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Beta-Galactosidase Retention by Hollow Fiber Membranes¹

Department of Food Science and Nutrition, The Ohio State University, Columbus 43210 and Ohio Agricultural Research and Development Center, Wooster 44691

ABSTRACT

The method of loading Aspergillus oryzae ß-galactosidase in a hollow fiber membrane unit influence both enzyme retention an loss of activity during operation. Operated in the normal ultrafiltration mode with enzyme in the recirculating retentate, there was about 5% leakage across the membrane and approximately 50% loss of enzymatic activity after 2 h. Loading enzyme in the sponge layer of the membrane markedly increased leakage across the membrane, but there was minimal loss of activity (<10%) of the enzyme retained. Average leakage was 30, 40, and 7% when the membrane reactors were run in the recycle, backflush, and static modes. Leakage of enzyme across the membrane was not related to a change in molecular weight (100,000 daltons) of the enzyme nor to defects in the membrane.

Results of enzyme retention cannot be explained by the lumen pore size theory. Therefore, a dynamic membrane theory is proposed that states that synthetic membranes are dynamic structures whose molecular size exclusion can be influenced by combination of variables including flux, flow, solvent, solute, and membrane polymer type.

¹ Approved as Journal Article 132-80 The Ohio Agricultural Research and Development Center, Wooster.