Yuk H G, Schneider K R
Food Science and Human Nutrition Department, University of Florida, P.O. Box 110370, Gainesville, Florida 32611-0370, USA.
Food Microbiol. 2006 Oct;23(7):694-700. doi: 10.1016/j.fm.2005.12.003. Epub 2006 Feb 10.
The objective of this study was to evaluate the acid resistance of Salmonella spp. adapted in juices stored under refrigeration and room temperatures to simulated gastric fluid (SGF, pH 1.5). Five Salmonella serovars, Agona, Gaminara, Michigan, Montevideo, and Poona were used in this study. Apple, orange, and tomato juices inoculated with five serovars were stored at refrigeration (7 degrees C) and room temperature (20 degrees C) for 24 h for adaptation. Acid resistances of serovars adapted in juice were determined in SGF at 37 degrees C. All acid-adapted Salmonella serovars in juices displayed enhanced survival time compared to non-adapted controls. Among serovars, S. Poona adapted in apple at 20 degrees C and orange juices at 7 and 20 degrees C showed >2.0 log cfu/ml survivors, while the other serovars decreased to non-detectable level or <2.0 log cfu/ml for 100 s in SGF. Unlike apple and orange juices, all serovars adapted in tomato juice survived with >2.0 log cfu/ml for 100 s. For D-values, all Salmonella serovars adapted in apple and tomato juice enhanced their acid resistances compared to orange juices. S. Agona adapted in tomato juice at 7 degrees C and S. Poona in apple juice at 20 degrees C had the highest D-values with 82.9 and 82.5s, respectively. Results showed that the adaptation in juice increased acid resistance in SGF and varied by serovar, juice type, and adaptation temperature. Therefore, this study indicates that the introduction of Salmonella spp. to an acidic juice environment during processing can enhance their ability to survive in a human stomach, possibly increasing the risk of a Salmonella outbreak by juice.
本研究的目的是评估在冷藏和室温下储存于果汁中的沙门氏菌对模拟胃液（SGF，pH 1.5）的耐酸性。本研究使用了五种沙门氏菌血清型，即阿哥纳、加米纳拉、密歇根、蒙得维的亚和普纳。接种了这五种血清型的苹果汁、橙汁和番茄汁分别在冷藏（7℃）和室温（20℃）下储存24小时以进行适应。在37℃的SGF中测定果汁中适应后的血清型的耐酸性。与未适应的对照相比，果汁中所有适应酸性环境的沙门氏菌血清型的存活时间均有所延长。在血清型中，在20℃苹果汁中适应的普纳沙门氏菌以及在7℃和20℃橙汁中适应的普纳沙门氏菌显示存活菌数>2.0 log cfu/ml，而其他血清型在SGF中100秒内降至检测不到的水平或<2.0 log cfu/ml。与苹果汁和橙汁不同，在番茄汁中适应的所有血清型在100秒内存活菌数>2.0 log cfu/ml。对于D值，与橙汁相比，在苹果汁和番茄汁中适应的所有沙门氏菌血清型的耐酸性均增强。在7℃番茄汁中适应的阿哥纳沙门氏菌以及在20℃苹果汁中适应的普纳沙门氏菌的D值最高，分别为82.9秒和82.5秒。结果表明，在果汁中的适应增加了在SGF中的耐酸性，并且因血清型、果汁类型和适应温度而异。因此，本研究表明，在加工过程中将沙门氏菌引入酸性果汁环境可增强其在人胃中的存活能力，可能增加因果汁引发沙门氏菌爆发的风险。
