Optimization of antioxidative phenolic compound extraction from freeze-dried pulp, peel, and seed of Burmese grape (Baccaurea ramiflora Lour.) by response surface methodology

The aim of this work was to optimize the extraction of antioxidative phenolic compounds from freeze-dried pulp, peel, and seed of Burmese grape using response surface methodology (RSM) with the target to maximize TPC, DPPH, and FRAP. Solvent (ethanol) concentration (%), temperature (°C), and time (min) were taken as independent variables by factorial screening for the extraction procedure. After extraction, the antioxidant activity of all samples was determined employing 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity, total phenolic compounds (TPCs), and ferric reducing antioxidant power (FRAP) assay. The experiment’s optimum conditions were 80% solvent concentration, 69.01 °C temperature, and 30 min for pulp. The optimum extraction conditions were found at 80 °C for 29.39-min incubation time using 52.12% concentrated solvent for seed. For peel, the solvent concentration of 41.62% was found optimum when the temperature of 50 °C and 30-min incubation time were used. The actual values of TPC, FRAP, and DPPH for freeze-dried pulp, peel, and seed extracts were close to the predicted values, which confirms the models’ validity. The analysis of variance (ANOVA) showed that the models were significant for TPC, DPPH, and FRAP values of peel, pulp, and seed at different levels (p < 0.001 to p < 0.05). The composite desirability of pulp, seed, and peel were 0.94, 0.98, and 0.85, respectively, which suggests that the developed model could be effectively used for antioxidants’ extraction from freeze-dried pulp, peel, and seed of Burmese grape.