Characterization of edible film fabricated with HG-type hawthorn pectin gained using different extraction methods

In this study, four HG-type pectins were obtained using hydrochloric acid extraction (HA-HP), citric acid extraction (CA-HP), ultrasonic-assisted extraction (UA-HP), and microwave-assisted extraction (MA-HP). Four pectin films (HA-HPF, CA-HPF, UA-HPF, and MA-HPF) were prepared by a solution casting method, respectively. Compared to four pectins, the asymmetric COO - vibrational peak of UA-HPF, HA-HPF, and CA-HPF were blue-shifted (1604-1606 cm-1), while was red-shifted (1611 cm-1) in MA-HPF. The crystallinity was greater for HA-HPF and CA-HPF than UA-HPF and MA-HPF. Four pectin films all had relatively homogeneous surface morphology. CA-HPF had the best mechanical properties and oxygen barrier performance, HA-HPF had the best transparency. UA-HPF had the lowest hydrophilicity and water vapor permeability. MA-HPF had the best thermal stability. Our study shows that different physicochemical properties of HG-type pectins can influence the physicochemical properties of films. The difference of these properties gives the resulting film different possibilities for application.