Study On Extraction And Properties Of Seeding Watermelon

Seeding watermelon mainly originated from the northwest xinjiang. Seeding watermelon is as a kind of agricultural waste to abandon, it not only wasteful, but also polluting the environment. If abandoned seeding watermelon will save, it not only can solve the problem of waste residue to pollute the environment, but also save resources. It can also increase the application value of the seeding watermelon. Pectin has good thickening, stabilizing, emulsifying and gelling effect, it widely used in food industry, cosmetics, pharmaceutical, printing and dyeing and other industries. Therefore, the seeding watermelon as raw material, extracted pectin by ultrasonic assisted acid formulation, ethanol precipitation to separate pectin, to determined the quality index of seeding watermelon pectin, gelatin and rheological property. The results show that:(1)According to the single factor and response surface methodology experiment on ultrasonic assisted extraction process of pectin from seeding watermelon. The optimal process parameters for ultrasonic assisted extraction of pectin from seeding watermelon by acid extraction were 139 W, solvent pH1.9, leaching temperature 67℃, ultrasonic treatment 54 min. Under these conditions, the pectin yield reached up to 13.85%, Extraction yield of validation experiments is 13.58%. The results indicates that, the mathematical model is valid for predicting the extraction of pectin from seed-using watermelon.(2)According to the the single factor and response surface methodology experiment on ethanol precipitation to separate pectin. The result of the optimal process parameters for ethanol precipitation to separate pectin as follows: the precipitation temperature was 37℃, ethanol concentration was 82%, concentration ratio was 2/5, the dosage of ethanol was three times the volume of concentrated pectin, the theoretical value of pectin yield can reached to 13.30%. The actual value was 13.02%, The results indicates that, the mathematical model is valid for predicting the extraction of pectin from seeding watermelon.(3)According to the determination of seeding watermelon pectin quality indicators, the loss on drying of seeding watermelon pectin was 3.47%, the total ash content was 3.98%, the degree of esterification was 38%, pH4.64, galacturonic acid was 81.12 %, they comply with QB2484-2000 standard requirements. Seeding watermelon pectin viscosity average molecular weight is Mη=138728.78. Seeding watermelon pectin was dark brown, slightly deeper than standard pectin.(4)Concentration of pectin was 2.0 %, gel forming time was 24 h, Ca2+ conceration was 20 mg/g, pH was 5.0, suger content was 30%, texture characteristics of gel was the best.(5)Seeding watermelon pectin solution is a typical non-newtonian fluid, pH within the scope of 2.5~6, along with the increase of pH value and viscosity of the pectin solution is reduced, with the increase of heat treatment time and temperature, seeding watermelon pectin viscosity decreases, when the heat treatment time for more than 25 min, heat treatment temperature about 100℃, the pectin solution show the characteristics of Newtonian fluid, pectin solution increases with the increase of calcium ion concentration and viscosity.