Profile of chemical compounds, aroma, and cup quality of arabica coffee from ohmic-heated carbonic maceration

In this study, we investigated the effects of ohmic-heated carbonic maceration on the chemical composition (including bioactive compounds), aroma, and cup quality of Arabica coffee. Coffee cherries were fermented at two temperature levels (31 ℃ and 36 ℃) and three durations (48,144, and 240 hours) in an ohmic-heated fermenter under carbonic (CO₂-rich, anaerobic) conditions. The coffee samples were analyzed using HPLC and GC-MS to identify bioactive and volatile compounds, and cupping tests were performed using the Specialty Coffee Association of America (SCAA) protocol. The results showed that increasing fermentation duration decreased 3-caffeoylquinic acid (3-CQA) and 4-CQA, while 5-CQA remained stable or increased at 36 ℃ for 240 hours. Trigonelline exhibited relative stability at low temperatures but declined at prolonged durations, particularly at 36 ℃. Caffeine concentrations peaked at intermediate durations before stabilizing. Sugar content generally decreased with increasing fermentation duration, with significantly lower levels observed after 10 days of fermentation. Principal component analysis of volatile compounds revealed distinct clustering patterns among treatments, with long fermentation durations positively correlated with the production of phenols, alcohols, pyrroles, benzenes, pyridines, and alkanes. Sensory evaluation using the SCAA protocol showed that four fermentation treatments provided slightly higher cupping scores (85.0–85.75) than the control (84.5), with flavor notes including nutty, flowery, lemony, brown sugar, spicy, fruity, and winey aromas. These findings indicated that Arabica coffee processed under ohmic-heated carbonic fermentation conditions exhibits measurable modulation of key chemical constituents, sugar content, and volatile composition, leading to improved cup quality and distinct sensory attributes within the studied processing conditions.