Bovo Federica, De Cesare Alessandra, Manfreda Gerardo, Bach Susan, Delaquis Pascal
Department of Agricultural and Food Sciences, University of Bologna, Via del Florio 2, 40064 Ozzano dell'Emilia (BO), Italy.
Agriculture and Agri-Food Canada, Pacific Agri-Food Research Centre, 4200 Highway 97 South, Summerland, British Columbia, Canada V0H 1Z0.
J Food Prot. 2015 Mar;78(3):491-7. doi: 10.4315/0362-028X.JFP-14-187.
Food service and retail sectors offer consumers a variety of mixed ingredient salads that contain fresh-cut vegetables and other ingredients such as fruits, nuts, cereals, dairy products, cooked seafood, cooked meat, cured meats, or dairy products obtained from external suppliers. Little is known about the behavior of enteric bacterial pathogens in mixed ingredient salads. A model system was developed to examine the fate of Salmonella enterica (inoculum consisting of S. enterica serovars Agona, Typhimurium, Enteritidis, Brandenberg, and Kentucky) on the surface of romaine lettuce tissues incubated alone and in direct contact with Cheddar cheese or cooked chicken. S. enterica survived but did not grow on lettuce tissues incubated alone or in contact with Cheddar cheese for 6 days at either 6 or 14°C. In contrast, populations increased from 2.01 ± 0.22 to 9.26 ± 0.22 CFU/cm(2) when lettuce washed in water was incubated in contact with cooked chicken at 14°C. Populations on lettuce leaves were reduced to 1.28 ± 0.14 CFU/cm(2) by washing with a chlorine solution (70 ppm of free chlorine) but increased to 8.45 ± 0.22 CFU/cm(2) after 6 days at 14°C. Experimentation with a commercial product in which one third of the fresh-cut romaine lettuce was replaced with inoculated lettuce revealed that S. enterica populations increased by 4 log CFU/g during storage for 3 days at 14°C. These findings indicate that rapid growth of bacterial enteric pathogens may occur in mixed ingredient salads; therefore, strict temperature control during the manufacture, distribution, handling, and storage of these products is critical.
食品服务和零售行业为消费者提供了各种混合配料沙拉，这些沙拉包含鲜切蔬菜和其他配料，如水果、坚果、谷物、乳制品、熟海鲜、熟肉、腌肉或从外部供应商采购的乳制品。对于混合配料沙拉中肠道细菌病原体的行为了解甚少。开发了一个模型系统，以研究肠炎沙门氏菌（接种物由肠炎沙门氏菌血清型阿贡纳、鼠伤寒、肠炎、勃兰登堡和肯塔基组成）在单独培养以及与切达干酪或熟鸡肉直接接触的长叶莴苣组织表面的存活情况。肠炎沙门氏菌在单独培养的莴苣组织上或在6℃或14℃下与切达干酪接触6天均能存活但未生长。相比之下，当在14℃下将水洗后的莴苣与熟鸡肉接触培养时，菌量从2.01±0.22 CFU/cm²增加到9.26±0.22 CFU/cm²。用氯溶液（70 ppm游离氯）洗涤后，莴苣叶上的菌量降至1.28±0.14 CFU/cm²，但在14℃下放置6天后增加到8.45±0.22 CFU/cm²。用接种莴苣替换三分之一鲜切长叶莴苣的商业产品进行实验表明，在14℃下储存3天期间，肠炎沙门氏菌菌量增加了4 log CFU/g。这些发现表明，肠道细菌病原体可能在混合配料沙拉中快速生长；因此，在这些产品的生产、配送、处理和储存过程中严格控制温度至关重要。
