How can animal fat become rancid while it's frozen ?

Answer by  ChrisH (53)

Animal fat does not turn rancid in optimal freezing conditions, but may get freezer burn which can be just as bad. Also, if the fat is frequently thawed and then frozen it will become rancid from the process. The quality of the animal fat, the freezer and the container it is in will all ultimately play a role.

Answer by  Bill777 (65)

Freezing things just slows down the natural growth of bacteria, it does not stop it entirely. In many cases, other means of preservation are better: smoking, pickling, and so on.