… Now these toxins once formed are heat stable, so you can boil it all you want but the toxin is NOT destroyed, and if the food is ingested, it will kill you, unless your institution can get botulinum antitoxin in time. It still will be a severe illness requiring a significant period of time on life support at the best.
I agree with everything you said, except that botulinum toxin is heat stable. Dormant c. botulinum spores do require 121° C for 20 minutes to be killed, but the toxin they produce is much more sensitive to heat.
Botulinum toxin is a two subunit protein with a total molecular weight of about 150,000. It is a potent neruotoxin that blocks acetylcholine release at the neuromuscular junction with a median lethal dose about 1 nanogram. Heating it to boiling temperature will denature the protein and render it non-toxic. Studies have shown that brief exposure to temperatures as low as 60° C (140° F) inactivates it.
Licciardello, J.J., J.T. Nickerson, C.A. Ribich, and S.A. Goldblith. (1967). Thermal inactivation of type E botulinum toxin. Appl Microbiol. 15:249-256.
The theoretical required cooking times for inactivation of type E Clostridium botulinum toxin (5,000 ld(50) mouse units per 0.5 ml) in haddock fillets of various sizes were calculated by graphical integration of the toxin inactivation rate and heat penetration data. The results indicated that normal cooking procedures should suffice to inactivate this amount of toxin. This conclusion was substantiated by the following additional experimental observations which revealed that the original experiments had been conducted under conservative conditions. First, maximal heat stability of the toxin was found to occur at about pH 5.5, with decreasing resistance upon increasing pH. The theoretical cooking times were based on destruction of the toxin at pH 6.7. The pH of radio-pasteurized inoculated haddock, when toxin production had occurred, was on the alkaline side, at which condition the toxin is heat-labile. Second, when spoilage was discernible in radio-pasteurized inoculated haddock, the toxin titer was low, about 50 LD(50) mouse units per 0.5 ml. Third, the toxin was adequately inactivated in toxic fillets after deep-fat frying for 3 min at 375° F (190.6° C) or after pan frying for 5 min per side at 400° F (204.4° C). Fourth, in this study, residual toxin activity was assayed by intraperitoneal injection of mice. It was shown that the oral toxic dose was 50 to 100 times greater than the intraperitoneal toxic dose.
Licciardello, J.J., C.A. Ribich, J.T. Nickerson, and S.A. Goldblith. (1967). Kinetics of the thermal inactivation of type E Clostridium botulinum toxin. Appl Microbiol. 15:344-349.
Rate of inactivation curves for the "free" toxin, prototoxin, or activated toxin in crude filtrates of Clostridium botulinum type E were nonlinear, consisting of a fast inactivating rate followed by a slow inactivating rate. Thermodynamic parameters were calculated over a temperature range of 125° to 145° F (51.7° to 62.8° C) for the two different inactivation rates. Energy of activation was low at the lower temperature and high at the higher temperature. The thermal requirement for inactivating similar concentrations of the "free" toxin, prototoxin, or activated toxin was considered to be the same.
