Hwang Cheng-An
Microbial Food Safety Research Unit, Eastern Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, 600 East Mermaid Lane, Wyndmoor, Pennsylvania 19038, USA.
J Food Prot. 2007 Oct;70(10):2321-8. doi: 10.4315/0362-028x-70.10.2321.
Smoked salmon can be contaminated with Listeria monocytogenes. It is important to identify the factors that are capable of controlling the growth of L. monocytogenes in smoked salmon so that control measures can be developed. The objective of this study was to determine the effect of salt, a smoke compound, storage temperature, and their interactions on L. monocytogenes in simulated smoked salmon. A six-strain mixture of L. monocytogenes (10(2) to 10(3) CFU/g) was inoculated into minced, cooked salmon containing 0 to 10% NaCl and 0 to 0.4% liquid smoke (0 to 34 ppm of phenol), and the samples were stored at temperatures from 0 to 25 degrees C. Lag-phase duration (LPD; hour), growth rate (GR; log CFU per hour), and maximum population density (MPD; log CFU per gram) of L. monocytogenes in salmon, as affected by the concentrations of salt and phenol, storage temperature, and their interactions, were analyzed. Results showed that L. monocytogenes was able to grow in salmon containing the concentrations of salt and phenol commonly found in smoked salmon at the prevailing storage temperatures. The growth of L. monocytogenes was affected significantly (P < 0.05) by salt, phenol, storage temperature, and their interactions. As expected, higher concentrations of salt or lower storage temperatures extended the LPD and reduced the GR. Higher concentrations of phenol extended the LPD of L. monocytogenes, particularly at lower storage temperatures. However, its effect on reducing the GR of L. monocytogenes was observed only at higher salt concentrations (>6%) at refrigerated and mild abuse temperatures (< 10 degrees C). The MPD, which generally reached 7 to 8 log CFU/g in salmon that supported L. monocytogenes growth, was not affected by the salt, phenol, and storage temperature. Two models were developed to describe the LPD and GR of L. monocytogenes in salmon containing 0 to 8% salt, 0 to 34 ppm of phenol, and storage temperatures of 4 to 25 degrees C. The data and models obtained from this study would be useful for estimating the behavior of L. monocytogenes in smoked salmon.
烟熏三文鱼可能会被单核细胞增生李斯特菌污染。识别能够控制烟熏三文鱼中单核细胞增生李斯特菌生长的因素很重要，这样才能制定控制措施。本研究的目的是确定盐、一种烟熏成分、储存温度及其相互作用对模拟烟熏三文鱼中单核细胞增生李斯特菌的影响。将单核细胞增生李斯特菌的六菌株混合物（10²至10³CFU/g）接种到含有0至10%氯化钠和0至0.4%液态烟熏剂（0至34ppm苯酚）的切碎熟三文鱼中，样品在0至25℃的温度下储存。分析了盐和苯酚浓度、储存温度及其相互作用对三文鱼中单核细胞增生李斯特菌的延滞期持续时间（LPD；小时）、生长速率（GR；每小时对数CFU）和最大种群密度（MPD；每克对数CFU）的影响。结果表明，在当前储存温度下，单核细胞增生李斯特菌能够在含有烟熏三文鱼中常见盐和苯酚浓度的三文鱼中生长。单核细胞增生李斯特菌的生长受到盐、苯酚、储存温度及其相互作用的显著影响（P<0.05）。正如预期的那样，较高浓度的盐或较低的储存温度延长了延滞期并降低了生长速率。较高浓度的苯酚延长了单核细胞增生李斯特菌的延滞期，特别是在较低的储存温度下。然而，仅在冷藏和轻度滥用温度（<10℃）下较高盐浓度（>6%）时才观察到其对降低单核细胞增生李斯特菌生长速率的影响。在支持单核细胞增生李斯特菌生长的三文鱼中，最大种群密度通常达到7至8 log CFU/g，不受盐、苯酚和储存温度的影响。建立了两个模型来描述单核细胞增生李斯特菌在含有0至8%盐、0至34ppm苯酚和4至25℃储存温度的三文鱼中的延滞期和生长速率。本研究获得的数据和模型将有助于估计单核细胞增生李斯特菌在烟熏三文鱼中的行为。
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