Optimizing ultrasonic-assisted extraction of phytocompounds from Spondias bahiensis bagasse

The Brazilian semiarid is a region characterized by having a great diversity of native fruit species, especially those of the Spondias genus. These fruits are widely consumed for their sensory characteristics of aroma and flavor and have been commonly reported as a source of phytocompounds with high antioxidant and antimicrobial capacity. However, there is still a lack of information about the processes for optimizing the extraction conditions of these substances. Thus, this study aimed to optimize the ultrasound-assisted extraction of phytocompounds from the Spondias bahiensis bagasse. The optimal conditions for ultrasound-assisted extraction were determined using a central composite rotational design (CCRD), where the independent variables were extraction time (minutes) in the ultrasonic bath (170 W; 35 kHz), ethanol concentration (%), and the ratio mass of residue/volume of solvent. The response variables were the content of total phenolic and antioxidant activity against the DPPH radical. The extract obtained under optimized conditions was evaluated regarding the content of bioactive compounds, phenolic profile, and antimicrobial activity. Optimal extraction conditions were obtained with 20 minutes of exposure to ultrasonic waves, using 55% ethanol solution and a mass/solvent ratio of 2.72. Under these conditions, 839.65 ± 26.48 mg GAE.100 g-1 dry matter (d.m.) were obtained for phenolic compounds and 1944.60 ± 45.49 mM TE.100 g-1 d.m. for antioxidant activity against the DPPH radical. The optimized extract also showed high antioxidant activity for the ABTS radical (26.82 ± 2.29 mM TE.g-1 d.m.), FRAP (571.33 ± 0.65 mM TE.g-1 d.m.), and iron chelating activity (60.45 ± 1.96%) when compared to other plant extracts. Flavonoid and anthocyanin contents were 5.51 ± 0.62 mg.g-1 and 0.53 ± 0.06 mg.g-1, respectively. The optimized extract also showed good results for antimicrobial activity (measured by the inhibition halo diameter) against Pseudomonas aurigenosas (9.17 ± 0.79 mm), E. coli (8.39 ± 0.42 mm), Salmonella sp. (7.00 ± 0.68 mm), and S. aureus (8.84 ± 0.44 mm). In conclusion, it appears that the optimization of obtaining phytocompounds, assisted by ultrasound, from Spondias bahiensis bagasse is a promising alternative for use in the food, chemical, and pharmaceutical industries since the optimized extract showed high antioxidant power and antimicrobial capacity.