title_body: Why is it not recommended to drink coffee immediately after it's roasted?
upvoted_answer: Fresh off the roast, coffee has high levels of carbon dioxide and nitrogen (based?) gasses. These gasses will greatly contribute to retro-nasal activity as well as initial flavors (think carbonated water). The most apparent flavor one gets from this is metallic. At my work, 4 days is considered minimum for serving and tasting, although there's always exceptions.