Electron beam processing of freeze-dried and frozen raw pet food to eliminate Salmonella and Listeria monocytogenes: efficacy and nutritional impact

Introduction Frozen and freeze-dried raw pet food products are at high risk for the presence of pathogens including Listeria monocytogenes and Salmonella spp. This study investigated the efficacy of electron beam (eBeam) technology freeze-dried and frozen raw pet food to eliminate pathogen risks and assess whether nutritional composition is impaired. Methods Eight different frozen and freeze-dried pet food products representing diverse protein sources and formulations were inoculated with high titer multi serovar cocktails of L. monocytogenes and Salmonella spp. Products were treated with incremental target eBeam doses of 2.5–25 kGy to determine inactivation kinetics and calculate the D 10 values in the different matrices. Nutritional impact was assessed at commercially relevant doses of 9.5–12.7 kGy using proximate and macro/ micronutrient profiling. Results The D 10 values for L. monocytogenes ranged between 0.65 ± 0.01 kGy and 1.15 ± 0.04 kGy, while those for Salmonella spp. ranged between 0.55 ± 0.02 kGy and 1.93 ± 0.10 kGy across the 8 different pet food products. eBeam doses between 5 kGy and 9.5 kGy could effectively achieve >5-log reduction of these key pathogens suggesting that the commercially relevant doses (between 9.5 kGy and 12.7 kGy) were sufficient for substantial microbial inactivation. Proximate composition (moisture, crude protein, crude fat, crude fiber, and ash), mineral content, amino acid profiles, fatty acid profiles, and the majority of vitamins (D3, B1, B 2 ) remained statistically unchanged ( q > 0.05) across all product formats evaluated. Vitamin A and vitamin E were the most sensitive to eBeam treatment in selected products. Discussion These findings demonstrate that eBeam processing is an effective non-thermal kill-step for frozen and freeze-dried raw pet food to eliminate Listeria spp. and Salmonella spp., while preserving the overall nutritional quality. Current commercially employed doses can be expected to achieve >5-log reduction of these pathogens if present in these products.