Label-Free Proteomics of Tilapia Fillets and Their Relationship with Meat Texture During Post-Mortem Storage

Here, we aimed to study the changes in proteome of tilapia during post-mortem storage. The effects of post-mortem storage time (0 and 7days in ice storage) on the proteome of tilapia skeletal muscle was characterized by label-free proteomics. In total, 902 proteins were identified, of which 34 proteins underwent alterations that were statistically significant (P<0.05). The 15 up-regulated and 19 down-regulated proteins were mainly structural proteins, followed by transcription and translation regulation, enzymes, and stress proteins. The top three enriched Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways are metabolic pathways, tight junction, and ribosome. Two differentially abundant proteins, pgm1 and ldha, were selected for further verification using 0- and 7-day iced storage fish muscle. Western blotting analysis showed significantly lower levels of two proteins, ldha and pgm1, in ice-stored tilapia fillets than in fresh tilapia fillets. Our results indicate that meat tenderness is related to structural protein degradation and increased levels of lactic acid caused by enzymes and anaerobic conditions and provide an important basis toward enabling further understanding of the molecular mechanisms responsible for differences in fish texture and meat tenderness between fresh and ice-stored fish.