Location: UWM Student Union-Wisconsin Room
Abstract
The seminar will begin with a brief history of coffee. The growth and processing of coffee to the green “bean” is then discussed. The unroasted coffee bean has a characteristic odor (green coffee beans will be passed around during the presentation for comparison to roasted beans).
The roasting of the beans is dominated by the Maillard reaction and Strecker degradation. Some of the compounds that have been identified as important flavor and aroma compounds are β-damascenone (cooked apple), 2-furfurylthiol (the dominant “coffee” smell of freshly brewed coffee), 2-isobutyl-3-methoxypyrazine (earthy), guaiacol (spicy), 2,3-butanedione (artificial butter), and 4-hydroxy-2,5-dimethyl-3(2H)-furanone (caramel).
The stage at which roasting is stopped has traditionally been done by color (after roasting test batches). The whole roasting process takes place 8-12 minutes, followed by rapid cooling to slow further reactions. Coffee roasted by the speaker (in his office!) will be sampled.
All coffee drinkers know that leaving coffee on a burner rapidly ruins the brew. This chemistry will be discussed, as will “staling” – the degradation of roasted coffee by exposure to air.
The final part of the talk will be a discussion of the health issues surrounding coffee. The compounds cafestol and kahweol can raise cholesterol slightly, but are absorbed by paper filters.
This talk is aimed at general audiences, chemists, and barristas.