U.S. Food and Drug Administration, National Center for Food Safety and Technology, Summit-Argo, Illinois 60501, USA.
J Food Prot. 2009 Nov;72(11):2390-3. doi: 10.4315/0362-028x-72.11.2390.
Spinach leaves are frequently consumed raw and have been involved with past foodborne outbreaks. In this study, we examined the survival of hepatitis A virus (HAV) on fresh spinach leaves in moisture- and gas-permeable packages that were stored at 5.4 +/- 1.2 degrees C for up to 42 days. Different eluents including phosphate-buffered saline (PBS), pH 7.5 (with and without 2% serum), and 3% beef extract (pH 7.5 and 8) were compared for how efficiently they recovered viruses from spinach by using a simple elution procedure (<1 h). The recoveries were compared and determined by a plaque assay with FRhK-4 cells. Culture grade PBS containing 2% serum was found to be appropriate for HAV elution from spinach leaves, with an average recovery of 45% +/- 10%. Over 4 weeks of storage at 5.4 +/- 1.2 degrees C, HAV in spinach decreased slightly more than 1 log, with 6.75% of the original titer remaining. HAV survived under refrigerated temperatures on spinach leaves with a D-value of 28.6 days (equivalent to an inactivation rate of -0.035 log of HAV per day, r(2) = 0.88). In comparison, HAV in PBS containing 2% serum under the same storage conditions remained constant throughout 7 weeks. The inactivation rate of -0.035 log each day for HAV on spinach leaves was possibly due to the interaction of the virus and the leaf.
菠菜叶经常被生食，曾与过去的食源性疾病爆发有关。在这项研究中，我们研究了甲型肝炎病毒（HAV）在可透气和透湿的包装中保存在 5.4±1.2°C 下长达 42 天的存活情况。不同的洗脱液，包括磷酸盐缓冲盐水（PBS）、pH7.5（含或不含 2%血清）和 3%牛肉提取物（pH7.5 和 8），都通过简单的洗脱程序（<1 小时）来比较从菠菜中回收病毒的效率。采用 FRhK-4 细胞进行噬斑测定来比较和确定回收率。结果发现，含 2%血清的 PBS 是从菠菜叶中洗脱 HAV 的合适洗脱液，平均回收率为 45%±10%。在 5.4±1.2°C 的冷藏条件下储存超过 4 周，HAV 在菠菜中的含量略有下降，约为原始滴度的 6.75%。HAV 在冷藏温度下的菠菜叶上存活时间长达 28.6 天（相当于每天 HAV 的失活率为-0.035 log，r(2) = 0.88）。相比之下，在相同的储存条件下，含 2%血清的 PBS 中的 HAV 在 7 周内保持不变。HAV 在菠菜叶上的失活率为每天-0.035 log，可能是由于病毒与叶片之间的相互作用。
