Stability of Clostridium botulinum Toxin in Sample Extracts Under Freezing and Refrigeration Conditions

Studies performed to evaluate food safety from C. botulinum involve the inoculation of spores into the test matrix, then storing the samples under controlled temperatures. Portions of the food are removed at designated times and analyzed for the presence and/or quantity of toxin. Scientists question the effect of storage variables such as temperature and time on the activity of C. botulinum toxin. This study shows good toxin stability for extracts prepared from sterile cultures containing only type A, E and nonproteolytic type B C. botulinum. Extracts prepared from inoculated sterile culture media as in this study may be stored for long periods of time under refrigeration or freezing with no loss in toxin activity.The study also showed that these extracts may be frozen and thawed up to 3 times with no loss in toxin formation. It is important to note that the results of this study are specific for toxin extracts prepared from sterile media inoculated with only C. botulinum spores.