Mackey B M, Boogard E, Hayes C M, Baranyi J
BBSRC Institute of Food Research, Reading Laboratory, UK.
Int J Food Microbiol. 1994 Jun;22(4):227-37. doi: 10.1016/0168-1605(94)90174-0.
Concern has been expressed that the ability of heat-injured Listeria monocytogenes cells to resuscitate during refrigerated storage of food may lead to underestimation of their heat resistance. The recovery of heat-injured L. monocytogenes was therefore examined as a function of incubation temperature and composition of recovery medium. Heat-injured cells exhibited a broad optimum temperature for recovery centered around 20-25 degrees C. The best recovery medium of those tested was blood agar. Incubation of cells in broth or chicken slurry at 5 degrees C (cold-enrichment) did not allow repair of potentially lethal injury i.e. it did not allow recovery of cells that would otherwise have died if incubated at a higher temperature. In some cases incubation of heat-injured cells at 5 degrees C resulted in death of a proportion of the population. Repair of sublethal heat-injury, measured as the time of incubation in tryptone soya broth needed to regain the ability to grow on Listeria selective agar, was slower and less complete at 25 degrees C than at 2 degrees C; repair took 10-15 h at 25 degrees C compared with 8-12 days at 5 degrees C. Refrigeration of heat-treated foods should not therefore increase the risk that heat-injured cells will recover from the heat treatment.
有人担心，热损伤的单核细胞增生李斯特菌细胞在食品冷藏储存期间复苏的能力可能导致对其耐热性的低估。因此，研究了热损伤的单核细胞增生李斯特菌的复苏情况与培养温度和复苏培养基成分的关系。热损伤细胞在20-25摄氏度左右呈现出较宽的最佳复苏温度。所测试的最佳复苏培养基是血琼脂。将细胞在肉汤或鸡肉泥中于5摄氏度下培养（冷增菌）不能修复潜在的致命损伤，即不能使那些在较高温度下培养否则会死亡的细胞复苏。在某些情况下，将热损伤细胞在5摄氏度下培养会导致一部分细胞死亡。以在胰蛋白胨大豆肉汤中培养以恢复在李斯特菌选择性琼脂上生长能力所需的时间来衡量，亚致死热损伤的修复在25摄氏度下比在2摄氏度下更慢且更不完全；在25摄氏度下修复需要10-15小时，而在5摄氏度下需要8-12天。因此，热处理食品的冷藏不应增加热损伤细胞从热处理中复苏的风险。
