Friday, October 13, 2017
Persistent Coffee Myths #142: Uniform Particle Size of Grind is Good
We had a customer walk in today who told us he read an interesting article about how you could achieve a more consistent particle size when grinding your beans if you freeze the beans first... Okay, where do we start?
First of all, please... never put coffee in the freezer. The foil and plastic bags get brittle at that temperature and allow the coffee to soak up odors from the freezer. What do you have sitting next to that coffee? Fish, garlic spinach... whatever it is, that's what your next cup of coffee will taste like. Coffee is one of nature's most efficient odor-absorbing substances, which is why they use spent coffee grinds to clean the floors in fish rendering plants. Yes, eeeeew. Also, freezers are not cold enough to stop the normal oxidation process, so it doesn't even help to keep your coffee fresh.
Somewhere at some time, some burr grinder manufacturer popularized the notion that burr grinders make uniform particles when they grind, and that uniform particles are for some reason optimum when brewing. There are two points to this, and both are wrong.
1. Burr grinders do not make uniform particle size. They do make a MORE uniform overall size than small countertop types, but not by much. I enjoy grinding some beans in our $900 Bunn burr grinder and showing it to customers along with some I ground in a $15 small blade grinder. They can readily see tons of "fines" in both samples. It is a comment on human nature that somebody makes this claim, and everybody copies and pastes and re-blogs it, but they never actually look at samples from both grinder types to see if it's true. It's simply not true.
2. Uniform particle sizes do not improve an average brewing. If you are lucky, it might improve the occasional brewing. This is simple math: Coffee grinds have a "sweet spot" for brew time. In a Press, that sweet spot is maybe 20 seconds, and is affected by the humidity that day, the temperature of your water, whether you stir it or not, etc. Since this sweet spot is very hard to hit on the button, except for odd people who want to watch all these variables and use a thermometer and stop watch, we might want to consider the math of non-uniform particle sizes.
The average person just adds hot water to a press or drip machine or pourover and does not have total control over these variables. That means they are more than likely missing that "sweet spot" most of the time. Now, if you have a 50% variance in particle size, your "sweet spot" gets broadened considerably. Yes, a few particles overbrew, and some underbrew, but here is the final funny thing: That's good. Because any time you are getting exact extraction from one particle size you are not getting as wide a range of elements in your brew as you would otherwise. The positives outweigh the negatives.
Summary: You will hit a "sweet spot" much more often with non-uniform particle size, and you will get a fuller range of tones extracted from the beans. As often, the simplest methods and the cheapest machines are fine for everyday use and enjoyment.