Ultrasound-assisted enzymatic extraction and structural characterization of pectin from the tender leaves of Abelia macrotera

ObjectiveTo clarify the physicochemical properties, microscopic structure, monosaccharide composition, relative molecular mass, and structural characteristics of pectin in the tender leaves of Abelia macrotera.MethodsPectin from the tender leaves of Abelia macrotera was extracted by ultrasound-assisted cellulase method. The microscopic structure was observed under scanning electron microscope. The monosaccharide composition was determined by high performance liquid chromatography. The relative molecular mass was determined by polysaccharide hydrolysis derivatization. The possible structure was inferred by infrared spectroscopy.ResultsThe yield of pectin from the tender leaves of Abelia macrotera is 23.38%, the esterification degree was 1.17%, and the galacturonic acid content was 72.16%. The pectin is in the form of flakes with cracks. The monosaccharides mainly consist of galacturonic acid, glucose, arabinose, galactose, rhamnose, mannose and xylose. The weight average molecular weight (Mw) and number average molecular weight (Mn) are 7.069×105 and 3.434×105, respectively, with an Mw/Mn of 2.06. It has typical spectrum characteristics of pectin absorption.ConclusionThe pectin extracted from the tender leaves of Abelia macrotera by ultrasound-assisted enzyme method has a low linear structure and is mainly composed of RG-I type structure containing shorter side chains, which meets the commercial requirements.