to brew really good beer, the things that you can do to reconcile a recipe is confirm that the malt bill is going to give you the wort OG (original gravity) specified by the recipe. Wort gravity is a major driver of flavor and body and it really helps to nail your target OG. Checking the bittering calculations is also helpful, but in my opinion calculated bitterness tells me very little about how bitterness will be perceived in a beer. And the truth is that very few homebrewers and small commercial brewers know anything at all about their hop utilization rates, meaning that most hop calculations and published IBUs are fancy approximations.
Use that recipe as a road map, evaluate the finished beer, make adjustments and keep brewing until you come upon the right beer. I truly believe this is the art of brewing. Tweaking the recipe includes playing with different malts, using different hop varieties and hopping rates, playing with the water chemistry, and pushing the fermentation in different directions. After a recipe is used for the first time and tweaks to the recipe are made, the recipe is now yours. Happy brewing!