Technical assessment of nanofiltration process for concentration of cranberry juice and recovery of benzoic acid

Summary This work investigated cranberry juice nanofiltration using a plate and frame pilot plant equipped with NF99 membrane to concentrate cranberry juice and simultaneously separate benzoic acid from cranberry juice. The influences of ultrafiltration pretreatment were also considered. The results indicated that UF pretreatment can improve permeate flux and consequently the concentration factor and concentration degree. In both cases, the dominant fouling mechanism of cranberry juice nanofiltration was complete blocking. However, the UF pretreatment could reduce the fouling phenomena. With nanofiltration of ultrafiltration pretreated cranberry juice at pH 2.5 and 4 MPa of operating pressure; concentration factor, concentration degree, final solid content, the total rejection of benzoic acid and recovery yield of soluble solid were 4.23, 4.14, 21.3 o Brix, 0.703 and 0.938 respectively. In the permeate, the benzoic acid content on dry matter increased more than 10 times compared with the feed. These results indicate that it is promising to apply nanofiltration for not only recovering benzoic acid from cranberry juice but also concentrating that juice simultaneously with benzoic acid recovery.