The effect of oregano (Origanum vulgare) essential oil on four Salmonella serovars and shelf life of refrigerated pork meat packaged under vacuum and modified atmosphere

The survival of Salmonella Enteritidis, S. Typhimurium, S. Infantis, and S. Montevideo in experimentally inoculated (10(6) CFU/g) minced pork meat containing different concentrations (0%, 0.3%, 0.6%, or 0.9%) of oregano (Origanum vulgare) essential oil (OEO) packaged under vacuum or MAP (30%O-2/50%CO2/20%N-2) were evaluated within 15 days of refrigeration (3 +/- 1 degrees C) storage. Carvacrol was the predominant constituent in OEO (77.16%). The minimum inhibitory concentration of OEO was similar for all Salmonella serovars (160-320 mu g/ml). Salmonella counts in minced pork were reduced by 2.09 and 3.08 log CFU/g in the samples treated with 0.3% and 0.6% OEO, respectively. Addition of 0.9% OEO reduced the Salmonella count to below the limit of detection. Experiments also included investigation of OEO effect on Enterobacteriaceae, LAB and TVC. For both packaging methods the use of OEO increased the microbial shelf life of pork. Sensory analyses showed that the samples with 0.3% OEO added were the most acceptable. Practical applications Due to its nutritional characteristics, minced meat is suitable for the growth of most microorganisms including spoilage bacteria and foodborne pathogens such as Salmonella spp. The microbial safety of minced meat is very important. Taking into account that these bacteria are one of the most important from the aspect of meat safety, their control, especially in minimally processed meat products, is crucial. OEO not only exhibited strong anti-Salmonella effects, but, in contrast to some other essential oils, is categorized as "GRAS" (generally recognized as safe) and can be considered as a natural preservative used in organic production as an alternative to synthetic additives. Our findings could also guide the selection of an effective concentration of OEO that is organoleptically acceptable.