Microbial Profile Evaluation of Beef Steaks From Different Packaging and Retail Lighting Display Conditions

Abstract

To date, meat microbiology research has relied on culture-dependent methods. Amplicon sequencing technology provides a deeper look into the microbial community. This study set out to evaluate the bacterial community of fresh beef longissimus lumborum steaks exposed to retail packaging and display conditions. Four packaging treatments were assigned after fabrication 7 d postmortem: high-oxygen modified atmosphere packaging, overwrapped packages within a carbon monoxide tri-gas flushed motherbag, vacuum rollstock pouches, and traditional overwrap. After a 14-d dark storage, carbon monoxide motherbag overwrapped packages were removed from the motherbag, and packages were distributed to a retail lighting condition for 72 h of retail display: fluorescent, light emitting diode, or darkness. Aerobic plate count and psychrotrophic bacteria were enumerated, in addition to 16S ribosomal RNA sequencing of DNA for microbial profile investigation. Sampling occurred at fabrication (7 d), end of dark storage (20 d), and end of retail display (23 d). The V3–V4 regions of the 16S bacterial ribosomal RNA gene were sequenced using the Illumina MiSeq platform (Illumina, San Diego, CA). Counts for aerobic plate count bacteria differed by packaging (P = 0.039) but not lighting (P > 0.05). Firmicutes and Proteobacteria were the dominate phyla identified but were not affected by packaging or lighting (P > 0.05). Traditional overwrapped packages displayed in darkness and fluorescence had a higher abundance of Carnobacterium compared with those displayed under light emitting diode (P = 0.05). Dark-stored samples had more Pseudomonas compared with fluorescent display, regardless of packaging type (P = 0.03). While packaging and lighting conditions had a minimal impact on the community composition, these data positively contribute to a baseline establishing bacterial community profiles of fresh beef steaks subjected to retail display. This foundation suggests that further work is needed to understand whether shifts are more likely to occur during extended shelf life or in other retail beef display conditions.