Is there a problem with using coffee just after it cools after roasting… or should we wait some time between roast and grind and brew?
Thats a good question- slightly different than asking if its better to wait. Waiting, letting the coffee “rest” or “degas” does help in creating better flavor. “Problem” is a definite negative.
Its counter intuitive to the idea of fresh coffee, but letting the beans sit for anywhere from a day to even 3-4 days will make a big difference as to when the coffee is at its peak aroma, flavor, taste. Some espresso blends really hit their stride at a week after roasting. It all depends on your personal taste but time is definitely part of the recipe.
As an experiment try brewing three cups at 2 days and 4 days and one immediately after roasting. Just roast them on different days and try brewing all three at the same time to taste the difference.
What you’ll see on the just-out-of the-roaster one when brewing is an effect called “bloom” that’s the coffee puffing up due to the co2 escaping. There will be less or none on the other two.
And thats the answer to your original question, if there’s a problem with brewing straight from the roaster, its because of bloom. When the hot water hits the yet-to-degas coffee all that gas tries to escape and causes the bloom. The escaping gas prevents the water from really well saturating the grinds before dripping on through. As the water is trying to get in to saturate the grounds the gas is pushing back out just as hard. So while it looks wet, its not as wet as it could be and the water isn’t leaching out the good stuff as effectively. …While it can be argued that once ground, the coffee should be as degassed as its ever going to be. In practice it doesn’t seem to be true.
Once you’re past the coffee degassing, which takes about a day, then its just a matter of where you think the coffee is hitting the mark before grinding it up. You’ve probably already noticed that a few days after you’ve roasted you get that experience of “Wow, THAT’S a good cup of coffee! ” All you have to do is start taking notice of that experience for each kind of coffee you roast, how you roasted it, and plan ahead for it
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Coffee can be maddening, especially in a home roaster. There’s a lot of generalities, rules of thumb, but very few recipes set in stone to master it. If you generally do the same things the same way each time however and only change one factor (as if thats possible) you’ll eventually begin doing it by second nature.
…Kind of like cooking a fried egg. You just know how to do it and you don’t need charts and graphs and a slide rule to determine the proper BTU’s of energy or the coefficient of friction in teflon.
Just do it. Break some eggs, roast some coffee. Its easy.