Robertson W R, Muriana P M
Department of Animal Science and The Food and Agricultural Products Research and Technology Center, Oklahoma State University, Stillwater, Oklahoma 74078, USA.
J Food Prot. 2004 Jun;67(6):1177-83. doi: 10.4315/0362-028x-67.6.1177.
The effect of pH, processing temperatures, and preheating steps in two commercial egg white pasteurization procedures (Armour and Standard Brands methods) were evaluated using a five-strain cocktail of Salmonella. We devised a benchtop pasteurization system that would more closely resemble the two commercial processes than could the traditional capillary tube method. The pasteurization methods both require hydrogen peroxide to be metered into the egg white stream between a required initial preheat step and the main heating regimen. Both processes were evaluated at three pH levels (pH 8.2, 8.6, 9.0), at four temperatures (51.7 degrees C/125 degrees F, 53.1 degrees C/127.5 degrees F, 54.4 degrees C/130 degrees F, 55.8 degrees C/132.5 degrees F), and over four residence times to allow calculation of D-values at each temperature. When compared at the minimum allowable time and temperatures for each process, our results showed at least a 1-log greater log reduction (P < 0.05) for the Standard Brands method than the Armour method in 10 of 12 of the pH and temperature combinations tested. Almost all runs at any given temperature showed more reduction at pH 9.0 than at pH 8.2 except for the Standard Brands method at 54.4 degrees C and 55.8 degrees C, which showed the most consistent reduction across all three pH levels tested. Analysis of the preheat portion of the two methods showed that there was no contribution (P > 0.05) toward Salmonella reduction when compared with the identical process without the preheating step. We generally observed a greater reduction of Salmonella with egg white at pH 9.0 that is typical of older, off-line processing than with low pH egg white (i.e., 8.2) that is typical of modern in-line processing facilities. This difference was as much as 3.5 log cycles depending on the processing conditions. The data has been used to make recommendations for minimum processing conditions for hydrogen peroxide-based egg white pasteurization.
使用五种沙门氏菌菌株的混合菌液，评估了pH值、加工温度以及两种商业蛋清巴氏杀菌程序（阿穆尔法和标准品牌法）中的预热步骤的影响。我们设计了一种台式巴氏杀菌系统，该系统比传统的毛细管法更接近这两种商业流程。这两种巴氏杀菌方法都要求在所需的初始预热步骤和主要加热方案之间，将过氧化氢计量加入蛋清流中。在三个pH水平（pH 8.2、8.6、9.0）、四个温度（51.7℃/125℉、53.1℃/127.5℉、54.4℃/130℉、55.8℃/132.5℉）以及四个停留时间下对这两种工艺进行了评估，以便计算每个温度下的D值。当在每种工艺的最小允许时间和温度下进行比较时，我们的结果表明，在测试的12种pH和温度组合中的10种情况下，标准品牌法的对数减少量至少比阿穆尔法高1个对数级（P<0.05）。在任何给定温度下，几乎所有运行在pH 9.0时的减少量都比pH 8.2时更多，但标准品牌法在54.4℃和55.8℃时除外，该方法在测试的所有三个pH水平下显示出最一致的减少量。对这两种方法的预热部分进行分析表明，与没有预热步骤的相同工艺相比，预热对沙门氏菌减少没有贡献（P>0.05）。我们通常观察到，与现代在线加工设施典型的低pH蛋清（即pH 8.2）相比，pH 9.0的蛋清（这是较陈旧的离线加工的典型情况）对沙门氏菌的减少作用更大。根据加工条件，这种差异高达3.5个对数周期。这些数据已用于对基于过氧化氢的蛋清巴氏杀菌的最低加工条件提出建议。
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