Combined effects of hydrostatic pressure, temperature, and pH on the inactivation of spores of Clostridium perfringens type A and Clostridium sporogenes in buffer solutions.
To develop a spore inactivation strategy, the effect of 15-min hydrostatic pressure treatments (550 and 650 MPa) at 55 and 75 degrees C in citric acid buffer (4.75 and 6.5 pH) on spores of 5 isolates of Clostridium perfringens type A carrying the gene that encodes the C. perfringens enterotoxin (cpe) on the chromosome (C-cpe), 4 isolates carrying the cpe gene on a plasmid (P-cpe), and 2 strains of C. sporogenes were investigated. Treatments at 650 MPa, 75 degrees C and pH 6.5 were moderately effective against spores of P-cpe (approximately 3.7 decimal reduction, DR) and C. sporogenes (approximately 2.1 DR) but not for C-cpe (approximately 1.0 DR) spores. Treatments at pH 4.75 were moderately effective against spores of P-cpe (approximately 3.2 DR) and C. sporogenes (approximately 2.5 DR) but not of C-cpe (approximately 1.2 DR) when combined with 550 MPa at 75 degrees C. However, when pressure was raised to 650 MPa under the same conditions, high inactivation of P-cpe (approximately 5.1 DR) and C. sporogenes (approximately 5.8 DR) spores and moderate inactivation of C-cpe (approximately 2.8 DR) spores were observed. Further advances in high-pressure treatment strategies to inactivate spores of cpe-positive C. perfringens type A and C. sporogenes more efficiently are needed.
Paredes-Sabja
D
D
Food Process Engineering Group, Department of Food Science and Technology, College of Agricultural Sciences, Oregon State University, Corvallis, OR 97331, USA.
Gonzalez
M
M
Sarker
M R
MR
Torres
J A
JA
D003013:Clostridium / Q000502:physiology*; D003016:Clostridium perfringens / Q000502:physiology*; D015169:Colony Count, Microbial; D005506:Food Contamination / Q000032:analysis / Q000517:prevention & control*; D005511:Food Handling / Q000379:methods*; D005519:Food Preservation / Q000379:methods*; D006863:Hydrogen-Ion Concentration; D006874:Hydrostatic Pressure; D013171:Spores, Bacterial; D013696:Temperature; D013997:Time Factors