AbstractBACKGROUNDHeat stress (HS) has an adverse effect on meat quality; however, the underlying molecular mechanisms altering meat quality due to muscle responses to stress remain unclear. Sixteen castrated male crossbreeds between Landrace × Yorkshire sows and Duroc boars (79.00 ± 1.50 kg body weight) were exposed to either thermal neutral (22 °C, n = 8) or HS (30 °C, n = 8) conditions for 3 weeks. Subsequently, the longissimus dorsi (LD) muscle of all pigs was assayed for meat quality parameters and proteome analysis.RESULTSHS decreased post mortem (24 h) pH and intramuscular fat, changed ultimate L*, a* and b* values and increased drip loss and shear force. Proteome analysis of the LD was conducted by two‐dimensional gel electrophoresis and mass spectrometry. A total of 23 differentially expressed proteins were identified, of which three were verified by western blotting analysis. The identified proteins were involved in six types of biological process: carbohydrate metabolism, myofibrillar and cytoskeleton structure, stress response, antioxidant and detoxification, calcium binding and cellular apoptosis. Interestingly, HS induced higher levels of heat shock protein, antioxidants and calcium binding proteins, which are involved in the mechanisms of defense and homeostasis.CONCLUSIONThe results indicate that HS‐induced changes in the expression of myofibrillar proteins, glucose and energy metabolism‐related proteins, heat shock protein and antioxidant enzymes might, at least partly, contribute to increase in meat tenderness. These findings will provide the foundation for developing future mitigating solutions and preventative therapies to reduce the detrimental effects of chronic HS on muscle function, metabolism and meat quality. © 2017 Society of Chemical Industry