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How in-house roasting changes what is in your cup
Why the gap between roast date and brew date matters more than most cafes admit
Most coffee is roasted somewhere else and shipped to the cafe that serves it. By the time it reaches the grinder, it might be two weeks old, or four, or more. That gap is not a scandal, but it does change what ends up in your cup. At Cozy Zephyr we have been roasting in-house since 2009, and the difference is not subtle.
What happens to coffee after roasting
Roasting drives out moisture and creates hundreds of aromatic compounds through a process called the Maillard reaction and, at higher temperatures, caramelisation. Those compounds are volatile. They start escaping the moment the beans come out of the drum. Carbon dioxide also off-gasses from freshly roasted beans for several days, which is why a bag of very fresh coffee will puff up if you seal it too soon.
The practical result is that coffee has a peak window. For espresso, most roasters find that window opens around five to ten days after roasting and closes somewhere around four to six weeks. For filter methods like V60 or Chemex, the window is a little earlier and the drop-off is gentler. Buying pre-roasted stock from a wholesaler makes it genuinely difficult to serve coffee within that window consistently.
What changes when a cafe roasts on-site
When you roast your own beans, you control the roast date. At Cozy Zephyr, Tsuyoshi roasts once a week, on Tuesdays, and the batch goes into the grinder the following day. By the time a customer orders a V60 on a Friday, the beans are three days old. That is inside the ideal window for filter brewing.
You also develop a much more direct relationship with the green bean. Pre-roasted stock arrives already transformed. Green beans arrive as a raw material, and you have to make decisions about them: how long in the drum, at what temperature, when to drop. Those decisions are where the flavour actually gets made, and making them yourself means you can adjust for the specific character of each origin rather than applying a one-size profile.
A note on what in-house roasting does not fix
Roasting in-house does not automatically mean better coffee. A poorly calibrated roast of excellent green beans will still produce a disappointing cup. The green bean quality matters enormously, which is why we source through an importer in Osaka who works directly with farms and can tell us the altitude, the processing method, and the harvest year.
It also requires consistency. Roasting the same bean twice and getting two different results is easy to do if you are not paying attention to drum temperature, airflow, and development time. Tsuyoshi keeps a roast log for every batch, noting the ambient temperature in the back room, the charge temperature, and the time to first crack. That log goes back to 2009.
If you want to see the roast log or ask about a specific origin, come in on a Tuesday morning. The drum is usually running by 7:30, before the shop opens.
Tsuyoshi Komatsu · Roasting · Freshness · Single origin · Pour over