Karolenko Caitlin E, Wilkinson Jade, Muriana Peter M
Robert M. Kerr Food and Agricultural Product Center, Oklahoma State University, Stillwater, OK 74078, USA.
Department of Animal and Food Sciences, Oklahoma State University, Stillwater, OK 74078, USA.
Microorganisms. 2022 Aug 15;10(8):1648. doi: 10.3390/microorganisms10081648.
Validation studies conducted within a food processing facility using surrogate organisms could better represent the manufacturing process than controlled laboratory studies with pathogenic bacteria on precision equipment in a BSL-2 lab. The objectives of this project were to examine potential surrogate bacteria during biltong processing, conduct biltong surrogate validation lethality studies, and measure critical factors and intrinsic parameters during processing. Beef pieces (1.9 cm × 5.1 cm × 7.6 cm) were inoculated with four-strain mixtures of Carnobacterium divergens/C. gallinarum, Pediococcus acidilactici/P. pentosaceous, and Biotype 1 E. coli ATCC BAA (-1427, -1428, -1429, and -1430), as well as a two-strain mixture of Latilactobacillus sakei and other commercially available individual bacterial cultures (P. acidilactici Saga200/Kerry Foods; Enterococcus faecium 201224-016/Vivolac Cultures). Inoculated beef was vacuum-tumbled in marinade and dried in a humidity-controlled oven for 8−10 days (24.9 °C; 55% relative humidity). Microbial enumeration of surviving surrogate bacteria and evaluation of intrinsic factors (water activity, pH, and salt concentration) were performed post inoculation, post marination, and after 2, 4, 6, 8, and 10 days of drying. Trials were performed in duplicate replication with triplicate samples per sampling time and analyzed by one-way RM-ANOVA. Trials conducted with E. faecium, Pediococcus spp., and L. sakei never demonstrated more than 2 log reduction during the biltong process. However, Carnobacterium achieved a >5 log (5.85 log) reduction over a drying period of 8 days and aligned with the reductions observed in previous trials with pathogenic bacteria (Salmonella, E. coli O157:H7, L. monocytogenes, and S. aureus) in biltong validation studies. Studies comparing resuspended freeze-dried or frozen cells vs. freshly grown cells for beef inoculation showed no significant differences during biltong processing. Carnobacterium spp. would be an effective nonpathogenic in-plant surrogate to monitor microbial safety that mimics the response of pathogenic bacteria to validate biltong processing within a manufacturer’s own facility.
在食品加工设施中使用替代微生物进行的验证研究，相较于在生物安全二级实验室的精密设备上对病原菌进行的对照实验室研究，能更好地反映制造过程。本项目的目标是检测干腌牛肉加工过程中的潜在替代细菌，进行干腌牛肉替代验证致死率研究，并测量加工过程中的关键因素和内在参数。将牛肉块（1.9厘米×5.1厘米×7.6厘米）接种上分歧肉杆菌/鸡源肉杆菌、嗜酸乳杆菌/戊糖片球菌的四菌株混合物，以及1型大肠杆菌ATCC BAA（-1427、-1428、-1429和-1430），还有清酒乳杆菌的双菌株混合物和其他市售单一细菌培养物（嗜酸乳杆菌Saga200/克里食品公司；粪肠球菌201224-016/维沃拉克培养物）。接种后的牛肉在腌料中进行真空翻滚处理，然后在湿度控制的烤箱中干燥8至10天（24.9℃；相对湿度55%）。在接种后、腌制后以及干燥2、4、6、8和10天后，对接种后存活的替代细菌进行微生物计数，并评估内在因素（水分活度、pH值和盐浓度）。试验进行了重复，每个采样时间有三个重复样本，并通过单向重复测量方差分析进行分析。在干腌牛肉加工过程中，用粪肠球菌、片球菌属和清酒乳杆菌进行的试验，其菌数减少从未超过2个对数。然而，在8天的干燥期内，肉杆菌属的菌数减少超过了5个对数（5.85个对数），这与之前干腌牛肉验证研究中对病原菌（沙门氏菌、大肠杆菌O157:H7、单核细胞增生李斯特菌和金黄色葡萄球菌）观察到的菌数减少情况一致。比较用于牛肉接种的冻干或冷冻重悬细胞与新鲜培养细胞的研究表明，在干腌牛肉加工过程中没有显著差异。肉杆菌属将是一种有效的非致病性厂内替代物，用于监测微生物安全性，它能模拟病原菌的反应，以验证制造商自身设施内的干腌牛肉加工过程。
