Lysozyme Stability
The product stability, measured as “residual activity”, is a function of two key parameters: temperature and pH.
TEMPERATURE
Lysozyme is a very stable molecule to temperature. The loss of activity of Lysozyme Hydrochloride in solid form products at room temperature is 5% over a five-year period.
Even at higher temperatures Lysozyme maintains an appreciable stability with a loss of activity of 9% when stored at 45°C for 12 months, and of 17% at 56°C for six months. The heat resistance of the crystalline Lysozyme at high temperatures is also remarkable. Studies show that crystalline Lysozyme maintains 100% of its activity at 160°C for an hour.
Lysozyme in aqueous solution (22%) is less stable than Lysozyme in solid form. Studies indicated a shelf-life of 6 months at room temperature, while when refrigerated at 4°C, the loss of activity was only 5% after 18 months.
pH
Lysozyme is active at pH intervals of 3.0 to 9.0. Lysozyme’s activity rate and stability are highest in acidic solutions between pH 3.5 and 7.0. Some literature shows that with a pH between 4.5 and 5.5, Lysozyme can endure 100°C temperature for several minutes, while with a pH of 8.0, HEW Lysozyme is destroyed in 15 minutes at a temperature of 65°C.
Sugar and/or a saline solution at 2.5% stabilizes Lysozyme against heat. With sugar, the protection is greater with a pH of 3.2 than with a pH of 6. An elevated concentration of salt can inhibit Lysozyme activity against bacteria.