DOI: https://doi.org/10.15368/theses.2022.11
Available at: https://digitalcommons.calpoly.edu/theses/2567
Date of Award
3-2022
Degree Name
MS in Agriculture - Food Science and Nutrition
Department/Program
Food Science and Nutrition
College
College of Agriculture, Food, and Environmental Sciences
Advisor
Siroj Pokharel
Advisor Department
Animal Science
Advisor College
College of Agriculture, Food, and Environmental Sciences
Abstract
Within the last decade, pork consumption has steadily increased and continues to be the most consumed meat globally. However, pathogenic bacterial strains resistant to antibiotics have also been increasingly found in pig farms, animals, and the environment. Bacterial food poisoning cases due to Salmonella spp. and Escherichia coli (E. coli) O157:H7 appear to be linked with a variety of pork products. The meat industry has recognized that research is needed to combat the multi-drug resistance in foodborne pathogens with alternative methods of control. This study evaluated the effects of both E. coli- and Salmonella-specific lytic bacteriophages and lactic acid (LA) on E. coli O157:H7, Salmonella Enteritidis, Salmonella Montevideo, and Salmonella Heidelberg growth in raw pork loins ready for marination.
The efficacy of the treatments was determined after 1 h of application and marination. Lytic bacteriophage 5% significantly (PSalmonella spp. population by 2.30 log CFU/cm2 when compared with the initial surface attachment. Moreover, the combined treatment of LA 2.5% + phage 5% significantly (PSalmonella population by 2.35 log CFU/cm2 after 1 hour of attachment. In the post-tenderization surface samples, the combination of both phage and LA showed (PP>0.05) when analyzing the translocation of Salmonella spp. on pork loins.
Similar treatment efficacy results were observed in the application of E. coli O157:H7 on pork. Following antimicrobial treatments, both control and treated loin samples were enumerated after 1 h at 4°C. Both the lytic bacteriophage 5% and the combination of lytic bacteriophage 5% with lactic acid 2.5% had a significant reduction of E. coli O157:H7 on surface attachment after 1 h of treatment application. Lytic bacteriophage 5% and Lactic acid 2.5% significantly (P < 0.05) reduced the surface bacterial population by 1.89 log CFU/cm2. Lytic bacteriophage 5% alone significantly (P < 0.05) reduced the surface bacterial population by 1.90 log CFU/cm2 when compared with the initial surface attachment groups. Moreover, in the post-tenderization surface samples, lytic bacteriophage 5% and the combination of lytic bacteriophage 5% with lactic acid 2.5% were the only treatments that had a significant reduction (P < 0.05) when compared with the control group. Interestingly, lactic acid 2.5% was the only treatment that had a significant reduction (P < 0.05) of 0.76 log CFU/cm2 when analyzing the translocation of pathogens on pork chops.