Department of Applied Chemistry and Microbiology, 00014 University of Helsinki, Helsinki, Finland.
J Food Prot. 2009 Nov;72(11):2236-42. doi: 10.4315/0362-028x-72.11.2236.
Food packaging papers are not sterile, as the manufacturing is an open process, and the raw materials contain bacteria. We modeled the potential transfer of the Bacillus cereus spores from packaging paper to food by using a green fluorescent protein-expressing construct of Bacillus thuringiensis Bt 407Cry(-) [pHT315Omega(papha3-gfp)], abbreviated BT-1. Paper (260 g m(-2)) containing BT-1 was manufactured with equipment that allowed fiber formation similar to that of full-scale manufactured paper. BT-1 adhered to pulp during papermaking and survived similar to an authentic B. cereus. Rice and chocolate were exposed to the BT-1-containing paper for 10 or 30 days at 40 or 20 degrees C at relative air humidity of 10 to 60%. The majority of the spores remained immobilized inside the fiber web; only 0.001 to 0.03% transferred to the foods. This amount is low compared with the process hygiene criteria and densities commonly found in food, and it does not endanger food safety. To measure this, we introduced BT-1 spores into the paper in densities of 100 to 1,000 times higher than the amounts of the B. cereus group bacteria found in commercial paper. Of BT-1 spores, 0.03 to 0.1% transferred from the paper to fresh agar surface within 5 min of contact, which is more than to food during 10 to 30 days of exposure. The findings indicate that transfer from paper to dry food is restricted to those microbes that are exposed on the paper surface and readily detectable with a contact agar method.
食品包装纸不是无菌的，因为其制造过程是开放的，且原材料中含有细菌。我们利用表达绿色荧光蛋白的苏云金芽孢杆菌 BT407Cry(-)[pHT315Omega(papha3-gfp)]构建体 BT-1 模拟了芽孢杆菌孢子从包装纸向食品转移的可能性。这种构建体被缩写为 BT-1。制造含有 BT-1 的纸张的设备允许纤维形成类似于全规模制造的纸张。在造纸过程中，BT-1 附着在纸浆上，并像真正的芽孢杆菌一样存活下来。将大米和巧克力暴露在含有 BT-1 的纸张中 10 或 30 天，温度分别为 40 或 20 摄氏度，相对空气湿度为 10 至 60%。大多数孢子仍然固定在纤维网内；只有 0.001 到 0.03%转移到食物中。与食品加工卫生标准和常见食品中发现的密度相比，这个数量很低，不会危及食品安全。为了测量这一点，我们将 BT-1 孢子以比商业纸张中发现的芽孢杆菌组细菌数量高 100 到 1000 倍的密度引入纸张中。在接触 5 分钟内，有 0.03 到 0.1%的 BT-1 孢子从纸张转移到新鲜琼脂表面，这比在暴露 10 到 30 天期间转移到食物中要多。这些发现表明，从纸张到干燥食品的转移仅限于暴露在纸张表面的微生物，并且可以通过接触琼脂法很容易地检测到。
