Effect of High Hydrostatic Pressure on Psychrotrophic Clostridium spp. Isolated from Spoiled Vacuum Packaged Fresh Beef

Introduction: Contamination of beef with endospores of psychrotrophic Clostridium spp. has led to incidences of blown-pack spoiled meat in Canada.  Interventions used during carcass dressing processes are not sufficient to destroy endospores.  High hydrostatic pressure may be a viable option for reducing the population of endospores on fresh meat; however, little is known about the pressure resistance of psychrotrophic Clostridium spp. isolated from fresh meat.

Purpose: The objective was to determine the resistance endospores of psychrotrophic Clostridium spp. to high hydrostatic pressure in minced raw beef.

Methods: Endospores of three psychrotrophic Clostridium spp. isolated from blown-pack spoiled beef (BP-1, BP09-01 and BP09-13) and Clostridium estertheticum ATCC 51377 were used.  Beef was minced using a food processor, inoculated with endospores, and transferred to pressure resistant tubes.  Samples were exposed to 400 MPa at 4, 40 or 70°C for 0, ramp, 4, 8, 15, 30 and 60 min. 

Results: After pressure treatment at 400 MPa at either 40 or 70°C, viable cells of BP-1, BP09-01, BP09-13 and C. estertheticum ATCC 51377 were not detected after 8 min of treatment.  Endospores of BP09-01 were destroyed by pressure treatment for 4 min at all temperatures.  Counts of BP-1 and BP09-13 were reduced by 1 log (CFU/ml) after 4 min at all temperatures.  Endospores of BP09-13 were detected after 30 min of treatment at 400 MPa and 4°C but C. estertheticum ATCC 51377 was not detected after 15 min at 400 MPa and 4°C. 

Significance: Spoilage of fresh meat due to the growth of psychrotrophic Clostridium spp. can result in significant economic losses for the meat industry.  High hydrostatic processing of vacuum packaged beef at 40°C and 400 MPa for 8 min could mitigate the spoilage caused by psychrotrophic Clostridium spp.