Thesis
The effects of high-pressure processing and nisin on Listeria growth, quality, and sensory characteristics of cold-smoked Pacific Sockeye salmon
Washington State University
Master of Science (MS), Washington State University
2017
Handle:
https://hdl.handle.net/2376/100589
Abstract
Cold-smoked salmon (CSS) production lacks a validated kill step for Listeria monocytogenes. Previous studies have shown Listeria spp. in CSS are reduced by the FDA approved bacteriocin, nisin, or ambient temperature high-pressure processing (HPP), although muscle discoloration is observed. The effects of nisin and low-temperature HPP effects on Listeria innocua growth (non-pathogenic surrogate for L. monocytogenes), duration of shelf life, and sensory characteristics of CSS were studied. Three lots of cold-smoked sockeye salmon (Oncorhynchus nerka) fillets with or without nisin (10 µg/g) were inoculated with a 3-strain L. innocua cocktail (6 Log CFU/g), vacuum-packaged, frozen, and placed in an ice-slurry bath within an insulated sleeve for HPP. Preliminary experiments evaluated L. innocua growth on CSS ± nisin after HPP at 450 MPa or 600 MPa for 30, 60, or 120 s and 7 °C storage for 36 days. Nisin and HPP for 120 s at 450 MPa (N+HPP450) and 600 MPa (N+HPP600) were selected for further studies. Listeria, psychrotrophs, lactic acid bacteria (LAB), and color of CSS were monitored during 36-day storage at 4 °C and 7 °C. Additionally, CSS appearance, aroma, texture, flavor, overall liking, and peelability were further evaluated on day 0. Listeria innocua in N+HPP450 and N+HPP600 was reduced by 2.63 and 3.99 Log CFU/g, respectively, with no growth of L. innocua during 36-day storage at 4 °C. Psychrotrophs and LAB in N+HPP450 and N+HPP600 were < 1 Log CFU/g on day 36. Low-temperature HPP increased lightness (L*) of CSS on day 0 by 3.21 and 3.61 units, although, ambient-temperature HPP performed in previous studies observed greater increases in lightness. Overall liking of N+HPP450 and N+HPP600 was preferred over the control by 61% and 62% of panelists, respectively (P = 0.0049, P = 0.0019, respectively). Peelability of sliced CSS was reduced after N+HPP450 and N+HPP600 (P = 0.0092, P = 0.0120, respectively), and may be improved by shingling slices in skin packaging. In summary, incorporation of nisin and low-temperature HPP into CSS production has potential to control Listeria growth while maintaining consumer acceptability.
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Details
- Title
- The effects of high-pressure processing and nisin on Listeria growth, quality, and sensory characteristics of cold-smoked Pacific Sockeye salmon
- Creators
- Noelle Kaitlin Lebow
- Contributors
- Denise M. Smith (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Food Science, School of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; [Pullman, Washington] :
- Identifiers
- 99900524805101842
- Language
- English
- Resource Type
- Thesis