Neetoo Hudaa, Ye Mu, Chen Haiqiang, Joerger Rolf D, Hicks Doris T, Hoover Dallas G
Department of Animal & Food Sciences, University of Delaware, Newark, DE 19716-2150, United States.
Int J Food Microbiol. 2008 Feb 29;122(1-2):8-15. doi: 10.1016/j.ijfoodmicro.2007.11.043. Epub 2007 Nov 21.
Cold-smoked (Salmo salar) salmon samples were surface-inoculated with a cocktail of three nisin-resistant strains of L. monocytogenes (PSU1, PSU2 and PSU21) to a level of approximately 5 x 10(2) or 5 x 10(5) CFU/cm2 of salmon surface. The inoculated smoked salmon samples were vacuum-packaged with control film (no nisin) or nisin-coated plastic films and stored at either 4 or 10 degrees C. When the inoculated smoked salmon samples were packaged with film coated with 2000 IU/cm2 of nisin, a reduction of 3.9 log CFU/cm2 (compared with control) was achieved at either temperature for samples inoculated with 5 x 10(2) CFU/cm(2 of L. monocytogenes after 56 (4 degrees C) and 49 (10 degrees C) days of storage while reductions of 2.4 and 0.7 log CFU/cm2 were achieved for samples inoculated with a high level of L. monocytogenes (5 x 10(5) CFU/cm2) after 58 (4 degrees C) and 43 (10 degrees C) days, respectively. For samples packaged in film coated with 500 IU/cm2 of nisin, reductions of 0.5 and 1.7 log CFU/cm2 were achieved for samples inoculated with a low level of L. monocytogenes (5 x 10(2) CFU/cm2) after 56 (4 degrees C) and 49 (10 degrees C) days of storage while reductions of 1.8 and 0.8 log CFU/cm2 were achieved for samples inoculated with high level of L. monocytogenes after 58(4 degrees C) and 43 (10 degrees C) days, respectively. In addition, nisin inhibited the proliferation of background microbiota on smoked salmon in a concentration-dependent manner at both storage temperatures although the bacteriostatic effect was more pronounced at refrigeration temperature. This work highlights the potential for incorporating nisin into plastic films for enhancing the microbial safety of smoked salmon as well as controlling its microbial spoilage.
将冷熏(大西洋鲑)三文鱼样本表面接种三种耐乳链菌肽的单核细胞增生李斯特菌菌株(PSU1、PSU2和PSU21)的混合菌液,使三文鱼表面达到约5×10²或5×10⁵CFU/cm²的接种水平。将接种后的烟熏三文鱼样本用对照薄膜(不含乳链菌肽)或涂有乳链菌肽的塑料薄膜进行真空包装,并分别储存在4℃或10℃下。当接种后的烟熏三文鱼样本用涂有2000 IU/cm²乳链菌肽的薄膜包装时,接种5×10²CFU/cm²单核细胞增生李斯特菌的样本在4℃储存56天和10℃储存49天后,每平方厘米菌落形成单位(CFU)数量减少了3.9个对数(与对照相比);而接种高水平单核细胞增生李斯特菌(5×10⁵CFU/cm²)的样本在4℃储存58天和10℃储存43天后,每平方厘米菌落形成单位数量分别减少了2.4个和0.7个对数。对于用涂有500 IU/cm²乳链菌肽的薄膜包装的样本,接种低水平单核细胞增生李斯特菌(5×10²CFU/cm²)的样本在4℃储存56天和10℃储存49天后,每平方厘米菌落形成单位数量分别减少了0.5个和1.7个对数;而接种高水平单核细胞增生李斯特菌的样本在4℃储存58天和10℃储存43天后,每平方厘米菌落形成单位数量分别减少了1.8个和0.8个对数。此外,在两个储存温度下,乳链菌肽均以浓度依赖的方式抑制烟熏三文鱼上背景微生物群的增殖,尽管抑菌作用在冷藏温度下更为明显。这项工作突出了将乳链菌肽掺入塑料薄膜以提高烟熏三文鱼微生物安全性以及控制其微生物腐败的潜力。