Filter & Brewing
Pour-over, immersion and cold brew — grind, temperature, agitation and the paper itself.
Paper vs metal coffee filters: what actually reaches your cup — cafestol, sediment and taste
Paper keeps all but a trace of the cholesterol-raising cafestol out of the cup. Metal is not one thing: a reusable nylon filter measured against paper let through eight times as much, a French press 35 times. What that means in cholesterol, and what is and is not known about taste.
Coffee maker not hot enough? Find out whether it's the machine or the cup before you fix anything
In a healthy brewer, most of the heat you miss is lost after the coffee leaves the basket, and the two problems have different fixes. The SCA caps a certified carafe at 85 °C on purpose, UC Davis could not taste 87 °C from 93 °C once extraction was matched, and a thermometer in the basket tells you which problem you have.
Espresso puck prep: what WDT, distribution tools and tamping actually do
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.
How to dial in espresso, when the recipe everyone gives you is a survey result
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.
How many grams of coffee per cup? First, whose 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.