Influence of High‐Pressure Processing at Low Temperature and Nisin on Listeria innocua Survival and Sensory Preference of Dry‐Cured Cold‐Smoked Salmon

Cold‐smoked salmon (CSS) production lacks a validated kill step for Listeria monocytogenes. Although Listeria spp. are reduced by nisin or high‐pressure processing (HPP), CSS muscle discoloration is often observed after HPP. Effects of nisin and low‐temperature HPP on L. innocua survival (nonpathogenic surrogate for L. monocytogenes), spoilage organism growth, color, and sensory preference and peelability of CSS were studied. Cold‐smoked sockeye salmon (Oncorhynchus nerka) fillets ± nisin (10 μg/g) were inoculated with a 3‐strain L. innocua cocktail, vacuum‐packaged, frozen at – 30 °C, and high‐pressure processed in an ice slurry within an insulated sleeve. Initial experiments indicated that nisin and HPP for 120 s at 450 MPa (N450) and 600 MPa (N600) were most effective against L. innocua, and thus were selected for further storage studies. L. innocua in N450 and N600‐treated CSS was reduced 2.63 ± 0.15 and 3.99 ± 0.34 Log CFU/g, respectively, immediately after HPP. L. innocua and spoilage growth were not observed in HPP‐treated CSS during 36 d storage at 4 °C. Low‐temperature HPP showed a smaller increase in lightness of CSS compared to ambient‐temperature HPP performed in previous studies. Sensory evaluation indicated that overall liking of CSS treated with N450 and N600 were preferred over the control by 61% and 62% of panelists, respectively (P < 0.05). Peelability of sliced CSS was reduced by HPP (P < 0.05). Nisin in combination with low‐temperature HPP was effective in controlling L. innocua in CSS while maintaining consumer acceptability. Practical Application Cold‐smoked salmon is a high‐risk ready‐to‐eat product that may be contaminated with L. monocytogenes. Results showed that nisin combined with high‐pressure processing at low temperature, reduced the population of Listeria and controlled the spoilage organisms during storage. As an added benefit, high‐pressure processing at low temperature may reduce lightening of the salmon flesh, leading to enhanced consumer preference.