Green ultrasound-assisted extraction of bioactive compounds of babassu (Attalea speciosa) mesocarp: Effects of solid-liquid ratio extraction, antioxidant capacity, and antimicrobial activity

Abstract

Babassu mesocarp (Attalea speciosa, Family: Arecaceae) is a by-product of kernel oil manufacture, reported as a rich source of phenolic compounds of biotechnology potential due to its anti-inflammatory, wound-healing, antioxidant, and antimicrobial properties. In this work, were investigated a greener protocol to maximize the recovery of bioactive compounds by Ultrasound-Assisted Extraction (UAE) using ethanol as a food-grade solvent, purposing future applications in foods. Moreover, the effect of solid/liquid ratio (1:4, 1:10, and 1:25 w/v) on extraction was also evaluated. Results showed extracts with 1.2 g of mesocarp with 30 mL ethanol 94% (1:25 ratio w/v), for 20 min, at 20°C, yields high values of Total Phenolic Contents (TPC: 5124.86 ± 350.13 mg GAE/100 g), flavonoids (TFC: 477.45 ± 23.07 mg QE/100 g), antioxidant capacity (FRAP: 4037.56 ± 187.26 µmol TEAC/100 g, DPPH• remaining from 10 to 38% after stabilization). Moreover, the DPPH• assay also suggests that each solid-liquid ratio recovers antioxidant compounds able to react with DPPH by differential Kinect, which can conveniently favor usability and enhance oxidative stability in food applications. For example, the extract obtained by the 1:4 ratio reacted very fast with DPPH• (less than 1 min), while on the 1:25 ratio, the stabilization of DPPH• is slower, taking more than 120 min. For the first time, raw babassu mesocarp ethanolic extract inhibited Gram-negative bacteria Escherichia coli and S. Enteritidis activity, as shown by Disk-diffusion assay. This study indicated that Ultrasound-assisted technology could be used as a greener protocol to recover high amounts of polyphenols from babassu mesocarp using food-grade solvents with antioxidant and antimicrobial potential.