Study On Extracting And Purifying Of Pectin From Apple Pomace

At present, the production of pectin in China is still lagging. Because the traditional production in which ethanol is the precipitant costs higher, but the technology of salting out which costs lower is not prefect. Based upon the present condition, we studied the extracting and purifying technology about pectin from apple pomace. It involved the following aspects: choosing the optimal acidolysis reagent, determining the optimal parameters of extracting technology of pectin, comparing the effect of pectin decoloration, attempting the methods of purification, determining the optimal parameters of technology of pectin precipitation with salt, determining the condition of desalting, etal. The result shows:(1) The value of pH of solution should be adjusted with phosphoric acid and sulphurous acid (1:2) at extracting pectin from apple pomace,and the pectin with the best color and quality was obtained.(2) The absorbance at 630nm is the index of transmittancy of pectin solution. The yield of pectin can be converted by absorbance of pectin solution by the method of carbazole colorimetric at 530nm.(3) The optimal parameters of pectin extracted by acid are :95℃,pH 2.0, 2.0h,the ratio of pomace and water 1:2.At the above condition, the yield of unrefined pectin is 14.62%.(4) The effect of decoloration with resin is better than active carbon, and the method of decoloration with resin is suitable for industrial production. At the condition of the test, the optimal parameters of decoloration with resin are: temperature 60℃, velocity of flow speed 200ml/h.(5) The carbohydrate can be removed about 96.35% by dialysis, the protein can be removed about 61.49% by the method of trichloroacetic acid , and the loss rate of pectin is only 3.40%. The method of purification applied in the test is practicable.(6) The aluminum sulfate is determined as the optimal precipitant in precipitating pectin, the optimal condition of salting out is: adding 6ml saturated solution of aluminum sulfate into 100ml pectin solution, adjusting the value of pH to 4.5 with ammonia water, and keeping Ih at 60 ℃.(7) The optimal proportion of solution of desalting(v/v) is:60% ethanol + 3% hydrochloric+37% water, adding 5g pectin dried into 200ml solution of desalting, and stirring for about 30min.Under this condition, the yield of pectin is 0.7645g; the ash content is 4.34%.The new ideas brought forth in the study are:(1) The technical condition of producing pectin with less cost was systematically studied.(2) The purification technology of pectin was attempted in this study, especially new opinion was brought forth on decoloration of pectin.(3) The study can provide application foundation and technical support for comprehensive utilization of apple pomace.