Fines are a fact of nature when it comes to coffee brewing. Coffee beans have unpredictable breakage during the grinding process and will always produce particles that range in size – with some that are much smaller than the rest. These relatively smaller coffee particles will compete with the majority of your other coffee particles for water solubility. This competition can explain why a brew will always be limited, or at least defined, by the relative fines in the coffee.
This overall concept was first introduced to me by David Walsh (of Marco and The Other Black Suff) back in 2009. I’d be lying if I didn’t acknowledge that a friend and colleague, David LaMont, also pointed out the importance of fines around this time but it was Mr.Walsh that really got me thinking about it during a presentation at La Marzocco’s Out of the Box event in Berkley. The gist of his talk centered around a brew he prepared, asking the audience how we liked it – most did. He then revealed that this brew was measured at 26% extraction (or something high like that). David implied that most of us like this coffee because he had sifted out “fines” and used a relatively homogeneously sized batch of ground coffee. This could mean that the proverbial consumer pronoun “we” don’t necessarily dislike coffee extracted past 22%, but actually don’t like coffees extracted over 22% when that coffee includes fines.In theory, these finer particles would deliver a slightly higher extraction that would mix with less extracted brew from larger particles to deliver a yield of beverage that was deemed tasty.
This really gets into the unknown realm of what is exactly happening at each moment of increasing extraction. Are there predictable flavors at various moments – other than grassy under developed and bitter over extracted? Is there benefit to a non-homogeneous grind size profile – remember when every one touted a “bi-nodal” espresso profile’s superiority to a uniform grind size?
All of these questions keep coming back to me as so many competing brewers are implementing grind sieving strategies…and winning. I’m also reminded of this as experimentation continues into coffee consumer preference, much of which is being pursued by Walsh, Paul Stack (also of Marco) and a handful of others.
So a question that comes to mind is: Is it sustainable to pursue a coffee grind that is more precisely uniform than today’s commercial grinders offer? I mean, if a grinder could produce a more concise grind profile it would exist, right? (hint, hint grinder manufacturers). If not, does that mean one is expected to waste the coffee that ends up sieved out? By some modest calculations one could be looking at discarding up to 20% of their coffee, depending on their spread preferences and grinder used. In a climate where coffee prices are rising and the availability of good coffee is becoming a more cherished luxury does it make sense to embrace a procedure that requires so much waste? Or will coffee fines one day become like bread ends, often unloved and discarded? Does anyone have any good recipes for leftover coffee fines?