Ultrasound-assisted extraction of finger citron pectin: Process optimization, structure, physicochemical and functional properties.

The finger citron (Citrus medica L. var. sarcodactylis Swingle) has been consumed as a nutraceutical food and traditional Chinese medicine in China for thousands of years. This study adopted response surface methodology to optimize the ultrasound-assisted extraction process of finger citron pectin (FCP). The optimized parameters for FCP were obtained as an ultrasonic temperature of 77 °C, ultrasonic power of 525 W, treatment time of 107 min, and solid-liquid ratio of 1:34 g/mL, with a maximum FCP yield of 18.97%. Comparative analyses of ultrasound-assisted extracted pectin (FCP-UAE) and conventional heating extracted pectin (FCP-CHE) revealed that ultrasound significantly influenced FCP's properties, including extraction yield, degree of esterification, monosaccharide composition, and microstructure. It also improved FCP's emulsifying and antioxidant capacities by adjusting composition and structure. This study clarifies the effect of UAE on FCP's physicochemical and functional properties, laying a scientific foundation for its development and industrial application as a multifunctional additive.