Department of Nutrition and Food Science, Texas A&M University, College Station, TX, USA.
Department of Biological and Agricultural Engineering, Texas A&M University, College Station, TX, USA.
Int J Food Microbiol. 2019 Jan 16;289:57-63. doi: 10.1016/j.ijfoodmicro.2018.08.023. Epub 2018 Aug 23.
Several outbreaks of illness have been associated with consumption of alfalfa sprouts contaminated with Shiga toxin-producing Escherichia coli (STEC) and Salmonella. The ozone application was investigated as an intervention. Alfalfa seeds were inoculated with cocktails of 3 Salmonella strains, including serotypes Typhimurium, Agona and Saintpaul, and 3 strains of Shiga toxin-producing Escherichia coli (STEC) including serotypes O104:H4, O157:H7 and O121:H19 with a final load of 7.0 log CFU/ml. Then, the inoculated seeds, and the sprouts obtained from these seeds were separately subjected to aqueous ozone treatment containing (5 mg/L) ozone for varied times of exposure. The mean log reductions for Salmonella achieved on seeds after 10, 15, and 20 min of ozone exposure were 1.6 ± 0.5, 1.7 ± 0.3, 2.1 ± 0.5, respectively and 1.5 ± 0.4, 1.6 ± 0.4, 2.1 ± 0.5 for STEC, respectively. For sprouts obtained from the inoculated seed, the mean log reductions for Salmonella after 10, 15, and 20 min exposure times were 0.7 ± 0.2, 1.1 ± 0.4, 3.6 ± 0.2, respectively, whereas the mean log reductions for STEC were 0.7 ± 0.1, 1.2 ± 0.3 and 1.8 ± 0.2, respectively. At each contact time, there were no differences in log reductions between pathogens on seeds (P > 0.05), whereas on sprouts, the reductions obtained at 20 min were significantly greater (P < 0.05) for Salmonella than for STEC. On both seeds and sprouts, the exposure time had significant (P < 0.05) effects on log reductions of Salmonella and STEC. The weight, color properties and shelf life of ozonated sprouts were also tested. The ozonation did not have negative effects on germination (%), color and mass of sprouts in comparison with the controls. This study confirmed that it is possible to substantially reduce Salmonella and STEC by using a low ozone concentration (5 mg/L) and reduce food safety risk with less concern about the safety for processing workers of this treatment, this without affecting seed germination. This procedure may be a promising intervention to reduce Salmonella and STEC from alfalfa seeds and sprouts.
几种疾病的爆发与食用受产志贺毒素大肠埃希氏菌（STEC）和沙门氏菌污染的苜蓿芽有关。臭氧处理已被作为一种干预措施进行了研究。将苜蓿种子接种 3 种沙门氏菌株的混合物，包括肠炎沙门氏菌、阿贡纳沙门氏菌和圣保尔沙门氏菌，以及 3 株产志贺毒素大肠埃希氏菌（STEC）株，包括 O104：H4、O157：H7 和 O121：H19，最终负荷为 7.0log CFU/ml。然后，分别对接种种子和由这些种子获得的豆芽进行含（5mg/L）臭氧的水臭氧处理，暴露时间不同。在 10、15 和 20 分钟的臭氧暴露后，种子上沙门氏菌的平均对数减少分别为 1.6±0.5、1.7±0.3 和 2.1±0.5，而 STEC 的平均对数减少分别为 1.5±0.4、1.6±0.4 和 2.1±0.5。对于从接种种子中获得的豆芽，在 10、15 和 20 分钟暴露时间后，沙门氏菌的平均对数减少分别为 0.7±0.2、1.1±0.4 和 3.6±0.2，而 STEC 的平均对数减少分别为 0.7±0.1、1.2±0.3 和 1.8±0.2。在每个接触时间，病原体在种子上的对数减少无差异（P>0.05），而在豆芽上，20 分钟的减少明显大于 STEC（P<0.05）。在种子和豆芽上，暴露时间对沙门氏菌和 STEC 的对数减少均有显著影响（P<0.05）。臭氧处理对豆芽的发芽率（%）、颜色特性和货架期也进行了测试。与对照相比，臭氧处理对发芽率、颜色和豆芽质量没有产生负面影响。本研究证实，使用低浓度（5mg/L）臭氧可以大大减少沙门氏菌和 STEC，并且在处理过程中减少对工人安全的担忧，而不会影响种子发芽，从而降低食品安全风险。该程序可能是减少苜蓿种子和豆芽中沙门氏菌和 STEC 的一种有前景的干预措施。
