Scientific Publications by FDA Staff

J Food Prot 2015 Jan;78(1):146-50

Effect of Sporulation Temperature on the Resistance of Clostridium botulinum Type A Spores to Thermal and High Pressure Processing.

Marshall KM, Nowaczyk Ii L, Morrissey TR, Loeza V, Halik LA, Skinner GE, Reddy NR, Fleischman GJ, Larkin JW

The purpose of this study was to determine the effect of sporulation temperature on the resistance of Clostridium botulinum type A spores of strains 62A and GiorgioA to thermal and high pressure processing (HPP). Spore crops produced in Trypticase-peptone-glucose-yeast extract broth at four incubation temperatures (20, 27, 37, and 41 degrees C) were harvested, and heat resistance studies were conducted at 105 degrees C (strain 62A) and 100 degrees C (strain GiorgioA). Resistance to HPP was evaluated by subjecting the spores to a high pressure (700 MPa) and temperature combination (105 degrees C, strain 62A; 100 degrees C strain GiorgioA) in a laboratoryscale pressure test system. The decimal reduction time (D-value) was calculated using the log-linear model. Although the time to sporulation for GiorgioA was shorter and resulted in higher spore concentrations than for 62A at 20, 27, and 37 degrees C, GiorgioA did not produce a sufficient spore crop at 41 degrees C to be evaluated. The heat resistance of 62A spores was greatest when produced at 27 degrees C and decreased for spore crops produced above or below 27 degrees C (D105 degrees C-values: 20 degrees C, 1.9 min; 27 degrees C, 4.03 min; 37 degrees C, 3.66 min; and 41 degrees C, 3.5 min; P < 0.05). Unlike 62A, the heat resistance behavior of GiorgioA spores increased with rising sporulation temperature, and spores formed at the organism's optimum growth temperature of 37 degrees C were the most resistant (D100 degrees C-values: 20 degrees C, 3.4 min; 27 degrees C, 5.08 min; and 37 degrees C, 5.65 min; P < 0.05). Overall, all spore crops were less resistant to pressure-assisted thermal processing than thermal treatment alone. Sporulation temperature has an effect on the resistance of C. botulinum spores to heat and HPP, and is characteristic to a particular strain. Knowledge of the effect of sporulation temperature on the resistance of C. botulinum spores is vital for the production of spores utilized in thermal and high pressure inactivation studies.