Volatile compounds in espresso resulting from a refined selection of particle size of coffee powder

Analysis of Volatile Compounds, Composition, and Thermal Behavior of Coffee Beans According to Variety and Roasting Intensity

“…Furans are cyclic ethers mainly found in condensates from carbohydrates that undergo browning reactions. As green coffee beans contain large amounts of sugars, mainly sucrose, these compounds are formed through thermal processes, such as coffee roasting, when degradation and rearrangement of carbohydrates, ascorbic acid, and unsaturated fatty acids occur [19,37,38]. The thermal degradation of d-glucose and sugar polymers into furanic compounds as major decomposition products was also reported by Kim et al [39].…”

“…Methylpyrazine was identified in all the studied coffee samples, the highest amounts being detected in C1, C2, and C4 (>4% of the total detected volatile organic compounds). Pyrazines provide various odors, such as nutty, roasted, corn, hazelnut, potato or earthy aromas, depending on the substituents of the pyrazine ring; pyridine is related to bitter, fishy or burnt odors, while pyrrole provides nutty notes [19].…”

“…The influence of coffee species and varieties, geographical origins, harvesting, roasting, grinding, and brewing on the quality of coffee, from raw beans to the final cup of espresso coffee, has been extensively studied [19,20]. Coffee quality depends on many factors, such as the production system, the chemical composition of the green or roasted beans, the roasting process, and brewing [17,20,21].…”

“…During roasting, the formation of undesirable or toxic compounds, such as polycyclic aromatic hydrocarbons and acrylamide, is also possible [22]. Grinding roasted coffee beans is crucial to releasing volatile organic compounds in the brewing of coffee [19]. The main constituents of coffee can also be affected by roasting conditions, ground-particle size, and brewing methods [20].…”

“…The volatile organic compounds belonging to different chemical classes identified in roasted coffee, such as alcohols, aldehydes, esters, furans, ketones, phenols, pyrazines, pyridines, pyrroles, and sulfur compounds, define the sensory properties of coffee [19,20]. Some chemicals, such as furans, may harm human health [19]. Volatile organic compounds with low odor thresholds make significant olfactory contributions to coffee flavor [27].…”