Coriander, either fresh or inoculated with three strains of Escherichia coli O157:H7, Salmonella or Listeria monocytogenes, was treated with supercritical CO₂ (scCO₂, with and without drying) or freeze-dried. After drying in scCO₂ for 150 min at 80 bar and 35 °C, the aerobic plate count, yeasts and molds, and the Enterobacteriaceae were reduced by 2.80, 5.03, and 4.61 log CFU/g, respectively. The total count of mesophilic aerobic spores was not significantly reduced by the treatment. Freeze-drying induced lower reductions with 1.23, 0.87, and 0.97 log CFU/g, respectively. After treatment at 100 bar and 40 °C without drying, inoculated strains of E. coli O157:H7, Salmonella, and L. monocytogenes were inactivated by >7.37, >4.73 and 4.99 log CFU/g, respectively. After drying in scCO₂ for 150 min at 80 bar and 35 °C, the strains were reduced by >5.18 log CFU/g. Freeze-drying resulted in lower reduction with maximum 1.53, 2.03, and 0.71 log CFU/g, respectively. This study indicated that scCO₂ can be used for drying while offering a good inactivation of E. coli O157:H7, Salmonella, and L. monocytogenes as well as most of the bacteria in the vegetative form naturally occurring on coriander.

Industrial relevance

Although dried foods are considered microbiological stable foods and show adverse conditions to microbial growth, they may still host pathogenic microorganisms, which may proliferate upon sufficient rehydration. Highly contaminated commodities such as herbs and spices can pose a threat to consumer health if not processed carefully. There is therefore a need to develop or improve drying techniques which can provide dried foods while reducing the initial contamination to acceptable levels in a single process. CO₂ is a cheap, accessible solvent, with a low critical point (31 °C, 73.8 bar). Moreover, in the supercritical region, CO₂ exhibits potent microbicidal properties. Therefore, supercritical CO₂ drying could be a valuable alternative non-thermal technique for conventional drying methods, such as air-drying or freeze-drying, when medium to high value-added food products with high initial contamination are involved.

中文翻译：

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冷冻干燥和超临界CO ₂干燥灭活接种于香菜中的沙门氏菌，单核细胞增生性李斯特菌和大肠杆菌O157：H7

将新鲜或用三株大肠杆菌O157：H7，沙门氏菌或单核细胞增生李斯特菌接种的香菜用超临界CO ₂（scCO ₂，有和没有干燥）处理或冷冻干燥。在80 bar和35°C的scCO _2中干燥150分钟后，好氧板数，酵母菌和霉菌以及肠杆菌科的菌落分别降低了2.80、5.03和4.61 log CFU / g。通过处理，嗜温性好氧孢子的总数没有显着减少。冻干导致较低的减少，分别为1.23、0.87和0.97 log CFU / g。在100 bar和40°C下不干燥处理后，接种E菌株。大肠杆菌O157：H7，沙门氏菌，和大号。单核细胞增生因子分别被> 7.37，> 4.73和4.99 log CFU / g灭活。在scCO ₂中在80 bar和35°C下干燥150分钟后，菌株降低了> 5.18 log CFU / g。冷冻干燥导致较低的降低，分别为最大1.53、2.03和0.71 log CFU / g。该研究表明，scCO ₂可用于干燥，同时提供良好的E灭活性。大肠杆菌O157：H7，沙门氏菌，和大号。天然存在于香菜上的单核细胞增生因子以及营养形式的大多数细菌。

行业相关性

尽管干食品被认为是微生物稳定的食品，并且显示出不利于微生物生长的条件，但它们仍可能携带病原微生物，这些病原微生物在充分补液后可能会繁殖。如果不仔细加工，诸如药草和香料等高度污染的商品可能对消费者健康构成威胁。因此，需要开发或改进干燥技术，该技术可以提供干燥的食物，同时在单个过程中将初始污染降低到可接受的水平。CO ₂是一种廉价且易于获得的溶剂，其临界点较低（31°C，73.8 bar）。此外，在超临界区域，CO ₂表现出有效的杀微生物特性。因此，超临界CO ₂ 当涉及中度到高附加值，初始污染较高的食品时，干燥对于常规干燥方法（例如风干或冷冻干燥）可能是有价值的替代非热技术。