Extraction and characterization of pectin from Premna microphylla Turcz leaves.

In this work, response surface methodology (RSM) and microwave pretreatment were used to extract pectin from Premna microphylla Turcz leaves (PMTL). The process variables were optimized by the isovariant central composite design to improve the pectin extraction yield. The optimum conditions obtained were as follows, extraction time 2 h, temperature 90 °C, pH 2 and liquid-solid (LS) ratio 50 mL/g. The extraction yield was 18.25% under these conditions, which was close to the predicted value (17.60%). Then the pectin was characterized by gas chromatographic (GC), spectrophotometric (UV-visible Spectroscopy) and spectroscopic (Fourier transform infrared) methods. The galacturonic acid content was 82.75%, and on this basis, the other monosaccharide composition analysis illustrated that pectin from PMTL was also composed of rhamnose, arabinose, mannose, glucose and galactose in a ratio of 2.96:1.17:1.04:8.07:2.05. The pectin of PMTL had an esterification degree of 62.50% and it showed good antioxidant activity. Taken together, the pectin of PMTL could be used as potential additive in food industry.