Meat and Muscle Biology (Jan 2024)

Differences in Spoilage Microflora Growth Kinetics Could Be Contributing to Beef Muscle-Specific Color Stability

  • Colton L. Smith,
  • Ifigenia Geornaras,
  • Jessica Metcalf,
  • Mahesh N. Nair,
  • Sara V Gonzalez

DOI
https://doi.org/10.22175/mmb.16915
Journal volume & issue
Vol. 8, no. 1

Abstract

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The role of microbial communities on beef color stability during retail display is not fully understood. Therefore, this study aimed to characterize the physiochemical properties and microbial communities of color-stable (longissimus lumborum [LL]) and color-labile (psoas major PM]) beef muscles during aerobic retail display. Paired USDA Select beef LL and PM (n=5) were collected and aged (at 2°C) for 14 d. These were fabricated into 2.54-cm-thick steaks, packaged aerobically, and subjected to 7 d of retail display. Samples were evaluated daily for visual and instrumental color, percent-age discoloration, water activity, pH, metmyoglobin reducing activity (MRA), and bacterial population levels using conventional culture-based methodologies. Additionally, 16S ribosomal RNA (rRNA) amplicon sequencing was performed to characterize microbial communities associated with the LL and PM steaks throughout storage. The percentage discoloration was greater (P<0.05) in PM than LL after 2 d of retail display. Color stability, measured by MRA, was lower (P<0.05) for PM compared with LL each day. Culture-based microbiological analysis revealed that bacterial populations of PM steaks either exhibited no lag phase or had a shorter lag phase than the populations on LL samples. By the end of the retail display, bacterial levels on PM steaks were 1.3 to 1.6 log CFU/cm2 higher (P<0.05) than those recovered from LL samples. The 16S rRNA gene sequencing showed no differences (P≥0.05) in the alpha or beta diversities for the microbial communities of PM and LL on the same display day. The results confirmed that PM steaks had less color stability and a faster increase in bacterial numbers compared with LL during display. These results suggest that when initial bacterial communities are similar, the differential growth kinetics of bacteria present on these 2 muscles could contribute to the difference in their color stabilities.

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