Efficient extraction of pectin from spaghetti squash (Cucurbita pepo L. subsp. pepo) peel by electron beam irradiation combined with ultrasound: Structural characterization and functional properties

This study investigated the effects of acid extraction, electron beam irradiation (EBI) extraction, ultrasound extraction, and combined EBI and ultrasound extraction on the yield, structure, and functional properties of pectin from spaghetti squash ( Cucurbita pepo L. subsp. pepo ) peel. The established extraction kinetics model indicated that the combined EBI and ultrasound extraction exhibited a synergistic effect, resulting in a pectin yield (13.50 %) higher than that obtained from acid extraction (6.55 %), EBI extraction (10.91 %), and ultrasound extraction (7.56 %). The pectin produced through the combined method (EUSP) demonstrated a low degree of esterification (DE) (34.77 %) and molecular weight (M w ) of 83 kDa. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses revealed that EBI and ultrasound significantly disrupted the internal structure of the pectin. Rheological analysis indicated that the combined treatment reduced the viscosity characteristics of the pectin solution. EUSP exhibited good thermodynamic properties, emulsifying characteristics, antioxidant activities, and prebiotic activity. These findings provide a theoretical basis for the combined EBI and ultrasound extraction of pectin and offer insights for the efficient utilization of spaghetti squash peel and the application of pectin in the food industry.