The effects of pH, ionic strength (I), and selected antimicrobial substances on the lytic activity of egg white lysozyme over an extended storage period of 30 d were studied by observing the rate of clearing of a cell suspension of Micrococcus lysodeikticus. During prolonged storage, lysozyme activity remained relatively stable at pH 7 and ionic strength <0.10, whereas lower activity (P < 0.05) was observed at pH 9 and ionic strength >0.14. Lysozyme activity was highly stable (i.e., maintained over 90% of lytic activity from day 1 to day 30) in solutions of 1.0% sodium chloride, 100 ppm sodium nitrite, 4.0% ethanol, and 100 ppm butylated hydroxytoluene. Lysozyme activity also was stable (i.e., retained over 80% of lytic activity) in solutions of 0.1% sodium benzoate and 100 ppm butylated hydroxyanisol. The lysozyme activity was relatively stable (i.e., retained over 70% of lytic activity) in Solutions of 0.3% calcium propionate, 0.1% potassium sorbate, and 0.1% propyl paraben. About half (50%) of the lysozyme activity was retained in solution of 0.5% EDTA. Activity was lost when lysozyme was combined with 0.5% lactic acid, 4% acetic acid, and 100 ppm chlorine water.
Contribution No. 92—654-J from the Kansas Agricultural Experiment Station.