Optimization and characterization of chestnut shell pigment extract obtained microwave assisted extraction by response surface methodology

The objective of this study is to find optimum conditions to valorize chestnut shell bioactive compounds with coloring pigments through microwave-assisted extraction. With this aim, response surface methodology with central composite design was used. Microwave power (800 W), extraction time (12 min) and solvent concentration (NaOH: 0.115 mol/L) are determined as the optimum conditions to maximize the responses like color value, total phenolic content and total antioxidant capacity. In the optimized extract (OE), Characterization of brown melanin like pigments are assessed by Spectrophotometer, Fourier Transform Infrared Spectrometer and major phenolics are identified as; gallic acid, ellagic acid, protocatechuic acid, catechin, and epicatechin as 0.53, 0.48, 0.46, 0.46, 0.14 mg/g dried weight (dw) with High Performance Liquid Chromatography, respectively. In terms of antibacterial activity, OE inhibits the growth of Staphylococcus aureus. Consequently, chestnut shells are successfully processed into natural coloring agents that are possessing strong brown color properties as well as high bioactive potential.