Multitarget optimization of citrus pectin extraction using microwave-assisted technique and citric acid

One of the main biopolymers used in the food industry is pectin, primarily due to its thermal stability and resistance to strong inorganic acids. This study optimized the extraction conditions—specifically temperature and time—for obtaining pectin from citrus peels using microwave-assisted extraction (MAE at 900 W) with citric acid (pH 2.48) as the solvent. The optimization considered yield, degree of esterification (DE), equivalent weight (EW), and methoxyl content (MTC) as response variables. For this, a central composite design was applied, varying the temperature (80, 120, and 160 °C) and time (1, 3, and 5 min). The ideal conditions to achieve a higher pectin yield with high DE, EW, and MTC were determined to be 160 °C for 5 min, predicting an efficiency of 35.76% with a DE 74.29%, EW 264.97 g/mol, and MTC 4.30%. These results were confirmed by validation studies, showing values within ± 10% of the predicted outcomes. Pectin samples in this study exhibited significant thermal stability, with polymer chain decomposition occurring between 150 and 250 °C and glass transition temperatures ranging from 92.78 to 94.96 °C. These findings suggest that using MAE and citric acid allows the production of high-quality pectin with excellent yield, offering promising applications in the food industry.