Effect of extraction condition on the chemical and emulsifying properties of pectin from Cyclea barbata Miers leaves

Cyclea barbata Miers is a tropical indigenous plant. The pectin extracted from Cyclea barbata Miers leaves (CBMP) has unique gelling characteristic that strongly depends on the extraction condition. This study aims to determine the chemical and emulsifying properties of CBMP extracted under conditions that deteriorate its gelling ability. CBMP extractions were performed using 5 and 50 mM HNO3 with 40 ppm H2O2, and 2 mM NaOH at 80°C for 3 h. Acid increased degrees of methylation (DM) and acetylation (DAc), and protein content of the obtained CBMP; while alkali extraction decreased DM but increased DAc. Depolymerization of CBMP to 20-80 kDa was observed when acid, alkali, and long extracting time were used. CBMP extracted using 5 mM HNO3 contained 66% DM, 2% DAc and showed better emulsifying properties than other depolymerized CBMP. Emulsion forming and stabilizing abilities of such CBMP resulted from the appreciable amount of protein (6%) to adsorb at the oil-water interface, and the suitable molecular weight (80 kDa) of pectin to provide sufficient thickness of hydrated layer for emulsion stabilization. Extraction under severe conditions resulted in the chemical structure modification which improves the emulsifying properties of CBMP and its potential use as emulsifier.