Predicting the stability of freeze-dried Fusobacterium mortiferum proficiency testing samples by accelerated storage tests

Abstract

Short-term, thermal degradation tests were performed at elevated temperatures of 55, 42, and 35 °C with freeze-dried proficiency testing samples of F. mortiferum. The loss of viable numbers of organisms was predicted for the samples at lower storage temperatures of 27.5 and 4 °C by applying calculated K values for the three elevated temperatures to the Arrhenius relationship. The predicted K values were within 1 SE of the K values obtained by least-squares analysis of the experimental data for the two lower storage temperatures. Application of accelerated storage tests for predicting stability at storage temperatures offers a number of benefits, including cost benefits, in assessing the stability of freeze-dried bacterial preparations used in proficiency testing programs.