Volatile Compounds of Fermented Coffees

Coffee is the most consumed beverage in the world, and Brazil is its largest producer. The quality of the coffee is directly influenced by agriculture practices, harvest, and post-harvest procedures, drying and storage conditions, before roasting. In the last few years, many coffee producers are using fermentation as a mean of increasing beverage quality, increasing its value and profits. As this process is relatively new in the world, there is little information on what chemical compounds are responsible for the increase of quality and complexity of coffee flavor. Five fermentation processes were conducted in one farm of commodity and other of specialty coffee in Brazil. The coffee berries were harvested and fermented in closed containers for at least 6 days, dried and peeled. Raw and roasted coffee were ground, weighed and SPME extracted using a DVB/CAR/PDMS fiber. The fiber was desorbed in gas-chromatograph equipment, with DB-WAX column, helium as the carrier gas, and fragmentation by MS. Compounds were identified by NIST library and LRI. About 54 and 108 compounds were identified in raw and roasted coffee, respectively. From these: 11 and 17 compounds, from raw and roasted coffee respectively, had increase in all samples of fermented coffee and they had positive impact on the beverage, with fruits, sweets, nuts, chocolate, wine, and caramel aromas; and 10 and x compounds, from raw and roasted coffee respectively, had decrease in all samples of fermented coffee, and had negative impact on the beverage, with ether, chemical, smoked, pungent, and medicinal aromas. Besides that, it was notable the increase in acids (3,3%) and alcohols (10,1%) in raw coffee. The fermentation of coffee changes the composition of its aroma, developing substances with good sensorial aspects and reducing others which decrease the quality, explaining the huge increase of quality by this special fermentation process.