Rachon Grzegorz, Peñaloza Walter, Gibbs Paul A
Leatherhead Food Research, Randalls Road, Leatherhead, Surrey KT22 7RY, United Kingdom.
Nestlé Research Center, Lausanne, Vers-Chez-Les-Blanc, 1000 Lausanne 26, Switzerland.
Int J Food Microbiol. 2016 Aug 16;231:16-25. doi: 10.1016/j.ijfoodmicro.2016.04.022. Epub 2016 Apr 22.
The aims of this study were to obtain data on survival and heat resistance of cocktails of Salmonella, Listeria monocytogenes and the surrogate Enterococcus faecium (NRRL B-2354) in four low moisture foods (confectionery formulation, chicken meat powder, pet food and savoury seasoning) during storage before processing. Inoculated samples were stored at 16°C and cell viability examined at day 0, 3, 7 and 21. At each time point, the heat resistance at 80°C was determined. The purpose was to determine a suitable storage time of inoculated foods that can be applied in heat resistance studies or process validations with similar cell viability and heat resistance characteristics. The main inactivation study was carried out within 7days after inoculation, the heat resistance of each bacterial cocktail was evaluated in each low moisture food heated in thermal cells exposed to temperatures between 70 and 140°C. The Weibull model and the first order kinetics (D-value) were used to express inactivation data and calculate the heating time to achieve 5 log reduction at each temperature. Results showed that the pathogens Salmonella and L. monocytogenes and the surrogate E. faecium NRRL B-2354, can survive well (maximum reduction <0.8 log) in low moisture foods maintained at 16°C, as simulation of warehouse raw material storage in winter and before processing. The D80 value of the pathogens and surrogate did not significantly change during the 21day storage (p>0.05). The inactivation kinetics of the pathogens and surrogate at temperatures between 70 and 140°C, were different between each organism and product. E. faecium NRRL B-2354 was a suitable Salmonella surrogate for three of the low moisture foods studied, but not for the sugar-containing confectionery formulation. Heating low moisture food in moisture-tight environments (thermal cells) to 111.2, 105.3 or 111.8°C can inactivate 5 log of Salmonella, L. monocytogenes or E. faecium NRRL B-2354 respectively.
本研究的目的是获取沙门氏菌、单核细胞增生李斯特菌和替代菌屎肠球菌（NRRL B - 2354）的混合菌液在四种低水分食品（糖果配方、鸡肉粉、宠物食品和咸味调味料）加工前储存期间的存活和耐热性数据。接种后的样品在16°C下储存，并在第0、3、7和21天检测细胞活力。在每个时间点，测定80°C时的耐热性。目的是确定接种食品的合适储存时间，以便应用于具有相似细胞活力和耐热性特征的耐热性研究或工艺验证。主要的灭活研究在接种后7天内进行，在暴露于70至140°C温度的热室中加热每种低水分食品，评估每种混合菌液的耐热性。使用威布尔模型和一级动力学（D值）来表示灭活数据，并计算在每个温度下实现5个对数减少所需的加热时间。结果表明，作为冬季和加工前仓库原料储存的模拟，沙门氏菌、单核细胞增生李斯特菌和替代菌屎肠球菌NRRL B - 2354在保持在16°C的低水分食品中能很好地存活（最大减少量<0.8个对数）。在21天的储存期间，病原体和替代菌的D80值没有显著变化（p>0.05）。在70至140°C温度下，每种微生物和产品之间病原体和替代菌的灭活动力学不同。屎肠球菌NRRL B - 2354是所研究的三种低水分食品中沙门氏菌的合适替代菌，但不适用于含糖的糖果配方。在密封环境（热室）中将低水分食品加热到111.2、105.3或111.8°C，可分别使5个对数的沙门氏菌、单核细胞增生李斯特菌或屎肠球菌NRRL B - 2354失活。
