Reina L D, Fleming H P, Humphries E G
Department of Food Science, North Carolina State University, Raleigh, North Carolina 27695-7624.
Food Fermentation Laboratory, U. S. Department of Agriculture, Agricultural Research Service, and North Carolina Agricultural Research Service.
J Food Prot. 1995 May;58(5):541-546. doi: 10.4315/0362-028X-58.5.541.
The time required to cool size 2B (3.43 to 3.75-cm-diameter) pickling cucumbers by a commercial spray-type hydrocooler to less than 9°C was about 18 min at typical initial fruit temperatures of 25 to 29°C. During this period, the fruit was exposed to the recycled water, which reached relatively high populations of bacteria (10 to 10 colony forming unites [CFU]/g total aerobes and 10 to 10 CFU/g total Enterobacteriaceae) during a typical day's operation. These numbers exceeded those present on the unwashed fruit, depending upon the volume of fruit previously cooled. Residual chlorine dioxide at 1.3 ppm was found to optimally control (2 to 6 log-cycles reduction) the numbers of bacteria. At 0.95 ppm chlorine dioxide, the numbers of bacteria in the water were relatively static, while at 2.8 and 5.1 ppm the odor of chlorine dioxide became excessive. The bacterial populations in/on the cucumbers were not greatly influenced by chlorine dioxide, even at 5.1 ppm. Apparently, microorganisms on or in the fruit were protected from the chlorine dioxide. Thus, the use of chlorine dioxide in hydrocooling water of cucumbers seems to be an effective means of controlling microbial build-up in the water, but has little effect upon microorganisms on or in the fruit.
在典型的初始果实温度为25至29°C的情况下，一台商用喷雾式水冷器将2B尺寸（直径3.43至3.75厘米）的腌制黄瓜冷却至9°C以下所需的时间约为18分钟。在此期间，果实暴露于循环水中，在典型的一天运行过程中，循环水中细菌数量相对较高（总需氧菌为10⁵至10⁷菌落形成单位[CFU]/克，总肠杆菌科为10⁴至10⁶CFU/克）。这些数量超过了未清洗果实上的细菌数量，这取决于之前冷却的果实量。发现1.3 ppm的残留二氧化氯能最佳地控制（减少2至6个对数周期）细菌数量。在0.95 ppm二氧化氯时，水中细菌数量相对稳定，而在2.8 ppm和5.1 ppm时，二氧化氯气味变得过大。即使在5.1 ppm时，黄瓜上/内的细菌数量也没有受到二氧化氯的太大影响。显然，果实上或果实内的微生物受到了二氧化氯的保护。因此，在黄瓜水冷中使用二氧化氯似乎是控制水中微生物滋生的有效手段，但对果实上或果实内的微生物几乎没有影响。
