Optimization of Low-Methoxy Pectin Extraction from Premna microphylla Turcz and Study on Its Processing Characteristics and Microstructure Properties

Response surface methodology was used to study the influence of the extraction rate, pH, extraction time and liquid-to-liquid ratio on the degree of esterification (DE) and the yield of Premna microphylla Turcz pectin. The microstructure and processing characteristics of pectin under the optimal extraction conditions were studied. The optimal extraction conditions for greatest yield (17.8%) were as follows:Extraction temperature 90℃, pH6, extraction time 67 min and ratio of material to liquid 24:1 mL/g, and obtained pectin showed the value of DE at 43.1%, containing 65.8% galacturonic acid and 3.9% protein, which had a typical infrared spectrum of pectin polysaccharide and multi-pleated reunion under scanning electron microscope observation. The water holding capacity and oil holding capacity of the pectin were assayed to be 6.52 and 6.03 g/g, respectively. The foaming power of pectin at 2% and 4% was 52.7% and 72.4%, respectively, and the foam stability after 30 min was 18.5% and 44.6%. In summary, the Premna microphylla Turcz leaves is a great source of low-methoxy pectin, and the Premna microphylla Turcz original low-methoxy pectin has potential application value as emulsifier, stabilizer and foaming agent for improving sensory quality of high-fat food system.