Optimization of Gallic Acid-Rich Extract from Mango (Mangifera indica) Seed Kernels through Ultrasound-Assisted Extraction

Different types of agro-waste provide potential substrates for the extraction of bioactive compounds. Mango waste (e.g., peels and seeds) is one such example and may serve as a source of gallic acid, a well-known bioactive compound classified as a secondary polyphenolic metabolite. Here, we explored the efficacy of ultrasound-assisted extraction (UAE) in extracting gallic acid from mango seed kernels using different solvent concentrations (0-60%), solvent-to-sample ratios (10-50 mL/g), temperatures (30-60 degrees C), and times (10-30 min). The maximum yield of gallic acid (6.1 +/- 0.09 mg/g) was obtained when using a 19.4% solvent concentration, a 29.32 mL/g solvent-to-sample ratio, and the extraction was conducted at 38.47 degrees C for 21.4 min, similar to the values predicted by the model equation. As compared to the conventional extraction procedure, the extract obtained by the optimized method was found to be significantly different in total phenolic content, total flavonoid content, and radical scavenging activity. Non-significant differences were observed in antimicrobial activity. The results indicate that mango seed kernels may be a good source of phenolics, and those phenolics can be effectively obtained through an optimized UAE method. Hence, mango seed kernels may be utilized as a suitable source of extracting phenolics in nutraceutical and food applications.