Optimization of microwave-assisted extraction of pectin from cupuassu (Theobroma grandiflorum) pod husk as an alternative for waste valorization of Amazonian fruits

Abstract This study aimed to optimize the extraction process of pectin from cupuassu pod husk powder by microwave-assisted extraction method, using response surface methodology (RSM). The effects of three variables: irradiation time, pH and solvent ratio, as well as their interactions, were analyzed to determine the optimal extraction conditions with the best process yield. The results indicated that the optimum conditions were pH 1.8, irradiation time of 20 min and solvent ratio of 20 mL/g, to obtain 10.82% yield. Characterization of the extracted pectin showed that obtained pectin is classified as high methoxyl (HMP), which highlights its applicability in the food industry as a gelling, thickening, emulsifying and stabilizing agent in products that require the presence of high levels of soluble solids, such as sugar, and under acidic pH conditions. Key parameters such as equivalent weight of 741.55 ± 1.73 mg/mol, moisture of 9.8 ± 0.19% and ash content of 10.19 ± 0.25%, key characteristics to evaluate the properties of pectin, were also determined. Finally, fourier-transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), thermal analysis (TGA and DSC), and scanning electronic microscopy (SEM) revealed structural characterization, thermal stability and morphology of the obtained pectin.