14A-13

J. YOON¹, T. H. Kim², K. H. Kim², W. J. Lee¹, and S. H. Youn³. (1) Department of Food Science, Kangnung National University, 123 Jibyun Dong, Kangnung, Kangwon Do, 210-702, South Korea, (2) Department of Chemical Engineering, Ajou University, San 5, Wonchun Dong, Paldal Gu, Suwon, Gyunggi Do, 442-749, South Korea, (3) Pall Asia International, Ildong Bldg. 4F 968-5,Daechi 3-Dong, Gangnam-Gu, Seoul, South Korea

5'-Ribonucleotides are high added value products used as flavor enhancers in food industry (5'-IMP, 5'-GMP) or have important applications in the pharmaceutical industry (5'-CMP, 5'-UMP, 5'-AMP). In view of quality of enzyme recovered and savings in separation cost, ultrafiltration can be considered one of the most promising methods to prepare specific enzymes from natural resources. Ultrafiltration as a downstream processing technique for the recovery of 5'-phosphodiesterase from malt rootlet extract was investigated.

Our objective was to examine the operating parameters associated with ultrafiltration suitable for partial purification and concentration of 5'-phosphodiesterase.

Ground malt rootlets were leached with 20 fold mass of distilled water for 10 h. The extract was filtered through gauze and the filtrate was centrifuged for 10 min at 10,000 rpm. The supernatant was then used for ultrafiltration. A cassette-type ultrafiltration module with polyethersulfone membrane was used. At each given cross-flow rate, permeate flux was studied with transmembrane pressure (TMP) to achieve the optimum operating condition. The permeate flux with concentration factor was then investigated at the optimum TMP and cross-flow rate.

Optimum process parameters were transmembrane pressure of 10 psi and cross-flow rate of 2.0 L/min. Permeate flux decreased linearly with the logarithm of the concentration factor (CF) up to 6.25. The retentate with CF being 6.25 showed an increase in specific activity by 1.5 times, suggesting both concentration and partial purification of 5'-phosphodiesterase were accomplished. Subsequent diafiltration with distilled water (3 diavolumes) decreased soluble solid content from 1.9% to 1.2%, although it did not increase specific activity.

These results suggest that ultrafiltration can be successfully used for partial purification and concentration of 5'-phosphodiesterase from malt rootlet extract.