Microwave time tunes broccoli-stem pectin fine structure and calcium gelation for sustained resveratrol release.

In this study, the effects of microwave-assisted (MAE) extraction on the structural, functional and gel properties of broccoli stem pectin (BSP) were investigated. BSP was predominantly homogalacturonan (HG)-type pectin. BSP-150 s exhibited the highest galacturonic acid (GalA, 66.9 ± 0.5%), the largest molecular weight (Mw, 216.0 ± 0.7 kDa), and a moderate degree of esterification (DE, 34.6 ± 0.6%), yielding Ca2+-cross-linked hydrogels with the greatest hardness and water-holding capacity. Thermogravimetry analysis indicated higher onset and peak decomposition temperatures at 150 s, while XRD diffraction analysis revealed slightly denser amorphous packing. Multivariate analysis (PCA/PLSR) further demonstrated that GalA and Mw were the principal positive predictors of hardness and WHC, with ζ-potential contributing additively. Moreover, BSP-150 hydrogels exhibited effective resveratrol (RES) encapsulation and controlled release. These findings confirm that microwave-assisted (MAE) is an efficient method for obtaining broccoli stem pectin with superior gelation capacity and potential applications.