Optimization of gallic acid-enriched ultrasonic-assisted extraction from mango peels

Gallic acid is recognized as a notable bioactive compound among secondary polyphenolic metabolites. In the current study, gallic acid-enriched extracts were obtained from mango peels using different solvents (ethanol or water) via ultrasound-assisted extraction, and optimized yields were compared with the conventional extraction technique (decoction). Independent variables for the optimization through response surface methodology were ethanol concentration (0-60%), solvent ratio (10-50 mL/g), temperature (30-60.), and time (10-30 min) for ethanolic extraction. However, extraction carried out by using water had extraction conditions of pH (2-8), solvent ratio (20-0mL/g), extraction temperature (40-70.), and time (30-60 min). The optimized yield of gallic acid obtained through ethanol was 5.75 +/- 0.21 mg/g, whereas 3.14 +/- 0.24 mg/g of gallic acid was quantified in extraction through water. The results were compared with the aforementioned conventional method of decoction, and it was concluded that the ethanolic extracts of mango peels showed the highest gallic acid yield and total flavonoid contents. The obtained extracts could be a potential source of polyphenolics, especially gallic acid, for use in nutraceuticals as well as in other food applications.