Study On Extraction Of Pectin From Kuerle Fragrant Pear Purification And Thermal Stability

Xinjiang Korla Pear (Pyrus bretschneideri Rehd.) belongs to the Rosaceae, the white pear of Pyrus species. It has a cultivation history of about 1400-2000 years. It is well known for its thin, juicy and sweet both at home and abroad.Pectin is a complex polymer material and can be applied to a wide range of food, medicine, industry and so on. So its use can be seen at a very wide range. A large number of basic and applied research work have been made toward the pectin. They were extracted mainly from orange peel, passion fruit peel, naringin and hesperidin by using water and ethanol solvent from at home and abroad.At present, the planting area of pear is expanding gradually and the production is continued to increase in China. But the contradiction of supply exceeding demand is quite prominent because of constraints of the seasonal pear production and consumption capacity. At the same time, a large amount of droped fruit and the defective pears are produced[5,6],however, their pectins are not extracted at home. If this field can be researched and developed, profound potential for development will be produced.Used Pear as raw materials, this paper tries to achieve the re-using of droped fruit and defective fruit by the extraction and content determination of pectin in Pear, compares influences of three methods toward the content of fruit rubber, that is, the traditional acid extraction, microwave-assisted extraction and ultrasonic extraction, decolorats by the use of activated carbon, and finally ethanol precipitation method using high purity of pectin, and studied the physical and chemical properties of pectins in Pear. The results show that:(1) Optimization of single-factor experiments and orthogonal experimental design method are chosen. The best process parameters of traditional acid extraction of pectin is:extraction temperature 90℃, extraction time 80min, pH 4.5, solid liquid ratio 1:20, pectin yield is 4.79%; the best process parameters of microwave-assisted extraction of pectin is as follows:microwave power 400W, extraction time 5min, pH 3.5, solid liquid ratio 1:9, pectin yield is 4.89%; the best process parameters of ultrasonic extraction:pH 5, extraction power 420W, extraction time 45min, solid liquid ratio1:25 pectin yield is 2.21%.(2) Conclusion got by optimized single factor selecting experiment:active carbon dosage is 1g/100ml, pH is 7, temperature is 70, decolorization time for 60 min, pigment absorption rate of 78.5percent.(3) Degree of esterification, moisture, ash, pH, galacturonic acid content were determined by GB standard, and all the parameters of Korla Pear pectin was found to be in accord with the specification of GB. The solubility, hot-stability and gel properties were compared Korla Pear pectin with Commodities pectin. Key words:pear pectin; extraction; decolor; analysis of physical-chemical properitie and Application of pectin.