Associations of Apoptotic and Anti-Apoptotic Factors with Beef Quality, Histochemical Characteristics, and Palatability of Hanwoo Longissimus thoracis Muscle

SIMPLE SUMMARY: After the onset of muscle fiber apoptosis, various apoptotic and anti-apoptotic factors are selectively increased. These factors are directly and/or indirectly associated with tenderness variation. Given the complex relationship between the apoptosis-related molecules, more data are needed on how the expression patterns of these factors during the post-mortem period affects the palatability of beef. In this study, the combination of expression levels of apoptotic (cytochrome c and caspases) and anti-apoptotic (small heat shock proteins) factors at 45 min post-mortem tended to be associated with Warner-Bratzler shear force and tenderness attributes in Hanwoo steers with a lower degree of marbling. Meanwhile, levels of these molecules at 24 h had a somewhat limited effect on the beef tenderness. Clearly, these results demonstrate that expression levels of apoptotic and anti-apoptotic molecules at the early post-mortem period may be a relevant indicator to explain the tenderness variation in Hanwoo. ABSTRACT: This study compared the meat quality, histochemical traits, palatability, and expression levels of apoptotic (cytochrome c and caspases) and anti-apoptotic (small heat shock proteins) factors at 45 min and 24 h post-mortem of Hanwoo Longissimus thoracis muscles in groups categorized by Warner-Bratzler shear force (WBS) values to investigate the association between beef tenderness variation and apoptosis-related molecules. There were no differences in marbling scores, meat quality traits, or histochemical characteristics among the WBS groups (p > 0.05) indicating no significant effect on the tenderness variation in the current study. On the other hand, the low group exhibited higher levels of apoptotic and anti-apoptotic factors (except for αβ-crystallin) at 45 min post-mortem compared to the high WBS group, resulting in higher scores of tenderness attributes (p < 0.05). However, the level of αβ-crystallin at 45 min post-mortem was lower in the low and medium WBS groups compared to the high WBS group (p < 0.0106). At 24 h post-mortem, no significant differences were observed in the expression levels of apoptosis-related factors among the WBS groups (p > 0.05) except for heat shock protein 27 (p < 0.05).