Effects of enzymatic treatment on the physicochemical properties and antioxidant activity of hawthorn pectin

The effects of enzymatic treatment on the physicochemical properties and antioxidant activity of natural hawthorn pectin (CK) were evaluated using a series of characterization methods. The results indicated that four modified pectin preparations (MPE, MPLE, MPME, and MCE, respectively obtained through treatment with pectinase, pectin lyase, pectin methylesterase, and cellulase) all showed a low methoxy content. MPLE had the highest galacturonic acid (Gal A, 92.01%) content and the highest degradation temperature (135 ℃). MPME had the lowest molecular weight (3.59 kDa) and MCE had the smallest particle size (238.0 nm). Infrared spectroscopy (FTIR) indicated that the enzymatic treatment did not change the primary structure of pectin. Scanning electron micrographs (SEM) showed that the four modified pectin preparations were more fragmented and irregular. Antioxidant activity of the pectin preparations was evaluated by determining their radical scavenging ability (hydroxyl radical and ABTS radical) and reducing power. The IC50 for hydroxyl radical and ABTS radical of all modified pectin preparations was lower than CK. The reducing power of MPE and MPME was higher than that of CK. Different enzymes modification methods played an important role on the characterization of pectin. Enzymatic modification methods offer great promise for the application of hawthorn pectin in functional products.