The importance of grind
While I am familiar with the five main factors that affect extraction (time, temperature, turbulence, grind, ratio), I will admit that I’ve thought of them all as having somewhat equal influence. I can’t say I’ve really stacked them up against each other, but all have been up for grabs when I’m dialing in a brew recipe. However, today changes that perspective.
Bunn recently lent us a trifecta to play with. Naturally, I was excited as I’ve heard a lot about it but have only gotten to taste a few brews from it. The core concept behind the trifecta is that every variable is programable and controllable. Over the week that we’ve had the machine, I’ve tried a variety of suggested recipes found on the trifecta website. Most brew ratios were pretty atrocious, using 28g of coffee for a 340ml brew volume. Aside from some ineffective pre-wetting and tedious cleaning, the trifecta worked well, even if the recipes weren’t great.
Today, we tried to dial in our own recipe, to come up with something that was tasty. Andy Schecter was kind enough to come over and let me use his extract mojo. We started with the machine’s factor settings and went from there. Initially, yields were all too low, coming in between 16.8% to 17.9%. Despite changing a variety of variables, the extraction percentage would hardly move. However, after several brews we decided to change the grind. Initially I had hesitated to tighten the grind as muddiness was an issue in some of the cups. Two notches finer, and the percentage went from, 17.9% to 20.5%. A very significant jump.
This got me thinking, if grind is so important, how sure am I that all our grinders are calibrated the same? How are people grinding at home, and how can we better communicate how they address grind particle size? Grind sizers such as this one may be a good solution.
The experiment has raised a few more questions for me. If these variables don’t influence the extraction yield significantly, but do largely influence flavor, what’s occurring from a chemical standpoint? Am I extracting different solubles?
If anyone knows of any solid reading on this material, I’d appreciate it. But for now, grind particle size has a new found place of respect in my life.
Hey, are you guys going to be at NERBC this year? If so, I would love for you to bring some of your coffees to brew on the trifectas. We will be there supporting the Brewers Cup competition.
In our experience you can do several things to affect both flavors and extraction percentage without adjusting grind size or dose weight. We have found that manipulating preinfusion time and % as well as various changes in turbulence can effect changes in extraction. During your experiment what variables were you changing (aside from grind) to try and increase extraction %? Also, were you able to filter your brews through a paper filter prior to taking a TDS reading?
Looking forward to possibly seeing you soon!