Abstract: The present disclosure provides, among other things, methods of drying porcine thyroid gland material and manufacturing DTE comprising vacuum drying porcine thyroid gland material in a way such that the temperature of the porcine thyroid gland material is maintained above a threshold temperature. Since applying vacuum, or reducing pressure, has a cooling effect on the porcine thyroid gland material, maintaining the porcine thyroid gland material above a threshold temperature can be achieved by gradually reducing pressure while simultaneously increasing the heat applied to the porcine thyroid gland material during the period of gradual pressure change. Such methods are advantageous in reducing bioburden (killing and impeding the growth of microorganisms) while maintaining therapeutic levels of thyroid hormones, as compared to certain methods of drying porcine thyroid gland material and/or manufacturing DTE known in the art.