Department of Animal and Food Sciences, University of Delaware, Newark, DE 19716-2150, USA.
Int J Food Microbiol. 2010 Jan 1;136(3):326-31. doi: 10.1016/j.ijfoodmicro.2009.10.003. Epub 2009 Oct 13.
The relatively high incidence of Listeria monocytogenes in cold smoked salmon (CSS) is of concern as CSS is a ready-to-eat product. No post-processing measures are currently available to control this pathogen in CSS. The objective of this study was to develop an effective antimicrobial edible coating containing organic salts to control the growth of L. monocytogenes in CSS slices and fillets. An in-house made formulation consisting of sodium lactate (SL, 0-2.4%) and sodium diacetate (SD, 0-0.25%) as well as 2.5% OptiForm (a commercial formulation of SL and SD) were incorporated into five edible coatings: alginate, kappa-carrageenan, pectin, gelatin or starch. The coatings were applied onto the surface of CSS slices inoculated with L. monocytogenes to an inoculum level of 500 CFU/cm(2) ( approximately 3 log CFU/g) and stored at room temperature (22 degrees C) for 6 days. Alginate coating was found to be the most effective carrier for the various antimicrobial treatments in inhibiting the growth of L. monocytogenes. In the second phase of the study, CSS slices and fillets inoculated with the pathogen at a level of 500 CFU/cm(2) were coated with alginate incorporating the in-house made and the commercial (OptiForm) SL/SD based formulations and stored for 30 days at 4 degrees C. When cold-smoked salmon slices and fillets were stored at 4 degrees C, alginate coatings supplemented with 2.4%SL/0.25%SD and the commercial product OptiForm significantly delayed the growth of L. monocytogenes during the 30-day storage with final counts reaching 4.1 and 3.3 log CFU/g (slices) and 4.4 and 3.8 log CFU/g (fillets), respectively, while the counts in their untreated counterparts were significantly higher (P<0.05) reaching 7.3 and 6.8 log CFU/g for slices and fillets, respectively. Therefore, this study demonstrates the effectiveness of using an alginate-based coating containing lactate and diacetate to control the growth of L. monocytogenes to enhance the microbiological safety of filleted and sliced smoked salmon.
生的烟熏三文鱼（CSS）中李斯特菌的相对高发率令人担忧，因为 CSS 是一种即食产品。目前没有后处理措施可用于控制 CSS 中的这种病原体。本研究的目的是开发一种有效的含有机盐的抗菌可食用涂层，以控制 CSS 切片和鱼片中生李斯特菌的生长。一种由乳酸钠（SL，0-2.4%）和双乙酸钠（SD，0-0.25%）以及 2.5%OptiForm（SL 和 SD 的商业配方）组成的内部配方被纳入五种可食用涂层中：藻酸盐、角叉菜胶、果胶、明胶或淀粉。将这些涂层涂在接种了李斯特菌的 CSS 切片表面，接种水平为 500 CFU/cm²（约 3 对数 CFU/g），在室温（22°C）下储存 6 天。藻酸盐涂层被发现是各种抗菌处理中最有效的载体，可抑制李斯特菌的生长。在研究的第二阶段，将在 500 CFU/cm²水平上接种病原体的 CSS 切片和鱼片用含有内部配方和商业（OptiForm）SL/SD 配方的藻酸盐进行涂层处理，并在 4°C 下储存 30 天。当冷熏三文鱼切片和鱼片在 4°C 下储存时，补充了 2.4%SL/0.25%SD 和商业产品 OptiForm 的藻酸盐涂层在 30 天的储存过程中显著延迟了李斯特菌的生长，最终计数分别达到 4.1 和 3.3 对数 CFU/g（切片）和 4.4 和 3.8 对数 CFU/g（鱼片），而未处理的对照物的计数明显更高（P<0.05），分别达到 7.3 和 6.8 对数 CFU/g 用于切片和鱼片。因此，本研究证明了使用含乳酸盐和双乙酸盐的藻酸盐基涂层来控制李斯特菌生长以提高鱼片和切片熏三文鱼的微生物安全性的有效性。
