Food Science and Technology Department, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA; Centro de Estudios en Alimentos Procesados (CEAP), Avenida San Miguel # 3425, Talca 3480137, Chile.
Food Science and Technology Department, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA.
J Food Prot. 2014 May;77(5):832-6. doi: 10.4315/0362-028X.JFP-13-441.
Listeria monocytogenes is a foodborne pathogen that represents a high risk for consumers because it can grow under refrigeration conditions and can also develop acid tolerance. Fresh blueberries are hand-picked, packed, and transported under refrigeration without receiving a microbial inactivation treatment. The aim of this work was to study the survival of L. monocytogenes in fresh highbush blueberries stored at 4 or 12 °C under different controlled atmosphere conditions, including air (control); 5% O2, 15% CO2, 80% N2 (controlled atmosphere storage [CAS]); or ozone gas (O3), 4 ppm at 4 °C or 2.5 ppm at 12 °C, at high relative humidity (90 to 95%) for a total of 10 days. Fresh blueberries inside a plastic clamshell were spot inoculated with the bacteria and were stored at 4 or 12 °C in isolated cabinets under air, CAS, and O3 atmospheric conditions. Samples were evaluated on days 0, 1, 4, 7, and 10 for microbial growth using modified Oxford agar. CAS did not delay or inhibit L. monocytogenes growth in fresh blueberries after 10 days. O3 achieved 3- and 2-log reductions when compared with air treatment at 4 and 12 °C, respectively. Low concentrations of O3 together with proper refrigeration temperature can ensure product safety throughout transportation. O3 is a strong antimicrobial that safely decomposes to oxygen and water without leaving residues and can be used as an alternative method to prevent bacterial growth during a long transport period.
单增李斯特菌是一种食源性病原体，对消费者构成高风险，因为它可以在冷藏条件下生长，并且还可以产生耐酸能力。新鲜蓝莓是手工采摘、包装和冷藏运输的，在运输过程中不会进行微生物灭活处理。本研究旨在研究 4℃或 12℃下不同控制气氛条件下（包括空气[对照]；5%O2、15%CO2、80%N2[控制气氛储存（CAS）]；或臭氧气体[O3]，4 ppm 在 4℃或 2.5 ppm 在 12℃，高相对湿度（90%至 95%）下储存 10 天），新鲜蓝莓中李斯特菌的存活情况。新鲜蓝莓在塑料蛤壳内用细菌点接种，并在空气、CAS 和 O3 大气条件下在独立的柜子中在 4℃或 12℃下储存。在第 0、1、4、7 和 10 天，使用改良牛津琼脂评估微生物生长情况。在 10 天后，CAS 并没有延迟或抑制新鲜蓝莓中李斯特菌的生长。与空气处理相比，O3 在 4℃和 12℃时分别实现了 3 和 2 个对数减少。低浓度的 O3 与适当的冷藏温度相结合，可以确保产品在运输过程中的安全。O3 是一种强大的抗菌剂，它可以安全地分解为氧气和水，不会留下残留物，可作为防止细菌在长运输期间生长的替代方法。
