Influence of Muscle Fiber Direction on Migration of Salmonella Enteritidis, Staphylococcus aureus, and Escherichia coli into Raw Chicken Breast

Abstract

The influence of muscle fiber direction (parallel or perpendicular) in relation to the inoculation surface on migration of Salmonella Enteritidis, Staphylococcus aureus, and Escherichia coli into raw chicken breasts was examined. Chicken breast samples with two types of surface fibers (running parallel or perpendicular to the surface) were inoculated with cultures of each bacterium. Inoculated samples were stored for 5 min, 1 h, or 24 h at 4°C. After storage, the samples were divided into segments, and bacterial counts were determined in different regions (inoculation surface, inoculation surface to 1 cm, 1 to 2 cm, 2 to 4 cm, and 4 to 6 cm). The migration of bacteria did not change at 5 min or 1 h regardless of fiber direction. However, after 24 h each bacterium was detected at 4 to 6 cm in the pieces of sample with a perpendicular muscle fiber surface cut. Although these bacteria were detected at 4 to 6 cm in samples with muscle fibers perpendicular to the inoculated surface, these results do not clearly indicate that bacteria migrated into the chicken breast. To monitor actual migration of bacteria into the chicken breast, the tops of the perpendicular muscle fibers of the breast sample were inoculated with bioluminescent E. coli Xen-14. Various regions of the breast sample (inoculation surface and cut surfaces at 1, 2, 4, and 6 cm) were stamped directly on growth medium. Culture revealed that the bacteria migrated directly under the contaminated site and dispersed along the surface of the chicken breast segments. More bacteria distributed laterally than migrated directly below the contamination site. These results suggest that the direction of the muscle fibers is a major factor influencing migration of pathogenic bacteria into chicken breast. HIGHLIGHTS

Spoilage‐related microbiota in fish and crustaceans during storage: Research progress and future trends

“…In a model system used colloidal particles to simulate nonmotile bacteria, the addition of protease also accelerated particle migration in pork (Bosse, Gibis, Schmidt, & Weiss, 2015). Besides, the penetration and migration of bacteria in meat systems can be also influenced by other factors (e.g., storage temperatures, the direction of muscle fibers, and human processing like mechanical curing) (Bosse, Thiermann, Gibis, Schmidt, & Weiss, 2017; Shimamura et al., 2020; Tozzo et al., 2018). In comparison with the detection of bacteria in different meat depth, recent studies tended to adopt model systems (e.g., using colloidal particles to simulate bacteria), mathematical simulation, and novel imaging technologies (e.g., confocal scanning laser microscopy) to analyze the bacterial migration process in meat (Bosse et al., 2015, , 2017; Shirai, Datta, & Oshita, 2017).…”