Clarification and concn. of fruit and vegetable juices - by ultrafiltration in at least two stages with retained material in molecular wt. range 15000 to 25000

摘要

Process is described for clarifying juice which has been extracted from fruit or vegetables by pressing. The process is of the type in which the expressed juice is passed through an ultrafiltration membrane which gives a primary clarified filtrate and a primary retained material which is passed through a second ultrafiltration membrane which yields a second clarified filtrate and second retained material. At least one of the ultrafiltration membranes is suited to hold retained material with a nominal molecular weight within the range of 15,000-25,000. Pref. the pH value of the expressed juice is determined and the temp. adjusted before clarification to within plus or minus 3 deg.C of (80-6pH) deg.C. At least one stage of ultrafiltration has an inlet pressure between 3 and 5 kg per square cm and an outlet pressure between 1 and 2 kg per square cm. Pref. a secondary filtrate is added to the primary filtrate and the primary retentate is diluted before secondary ultrafiltration. The process is to separate, concentrate or purify solutes in the molecular weight range 15,000-25,000, partic. for the extn. of pectins, starches, proteins, tannins etc. This ultrafiltration process requires less time, labour and energy than previous extn. methods to produce the above prods. No filtration additives are required and the clarified filtrates are sterile without heat treatment. Waste matter is reduced and prod. yield higher than with conventional extn. processes.