Nofima AS - Norwegian Institute of Food, Fisheries and Aquaculture Research, P. O. Box 210, N-1431, Ås, Norway.
Nofima AS - Norwegian Institute of Food, Fisheries and Aquaculture Research, P. O. Box 210, N-1431, Ås, Norway; Faculty of Science and Technology, Norwegian University of Life Sciences, P.O. Box 5003, N-1432 Ås, Norway.
Int J Food Microbiol. 2019 Feb 16;291:48-58. doi: 10.1016/j.ijfoodmicro.2018.10.026. Epub 2018 Nov 1.
Contamination, survival and growth of Listeria monocytogenes in cold-smoked salmon represent serious health hazards to consumers and major challenges for salmon processors. Verdad N6, a commercially available buffered vinegar, was evaluated as an ingredient in cold-smoked salmon with regard to anti-listerial effects under processing and storage, sensory quality and consumer preference, effects on background microbiota and yield during production. Cold-smoked salmon with Verdad N6 added in the dry-salting process was produced. Salmon fillets were surface contaminated with a mix of L. monocytogenes. Levels of L. monocytogenes were determined during vacuum pack refrigerated storage for 29 days. The use of Verdad N6 resulted in increased lag times and reduced growth rates of L. monocytogenes. The inhibitory effects were dependent on Verdad N6 levels (0-2%), storage time and temperature (4 or 8 °C), type of contamination (between slices or on non-sliced salmon) and degree of smoking. The presence of dextrose (1%) in the recipe had no significant effects on L. monocytogenes levels after storage. On sliced salmon, complete growth inhibition at 4 °C storage could be obtained using 1% Verdad N6 compared to a 3 log increase in L. monocytogenes counts in control salmon. At abuse temperatures (8 °C), corresponding L. monocytogenes levels increased <2 log and 5-6 log during 29 days storage. On non-sliced salmon, 1% Verdad N6 provided complete growth reductions at 4 and 8 °C storage while L. monocytogenes in control salmon increased 2.3 and 4.6 log, respectively, in the same period. The use of Verdad N6 in combination with bactericidal UV-C treatments (fluence 50 mJ/cm) provided an initial 0.8 log reduction and complete L. monocytogenes growth inhibition on subsequent storage at 4 and 8 °C. Salmon with Verdad N6 showed reduced levels of total counts during storage and a shift in the dominating bacteria with reduced and increased relative levels of Photobacterium and lactic acid bacteria, respectively. A consumer test showed no consistent differences in liking of salmon with and without Verdad N6. In summary, Verdad N6 is an option for the production of high quality cold-smoked salmon with enhanced food safety through its robust listeriostatic effects. The application of Verdad N6 in combination with listericidal UV-C light treatment can further reduce the listeria-risks of this ready-to-eat food product category.
在烟熏三文鱼中，李斯特菌的污染、存活和生长对消费者的健康构成严重威胁，也是三文鱼加工商面临的主要挑战。Verdad N6 是一种市售的缓冲醋，本研究评估了其作为烟熏三文鱼加工和贮藏过程中的抗李斯特菌成分的效果，包括感官质量和消费者偏好、对背景微生物群的影响以及生产过程中的产量。通过在干盐腌制过程中添加 Verdad N6 生产烟熏三文鱼。三文鱼鱼片表面受到李斯特菌混合物的污染。在真空包装冷藏 29 天期间，测定了李斯特菌的水平。使用 Verdad N6 会导致李斯特菌的延迟期延长和生长速度降低。抑制效果取决于 Verdad N6 水平（0-2%）、贮藏时间和温度（4 或 8°C）、污染类型（切片之间或未切片三文鱼上）和烟熏程度。配方中添加 1%葡萄糖对贮藏后的李斯特菌水平没有显著影响。在切片三文鱼上，与对照三文鱼中李斯特菌计数增加 3 个对数级相比，4°C 贮藏时使用 1% Verdad N6 可完全抑制生长。在滥用温度（8°C）下，29 天贮藏期间李斯特菌水平分别增加<2 个对数级和 5-6 个对数级。在未切片三文鱼上，4 和 8°C 贮藏时，1% Verdad N6 完全抑制了李斯特菌的生长，而对照三文鱼中李斯特菌分别增加了 2.3 和 4.6 个对数级。Verdad N6 与杀菌紫外线-C 处理（剂量 50mJ/cm）联合使用可提供初始 0.8 个对数级的减少，并在随后的 4 和 8°C 贮藏中完全抑制李斯特菌的生长。在贮藏过程中，添加 Verdad N6 的三文鱼总计数水平降低，占主导地位的细菌发生变化，分别减少和增加 Photobacterium 和乳酸菌的相对水平。消费者测试表明，添加和不添加 Verdad N6 的三文鱼在喜好方面没有一致差异。总之，Verdad N6 是生产高质量烟熏三文鱼的一种选择，通过其强大的抑菌作用提高了食品安全。Verdad N6 的应用与杀菌紫外线-C 光处理相结合，可进一步降低此类即食食品的李斯特菌风险。
