Brewing standards, extraction science and espresso hardware analysis for serious home baristas. Every piece labelled with how its claims are known.https://beansandbarista.com/en-ushttps://beansandbarista.com/blog/espresso-channeling/https://beansandbarista.com/blog/espresso-channeling/Every guide treats channeling as a fault you either have or you don't, caused by grind, distribution or tamp. The published physics says something stranger: uneven flow between pathways is always present, it feeds on itself, and for most of a shot it hides behind an average that looks fine. Here is the causal chain, from the first 6.7 seconds of wetting to what the spent puck looks like under an x-ray.Fri, 11 Sep 2026 00:00:00 GMThttps://beansandbarista.com/blog/espresso-puck-prep/https://beansandbarista.com/blog/espresso-puck-prep/The espresso world sells three puck prep tools and has run a controlled trial on one of them — which lost. The peer-reviewed literature says the tamp exists to level the bed, not to compress it, and the arithmetic says why: the pump presses the puck about twelve to twenty-four times harder than your hand can. Here is what has actually been measured, including the study that made a puck deliberately uneven and got a more stable shot.Fri, 11 Sep 2026 00:00:00 GMThttps://beansandbarista.com/blog/why-is-my-espresso-puck-wet/https://beansandbarista.com/blog/why-is-my-espresso-puck-wet/Every page on this search tells you a wet puck means your grind or your tamp is wrong. A measurement nobody cites says otherwise: on a commercial machine at a verified 9 bar, a 20 g puck holds 20.85 grams of water — and that figure did not move when the burrs went from new to worn out. Here is what is actually in the basket, what removes it, and what the removal costs.Fri, 11 Sep 2026 00:00:00 GMThttps://beansandbarista.com/blog/why-is-my-espresso-sour-or-bitter/https://beansandbarista.com/blog/why-is-my-espresso-sour-or-bitter/Every page answering this question gives you two opposite instructions and names no compound — except one, which names the wrong one. The molecules that make espresso bitter were isolated from real brewed coffee and they are neither caffeine nor tannin: they are made during roasting, and their taste thresholds have been measured. Sourness turns out not to be the same thing as pH. And the shot most people actually have — sour and bitter at once — is the one case none of those pages addresses, even though its mechanism is published.Fri, 11 Sep 2026 00:00:00 GMThttps://beansandbarista.com/blog/how-to-dial-in-espresso/https://beansandbarista.com/blog/how-to-dial-in-espresso/Every dial-in guide converges on the same recipe, and none of them says where it came from. It came from a survey: in 2017 the SCA asked 275 baristas what they actually do, and published the averages. The definition those averages were measured against defines grind size circularly — the right grind is whatever hits 20 to 30 seconds — and the only mathematical model of espresso says to ignore brew time entirely, because past a certain fineness, grinding finer extracts less and varies more. That is the part that wastes beans.Thu, 10 Sep 2026 00:00:00 GMThttps://beansandbarista.com/blog/how-many-grams-of-coffee-per-cup/https://beansandbarista.com/blog/how-many-grams-of-coffee-per-cup/There is no answer to this question until somebody says what a cup is, and the kitchen holds at least six different ones — from the 125 ml a Moccamaster counts to the 240 ml the FDA defines. On one certified machine, the only thing called a cup is 5 oz while the smallest drink it pours is 8. The answerable question is grams of coffee per gram of water, and the number of published answers to that is smaller than the internet suggests: the SCA has exactly one, and the document it is usually credited to does not contain it.Tue, 08 Sep 2026 00:00:00 GMThttps://beansandbarista.com/blog/do-you-need-a-coffee-scale/https://beansandbarista.com/blog/do-you-need-a-coffee-scale/Every page selling you a coffee scale quotes the same number: 0.1 g. That number is readability — how finely the display rounds — and it is not a statement about error. Acaia publishes both figures for its own $250 scale, and they are not the same. Which means the case for weighing coffee has to be made somewhere else, and it can be: the error a scale removes is not a tenth of a gram, it is closer to three grams.Mon, 07 Sep 2026 00:00:00 GMThttps://beansandbarista.com/blog/what-is-crema-in-coffee/https://beansandbarista.com/blog/what-is-crema-in-coffee/Crema is carbon dioxide that was dissolved under pressure and had nowhere to go when the pressure dropped. That makes it a good gauge of how much gas your coffee still had — roast degree, days since roasting, minutes since grinding — and a poor gauge of everything else. In one experiment the thickest foam collapsed fastest, and the strongest cups had the shortest-lived crema.Sat, 05 Sep 2026 00:00:00 GMThttps://beansandbarista.com/blog/what-is-coffee-extraction/https://beansandbarista.com/blog/what-is-coffee-extraction/Extraction is one number: how much of the dry coffee ended up in the liquid. Around 30% of a roasted bean can dissolve at all, and the famous window uses two-thirds of it. The parts everyone repeats — that flavours come out in a fixed order, that a 30-second bloom is settled science, that a shot should take 25 to 30 seconds — are the parts the research does not support.Fri, 04 Sep 2026 00:00:00 GMThttps://beansandbarista.com/blog/sca-golden-cup-standard/https://beansandbarista.com/blog/sca-golden-cup-standard/The two numbers everyone quotes come from a 1957 paper. The standard SCA certifies coffee makers against today quotes neither of them — it asks for a brew strength of 1.15–1.55%, which is a wider window than the one on the chart. Here is how to measure your own brew, and how much the target is worth once you have.Thu, 03 Sep 2026 00:00:00 GMT