Rodgers Stephanie L, Ryser Elliot T
Department of Food Science and Human Nutrition, 2108 South Anthony Hall, Michigan State University, East Lansing, Michigan 48824-1224, USA.
J Food Prot. 2004 Apr;67(4):767-71.
Sodium hypochlorite (100 ppm), copper ion water (1 ppm), and sonication (22 to 44 kHz and 44 to 48 kHz) were assessed individually and in combination for their ability to reduce populations of Escherichia coli O157:H7 and Listeria monocytogenes on apples and in apple cider. Commercial unpasteurized cider was inoculated to contain approximately 10(6) CFU/ml of either pathogen and then sonicated at 44 to 48 kHz, with aliquots removed at intervals of 30 to 60 s for up to 5 min and plated to determine numbers of survivors. Subsequently, whole apples were inoculated by dipping to contain approximately 10(6) CFU/g E. coli O157:H7 or L. monocytogenes, held overnight, and then submerged in 1 ppm copper ion water with or without 100 ppm sodium hypochlorite for 3 min with or without sonication at 22 to 44 kHz and examined for survivors. Treated apples were also juiced, with the resulting cider sonicated for 3 min. Populations of both pathogens decreased 1 to 2 log CFU/ml in inoculated cider following 3 min of sonication. Copper ion water alone did not significantly reduce populations of either pathogen on inoculated apples. However, when used in combination with sodium hypochlorite, pathogen levels decreased approximately 2.3 log CFU/g on apples. Sonication of this copper ion-sodium hypochlorite solution at 22 to 44 kHz did not further improve pathogen reduction on apples. Numbers of either pathogen in the juice fraction were approximately 1.2 log CFU/ml lower after being juiced, with sonication (44 to 48 kHz) of the expressed juice decreasing L. monocytogenes and E. coli O157:H7 populations an additional 2 log. Hence, a 5-log reduction was achievable for both pathogens with the use of copper ion water in combination with sodium hypochlorite followed by juicing and sonication at 44 to 48 kHz.
分别评估了次氯酸钠（100 ppm）、铜离子水（1 ppm）以及超声处理（22至44千赫兹和44至48千赫兹）单独使用和联合使用时，减少苹果及苹果汁中大肠杆菌O157:H7和单核细胞增生李斯特菌数量的能力。将市售未巴氏杀菌的苹果汁接种，使其含有大约10⁶CFU/ml的任一种病原体，然后在44至48千赫兹下进行超声处理，每隔30至60秒取出等分试样，持续5分钟，之后进行平板接种以确定存活菌数。随后，将整个苹果通过浸泡接种，使其含有大约10⁶CFU/g的大肠杆菌O157:H7或单核细胞增生李斯特菌，放置过夜，然后浸入含有或不含有100 ppm次氯酸钠的1 ppm铜离子水中3分钟，同时进行或不进行22至44千赫兹的超声处理，并检查存活情况。对接种后的苹果进行榨汁，所得苹果汁再进行3分钟的超声处理。超声处理3分钟后，接种苹果汁中两种病原体的数量均下降了1至2个对数CFU/ml。单独使用铜离子水并不能显著减少接种苹果上任何一种病原体的数量。然而，当与次氯酸钠联合使用时，苹果上病原体水平下降了约2.3个对数CFU/g。在22至44千赫兹下对这种铜离子 - 次氯酸钠溶液进行超声处理，并未进一步提高苹果上病原体的减少量。榨汁后，果汁部分中任一种病原体的数量大约降低1.2个对数CFU/ml，对挤出的果汁进行超声处理（44至48千赫兹）可使单核细胞增生李斯特菌和大肠杆菌O157:H7的数量再减少2个对数。因此，通过联合使用铜离子水和次氯酸钠，随后进行榨汁以及在44至48千赫兹下进行超声处理，两种病原体均可实现5个对数的减少。
