"using chemical analyses and follow-up taste tests by humans trained to detect coffee bitterness, the scientists discovered the compounds that make coffee bitter and also how they form."
drumroll please. . .and the answer is going to be compounds formed during roasting, like chlorogenic acid. dark roasted coffees are always the bitterest, from the phenylindanes.
i guess the "scientists" doing this study are like, from mars or something, because anyone who's spent 10 minutes talking to a coffee chemist, to a pro taster, to long-time bccy pal paul songer, or the like, already knows this.
so let's take off our blindfolds and read the rest of the article. sigh.
sometimes you wish people would just read flament on google. for example, here.
please remember that bitterness in coffee should pleasant, as in dark chocolate and stout. anything more than that: overroasting!
bad coffee! the mermaid! avoid, dear readers, flee!