Growth of heat-treated enterotoxin-positive Clostridium perfringens and the implications for safe cooling rates.
Clostridium perfringens 790-94 and 44071.C05 carrying a chromosomal and a plasmid cpe gene, respectively, were used to determine differences in heat resistance and growth characteristics between the genotypes. Heat inactivation experiments were conducted using an immersed coil apparatus. Spore germination, outgrowth, and lag phase, together named GOL time, as well as generation times were determined during constant temperatures in fluid thioglycollate (FTG) medium as well as in vacuum-packed, heat-treated minced turkey. GOL time and growth were also monitored during cooling scenarios from 65 to 10 degrees C for 3, 4, 5, 6, and 7 h in vacuum-packed, heat-treated minced turkey. Spores of strain 790-94 were approximately 10-fold more heat resistant at 85 degrees C than those of strain 44071.C05, and strain 790-94 also had a higher temperature growth range in FTG. The higher growth range for a chromosomal enterotoxin-producing CPE+ strain was confirmed using two other strains carrying a chromosomal (NCTC8239) and plasmid (945P) cpe gene. Moreover, strain 790-94 had shorter GOL times at 50 degrees C in turkey and approximately half the generation time compared with strain 44071.C05 at temperatures > or = 45 degrees C in both FTG and turkey. Strain 790-94 increased with 0.3, 1.0, 1.7, and 2.0 logs, respectively, during cooling from 65 to 10 degrees C in 4, 5, 6, and 7 h, which was significantly higher than for strain 44071.C05. A maximum acceptable cooling time of 5 h between 65 and 10 degrees C is suggested.
Andersen
Karin G
KG
Department of Dairy and Food Science, Centre for Advanced Food Studies, LMC, The Royal Veterinary and Agricultural University, Rolighedsve, 30, DK-1958 Frederiksberg C, Denmark.
Hansen
Tina B
TB
Knøchel
Susanne
S
D003016:Clostridium perfringens / Q000235:genetics / Q000254:growth & development* / Q000502:physiology; D003257:Consumer Product Safety; D005511:Food Handling / Q000379:methods*; D005516:Food Microbiology; D005798:Genes, Bacterial; D005838:Genotype; D008461:Meat Products / Q000382:microbiology*; D013171:Spores, Bacterial; D013696:Temperature; D013864:Thioglycolates; D013997:Time Factors; D014618:Vacuum
D013864:Thioglycolates