Impact of immature coffee fruits and water addition during spontaneous fermentation process: Chemical composition and sensory profile

Abstract

Background

Coffee fermentation process influences the final coffee composition and the sensory aspects which define the quality of the beverage. In this study, coffee fruits underwent spontaneous self-induced anaerobic fermentation using samples with two percentages of immature fruits in submerged and solid-state processing. The effects on the physicochemical composition and sensory quality of coffees were evaluated.

Results

The two percentages of immature fruits corresponded to 11.0 and 0.3% of unripe fruits. The percentage of immature fruits significantly altered the initial content of sugars (sucrose, glucose, and fructose), ash, and titratable acidity. The water addition during the fermentative process did not significantly influence final moisture, proteins, citric acid, and propionic acid concentrations. Compared to the solid-state, the submerged process gave rise to coffees with lower concentrations of ethanol, glycerol, ash, lipids, succinic, and acetic acids. Coffee fermented with 0.3% of immature fruits showed higher lactic acid production in submerged fermentation (67.44 mg/g), and higher concentrations of ethanol (42.84 mg/g) and glycerol (1.68 mg/g) in solid-state fermentation. All coffees produced were classified as specialty coffees with a score above 84 points. However, the submerged fermented coffee with 11% immature fruit stood out with notes of caramel, brown sugar, honey, orange, lemon, floral, nut, yellow and red fruits.

Conclusions

This study confirmed that spontaneous fermentation can be used to produce specialty coffees. Differentiation in sensory attributes can be achieved through the addition of water and varying the percentage of green fruits during the fermentation process. Up to 11% of immature fruits did not compromise coffee quality.

How to cite: Ferreira LJC, Casé IN, Bertarini PLL, et al. Impact of immature coffee fruits and water addition during spontaneous fermentation process: Chemical composition and sensory profile. Electron J Biotechnol 2024;69. https://doi.org/10.1016/j.ejbt.2024.04.001.