Abstract
Intramuscular color stability variations in beef semimembranosus have been reported previously. Mitochondria remain biochemically active in postmortem muscle and can influence fresh beef color stability. However, the role of mitochondrial functionality in intramuscular color variations in beef semimembranosus is yet to be examined. We examined the functionality of mitochondria isolated from outside (OSM) and inside (ISM) regions of beef semimembranosus. Semimembranosus muscles (n = 5) were collected from inside rounds of beef carcasses 48 h post-mortem and were separated to OSM and ISM steaks. Color attributes were evaluated instrumentally and biochemically on days 0 and 4 of retail display, whereas mitochondrial oxygen consumption rate (OCR) was measured on day 0 using succinate as substrate using steaks frozen during fabrication. Mitochondrial OCR was significantly greater in OSM than in ISM on day 0. The ISM steaks exhibited significantly greater redness (a* value) than OSM steaks on day 0, but OSM steaks had significantly greater redness than the ISM counterparts on day 4. During retail display, ISM steaks exhibited greater lightness (L* value) than OSM steaks. However, OSM demonstrated significantly greater color stability and metmyoglobin reducing activity than ISM throughout the display. The observed differences in mitochondrial OCR between ISM and OSM steaks indicated that mitochondrial biochemistry possibly contributes to the intramuscular color variations in beef semimembranosus.Keywords: Beef color, color stability, mitochondria, semimembranosus
Highlights
Fresh meat color critically influences consumer purchase decisions (Suman et al, 2014), and the annual revenue loss to the United States beef industry due to discoloration is estimated to be more than 1 billion USD (Smith et al, 2000)
The cuts were vacuum packaged in the plant and transported under refrigeration to the USDAinspected meat laboratory at University of Kentucky, where the semimembranosus muscle was separated and fabricated into 2.54 cm OSM and ISM steaks
Ψ oxygen consumption rate (OCR) measured as nanomoles of oxygen consumed per mg mitochondria per minute NA = not available
Summary
Fresh meat color critically influences consumer purchase decisions (Suman et al, 2014), and the annual revenue loss to the United States beef industry due to discoloration is estimated to be more than 1 billion USD (Smith et al, 2000). Beef color and color stability are muscle-specific traits (McKenna et al, 2005; Von Seggern et al, 2005). Large beef muscles such as semimembranosus (Sammel et al, 2002a) and biceps femoris (Pastsart et al, 2013) exhibit intramuscular variations in color stability. Beef semimembranosus can be separated into color-stable outside (OSM) and color-labile inside (ISM) regions based on the location within the carcass. The variation in color has been partly attributed to differences in temperature and pH decline during carcass chilling (Sammel et al, 2002a). Further research indicated that differential abundance of sarcoplasmic proteome could result in rapid pH fall and compromise color stability of ISM (Nair et al, 2016)
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