Cargill Food Safety Research and Scientific Services, 300 West 1st Street North, Wichita, Kansas 67202.
Silliker Food Science Center, 3600 Eagle Nest Drive, Crete, Illinois 60417, USA.
J Food Prot. 2022 Apr 1;85(4):647-652. doi: 10.4315/JFP-21-316.
Bacillus weihenstephanensis can grow at refrigeration temperature and cause food poisoning. It has been isolated from liquid whole egg products. The moderate heat used for pasteurization of liquid egg products is ineffective for killing spore-forming bacteria, including Bacillus. Available predictive models and a pretrial study in broth suggested the potential for growth of Bacillus spp. under the tested conditions. Hence, hurdles such as storage of product below 4°C or use of preservatives would be needed to ensure the food safety of pasteurized egg products. This study evaluated the growth inhibition of B. weihenstephanensis in pasteurized liquid whole egg product formulated with 6.25 ppm of nisin during storage at refrigerated and refrigerated temperatures at abuse levels for a total 13 weeks in three replicate trials. At day 0, the product had a pH of 7.52 ± 0.29, while background microflora, such as aerobic plate counts (APC), presumptive Bacillus cereus and yeast and molds were <10 CFU/g. Product inoculated with target 2.5 log CFU/g of B. weihenstephanensis, stored at 4°C for 4 weeks and subsequently at 7 or 10°C for 9 weeks, exhibited no growth in all three replicate trials. Average counts reduced (P < 0.05) by at least 1 log in 6 weeks in all samples stored at either 7 or 10°C. Similarly, growth of total plate counts, presumptive Bacillus spp., and yeast and mold counts was not observed in uninoculated controls stored at 4°C for 4 weeks and subsequently at 7 or 10°C for 9 weeks. Visual and odor evaluation performed at each sampling time point showed no abnormalities. This study assessed the efficacy of the maximum level of nisin allowed for use in pasteurized liquid whole eggs and validated the inhibition of B. weihenstephanensis in the product for an extended shelf life of up to 13 weeks.
凝结芽孢杆菌可以在冷藏温度下生长并导致食物中毒。它已从液态全蛋液产品中分离出来。巴氏杀菌液态蛋制品所用的中等热量对孢子形成细菌（包括芽孢杆菌）无效。现有的预测模型和肉汤预试验研究表明，在测试条件下芽孢杆菌属可能会生长。因此，需要采取措施确保巴氏杀菌蛋制品的安全，例如将产品储存在 4°C 以下或使用防腐剂。本研究评估了在 3 次重复试验中，在冷藏和冷藏温度下滥用条件下，在巴氏杀菌液态全蛋液产品中添加 6.25ppm 乳链菌肽的情况下，凝结芽孢杆菌的生长抑制情况。在 0 天，产品的 pH 值为 7.52±0.29，而背景微生物，如需氧平板计数（APC）、推定的蜡样芽孢杆菌和酵母和霉菌，<10 CFU/g。产品接种目标 2.5 log CFU/g 的凝结芽孢杆菌，在 4°C 下储存 4 周，然后在 7 或 10°C 下储存 9 周，在所有 3 次重复试验中均未观察到生长。在所有在 7 或 10°C 下储存的样品中，6 周内平均计数减少（P<0.05）至少 1 个对数级。同样，在 4°C 下储存 4 周，然后在 7 或 10°C 下储存 9 周的未接种对照中，也未观察到总平板计数、推定的芽孢杆菌属和酵母和霉菌计数的增长。在每个采样时间点进行的视觉和气味评估均未显示异常。本研究评估了巴氏杀菌液态全蛋液中允许使用的最大乳链菌肽水平的效果，并验证了该产品中凝结芽孢杆菌的抑制作用，可将保质期延长至 13 周。
