Inactivation of Salmonella, Shiga Toxin-producing E. coli, and Listeria monocytogenes in Raw Diet Pet Foods Using High-Pressure Processing

Abstract

Pet food formulated with raw meat can pose health risks to pets and humans. High-pressure processing (HPP) was evaluated to achieve a 5-log reduction of Salmonella, E. coli STEC, and L. monocytogenes in commercial raw pet foods and maintain a 5-log reduction throughout post-HPP storage. Three formulation types that varied in the amounts of striated meat, organ meat, bone, seeds, and other ingredients (fruits, vegetables, and minor ingredients) designated as A-, S-, and R-formulations were used.Eight raw diet pet foods, consisting of three beef formulations (A-, S- and R-Beef), three chicken formulations (A-, S-, and R-Chicken), and two lamb formulations (A- and S-Lamb), were inoculated with 7 log CFU/g cocktails of Salmonella, E. coli STEC or L. monocytogenes, HPP at 586 MPa for 1–4 min, and stored refrigerated (4°C) or frozen (−10 to −18°C) for 21 days with microbiological analyses at various time intervals.A- formulations (20–46% meat, 42–68% organs, 0.9–1.3% seeds, and 10.7–11.1% fruits, vegetables, and minor ingredients) inoculated with Salmonella and treated at 586 MPa for at least 2 min achieved a 5-log reduction 1 day post-HPP and maintained that inactivation level during frozen storage. A- and S-formulations inoculated with E. coli STEC and treated at 586 MPa for at least 2 min achieved a 5-log reduction from day 6 of frozen storage.L. monocytogenes was more HPP resistant than Salmonella and E. coli STEC. S-formulations containing chicken or beef and stored frozen post-HPP had lower inactivation of L. monocytogenes compared to A-formulations containing chicken or beef. S-Lamb had higher frozen storage inactivation (5.95 ± 0.20 log CFU/g) compared to chicken (2.52 ± 0.38 log CFU/g) or beef (2.36 ± 0.48 log CFU/g). HPP coupled with frozen storage time was effective in achieving and maintaining a 5-log reduction of Salmonella and E. coli STEC while L. monocytogenes was more resistant and requires further optimization to achieve a 5-log reduction.

Keywords

• High-pressure processing
• Listeria monocytogenes
• Pathogen reduction
• Raw diet pet foods
• Salmonella
• Shiga Toxin-producing E. coli