Novel indicators of DFD beef: oxidative stress, autophagy and apoptosis

In cattle, pre-slaughter stress causes the appearance of DFD (Dark, Firm, Dry) beef, with defective postmortem muscle pH decline and detrimental quality that reduce its commercial value. This paper aims to study differences in oxidative stress, cell survival or death mechanisms (autophagy/apoptosis) and proteomic biomarkers at 24 h post-mortem between beef carcasses with normal pH decline (pH = 5.4-5.8 at 24 h post-mortem) used as CONTROL and carcasses with pH at 24 h hours post-mortem (pH(24)) > 6.0 classified as DFD, in order to understand the relevant changes on the early post-mortem muscle metabolism related to the DFD occurrence. Cell oxidative stress was analyzed as total antioxidant activity and damage of macromolecules (proteins and lipids). The results showed that DFD meat had increased muscle antioxidant activity (P < 0.05) as well as increased protein damage (P < 0.05). In addition, biomarkers of autophagy (Beclin-1 and LC3-II/LC3-I) and apoptosis (caspase-3), and changes of the muscle proteome were analyzed. The results showed the coexistence of autophagy and apoptosis in the muscle tissue at 24 h post-mortem, but with differential expression (P < 0.05), which allows to discriminate between DFD and CONTROL beef.