Methods for processing biological tissue

A method for processing fixed biological tissue using a bioburden reduction process (BRP) solution comprising glutaraldehyde and polysorbate-80 to remove phospholipids, the method comprising:

• (a) attaching the fixed biological tissue to a laminate or frame;
• (b) covering the laminate or frame at least partially with fabric to create a leaflet sub-assembly;
• (c) immersing the leaflet sub-assembly in a first container of the BRP solution, the BRP solution consisting essentially of purified water, glutaraldehyde, polysorbate-80, and a buffer to maintain a pH within the range of about 7.3 to 7.5 during processing;
• (d) heating the first container to a temperature of about 37° C. for a period of time between about four and sixteen (4-16) hours to remove phospholipids from the tissue using the BRP solution;
• (e) removing the leaflet sub-assembly from the first container;
• (f) immediately immersing the leaflet sub-assembly in a second container of the BRP solution;
• and
• (g) heating the second container to a temperature of about 37° C. to remove phospholipids from the tissue using the BRP solution,
• wherein the total time the tissue is exposed to the BRP solution is no more than about twenty-four hours to mitigate or reduce calcification of the tissue.