APPLICATION OF LACTIC FERMENTATION AND ULTRASOUND-ASSISTED EXTRACTION FOR THE VALORIZATION OF Coffea arabica CASCARA

Abstract: Coffee is one of the most widely consumed beverages worldwide (after water), with a global production reaching 176.2 million 60-kg bags in the 2024/2025 harvest season. Coffee processing generates cascara, which can be 30% of the coffee mass, depending on the processing method and species. Coffee cascara is a valuable source of bioactive compounds, whose recovery represents an attractive valorization strategy due to their antioxidant and health-promoting properties for food and pharmaceutical industries. This study aimed to evaluate the effects of lactic fermentation on the recovery of caffeic acid, chlorogenic acid, and caffeine from coffee cascara by ultrasound-assisted extraction. Submerged fermentations of Coffea arabica fruit were carried out with L. acidophilus (LA) and L. plantarum (LP) at 37°C. After 96 hours of fermentation, cascara was sun-dried to ~10% moisture content, ground and sieved (1 mm). Extractions were performed in triplicate using a 1:10 solid-to-liquid ratio, with distilled water, at room temperature. Ultrasound-assisted extraction was performed in an Ultrasonic bath (CPX 5800H, Bransonic, USA) at 40 kHz for 50 minutes. Extracts were centrifuged at 4,500 rpm for 10 minutes and filtered (0.22 µm) before analyses. Caffeic acid, chlorogenic acid and caffeine were quantified using a Thermo Scientific Vanquish™ HPLC system equipped with a triple quadrupole mass spectrometer, using acidified water with 0.1% (v/v) formic acid as mobile phase, spray voltage of 3912 V, sheath gas of 24, auxiliary gas of 2, ion transfer tube temperature of 325°C, and vaporizer temperature of 400°C. The results were analyzed using one-way ANOVA followed by the Tukey test (p<0.05) and expressed in mg.g⁻¹ of dry cascara. The results showed that fermentation significantly affected the concentrations of caffeic acid, chlorogenic acid, and caffeine. Caffeic acid increased from 0.170 ± 0.001 mg.g⁻¹ in the non-fermented cascara to 0.188 ± 0.001 and 0.186 ± 0.001 mg.g⁻¹ after LP and LA fermentation, respectively. Chlorogenic acid increased from 0.695 ± 0.024 (non-fermented) to 1.941 ± 0.024 (LP) and 2.015 ± 0.081 mg.g⁻¹ (LA), with no significant differences between the fermented treatments. In contrast, caffeine decreased from 7.136 ± 0.216 mg.g⁻¹ in the control to 6.865 ± 0.090 (LP) and 6.508 ± 0.193 mg.g⁻¹ (LA). The increase in caffeic and chlorogenic acids after fermentation can be due to microbial enzymatic activity, which can alter the plant cell wall matrix and release bioactive compounds. Fermentation-induced acidification may enhance ultrasound-assisted extraction by increasing solvent penetration and mass transfer. The reduction in caffeine may be attributed to its partial microbial biotransformation, although this effect depends on the microbial strain and fermentation conditions. Therefore, the fermentation ultrasonic strategy represents a promising approach to recovering bioactive compounds from coffee cascara, promoting its valorization and the development of circular production systems.

Acknowledgments: CNPq, CAPES, FAPEMIG