Effect of hydrostatic high-pressure treatment on proteins, lipids and nucleotides in chilled farmed salmon (Oncorhynchus kisutch) muscle

The effect of a previous hydrostatic high-pressure (HHP) treatment on hydrolysis, breakdown and aggregation events in chemical constituents of chilled farmed coho salmon (Oncorhynchus kisutch) was studied. Three different HHP conditions were applied (135 MPa-30 s; 170 MPa-30 s; 200 MPa-30 s; treatments T-1, T-2 and T-3, respectively) and compared to untreated fish for a 20-day chilled storage. Nucleotide degradation was important during the chilled storage in all kinds of samples; however, the K value did not afford differences related to previous pressure applied. HHP treatment led to an increased free fatty acid (FFA) formation (day 0 values); on the contrary, an inhibitory effect on FFA formation could be observed at the end of the storage (15-20 days) in T-3-treated fish as a result of microbial activity inhibition. A marked decrease in sarcoplasmic protein content was evident in samples corresponding to T-2 and T-3 treatments; the SDS-PAGE analysis of such protein fraction showed a partial loss of a band corresponding to 29 kDa. This band was excised, digested with trypsin, analysed by tandem mass spectrometry and identified as phosphoglycerate mutase.