Ultrafiltration and Separation Process Optimization of Hen Egg White Lysozyme as Natural Antimicrobial Enzyme

천연 항균 효소제 난백 lysozyme의 한외여과 조건 최적화

  • Lee, Eun-Young (Department of Foods and Nutrition, Ewha Women's University) ;
  • Woo, Gun-Jo (Department of Foods and Nutrition, Ewha Women's University)
  • 이은영 (이화여자대학교 식품영양학과) ;
  • 우건조 (이화여자대학교 식품영양학과)
  • Published : 1998.04.01

Abstract

Hen egg white lysozyme (HEWL) is very valuable as a natural preservative in food processing due to its selective bactericidal activity. HEWL which traditionally isolated by crystallization or freeze drying was simply separated from 13 different hen egg white (HEW) proteins by a single-step ultrafiltration. Freeze dried HEW (0.25%, w/v) dissolved in a citrate-phosphate buffer (pH 4.6) was ultrafiltered with a PM30 membrane under various operating conditions, by changing concentration, temperature, transmembrane pressure $({\triangle}P_T)$, and stirring speed. Optimum separation conditions were decided when maximal flux was obtained. Under the optimum separation conditions, the effect of membrane material and fouling on flux as time passed as well as lysozyme concentration, protein concentration, specific activity (SA) in the permeate were measured. Best separation conditions of HEWL with PM30 membrane were sample concentration 0.25%, temperature $35^{\circ}C$, ${\Delta}P_T\;30\;psi$, and stirring speed 300 rpm. During the first 12 min, the flux of YM30 was higher, but at the steady-state it was lower than that of PM30. The SA of the PM30 permeate was over 2 times higher in spite of the lysozyme and protein concentration being lower than that of YM30 permeate. The flux of 5 times used PM30 decreased 30% compared to a new PM30, but both had the same tendency in flux decrease when time passed. Both of them reached a steady-state after 35 min and remained at 70% of the initial flux. In the PM30 permeate, the lysozyme concentration and SA were 110 units/mL and 2,821 units/mg protein, respectively. Therefore, PM30 membrane separation was very effective for separation of antimicrobial lysozyme.

Keywords

ultrafiltration;lysozyme;antimicrobial enzyme