Inactivation of Salmonella, Shiga Toxin-producing E. coli, and Listeria monocytogenes in Raw Diet Pet Foods Using High-Pressure Processing
Alvin Lee, Nicole Maks-Warren, Viviana Aguilar, Karolina Piszczor, Brittany Swicegood, Mu Ye, Joshua L. Warren, Edward O’Neill, Mark Fleck, Süsy Tejayadi
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 ofSalmonella,E. coliSTEC, andL. monocytogenesin 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 ofSalmonella,E. coliSTEC orL. 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 withSalmonellaand 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 withE. coliSTEC and treated at 586 MPa for at least 2 min achieved a 5-log reduction from day 6 of frozen storage. L. monocytogeneswas more HPP resistant thanSalmonellaandE. coliSTEC.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 ofSalmonellaandE. coliSTEC whileL. monocytogeneswas more resistant and requires further optimization to achieve a 5-log reduction.