Studies On Processing Technique Of Clear Pumpkin Beverage

In this paper, the measure for extracting pumpkin juice with mixed enzymes was studied, and the comparison between mixed enzymatic liquefaction method and blanching method had been made. Some factors influencing the extraction efficiency and the clarification results were analyzed systematically. The conditions of extraction and clarification were optimized. It was aimed chiefly at providing scientific basis for developing and utilizing pumpkin resource.The experimental results showed that the extraction results with blanching method were that the productive rate of juice was 71.8%, the total sugar extraction efficiency from pumpkin was 8.97% accounting for pumpkin pulp weight, the soluble solid materials was 4.08%. The results showed that the ratio of pectinase 0.03%,cellulase 0.7% and gluconmylase 0.04% were optimal through L9(34)orthogonal test on the basis of single factor tests of pectinase, cellulase and gluconmylase. The optimal conditions of mixed enzymatic liquefaction should be performed in 50℃for 3h at pH4.5 through orthogonal test, the productive rate of juice was 89.2%, total sugar extraction efficiency was 24.13% accounting for pumpkin pulp weight, soluble solid materials was 11.48%. Mixed enzymatic liquefaction method was a better one because of its higher productive rate of juice, total sugar extraction efficiency and soluble solid materials.The nutrients of pumpkin juice were little influenced because enzymatic liquefaction temperature was lower. The extracts liquefied by mixed enzymes was light yellow and delicate fragrancesmell.Clear pumpkin beverage was prepared by centrifugal clarification,chitosan clarification and ultrafiltration clarification.The experimental results showed that centrifugal clarification method was best for nutrients preservation, the total sugar remains was 99.89%, the pectin remains was 63.87%, the protein remains was 88.71%, but its transmittance was 93.3%. Chitosan clarification method was better for nutrients preservation, the total sugar content,the reducing sugar content and the soluble solid materials lost little more than that of untreated juice, the pectin content and protein content lost more than that of untreated juice, the pectin remains was 36.45%, the protein remains was 79.03%, and its transmittance reached 98.1%. The optimal conditions for chitosan clarification were adding 0.6g/L of chitosan in 50℃at pH4.0. Pumpkin juice was ultrafiltrated by using experimental membrane separation module,the transmittance of pumpkin juice reached 98.9%,the total sugar content,the reducing sugar content,the total acid content and the soluble solid materials lost little more than that of untreated juice, the pectin content and protein content lost much more...