Stirred maceration extraction of custard apple (Annona squamosa L.) peel

Abstract The custard apple, or Annona squamosa L., is one of the most popular fruits in tropical areas like Vietnam. The goal of this study was to use stirred maceration extraction to value-add the custard apple fruit’s peel. On the total polyphenol content (TPC) and radical scavenging activity by DPPH and ABTS assays of the extracts, various values of extraction duration (30 - 60 min), ethanol concentration (40 - 70%), solvent to solid ratio (15 - 30 mL/g), and temperature (40 – 70°C) were studied. The best condition for the variables under investigation was determined using the Box-Behnken design and response surface methodology. Multiple linear regressions were used to determine the coefficients defining the effects of temperature, extraction duration, ethanol concentration, and solvent-to-solid ratio on the dependent responses. The ethanol concentration of 52%, the extraction duration of 51 min, the temperature of 60°C, and the solvent-solid ratio of 26 mL/g were determined to be the ideal values. The optimum TPC under these circumstances was 94.08 mg GAE/g, and the antioxidant activity was 536.64 μmol TE/g for the DPPH assay and 1310.83 μmol TE/g for the ABTS assay.