Effect of high-pressure treatment on microbial activity and lipid oxidation in chilled coho salmon

Abstract

This work studies the effect of a previous hydrostatic high-pressure (HHP) treatment on chilled farmed coho salmon (Oncorhynchus kisutch). Three different HHP conditions were applied (135 MPa-30 s, 170 MPa-30 s, and 200 MPa-30 s for treatments T-1, T-2, and T-3, respectively) and compared to untreated (control) fish throughout a 20-day chilled storage. Microbial activity and lipid oxidation development were analyzed. Assessment of aerobe, psychrotroph, Shewanella spp. and Pseudomonas spp. counts and trimethylamine formation showed a marked inhibitory effect (p ,0.05) of HHP treatment on microbial activity, with this effect increasing with the pressure value employed. Related to lipid oxidation development, higher peroxide mean values (day 10–20 period) were found in control samples and fish treated under T-1 condition when compared to their counterparts corresponding to T-2 and T-3 treatments. On the contrary, quantification of thiobarbituric acid-reactive substances and fluorescent interaction compounds showed higher levels (p ,0.05) in fish samples corresponding to T-2 and T-3 treatments. In spite of the lipid oxidation development found, polyene index and tocopherol isomer (a and g) content did not provide differences (p .0.05) as a result of previous HHP treatment.