A synergistic mixture of Origanum vulgare L. and Rosmarinus officinalis L. essential oils to preserve overall quality and control Escherichia coli O157:H7 in fresh cheese during storage

The effects of Origanum vulgare L. (OVEO) and Rosmarinus officinalis L. (ROEO) essential oils in combination on the counts of a mesophilic starter co-culture and Escherichia coli O157:H7 in cheese were determined during 21 days of refrigerated storage. Prevalent OVEO and ROEO terpenes, as well as the physicochemical and sensory aspects of cheese, were also determined. OVEO (0.03 mu L/g) and ROEO (1.32 mu L/g) did not decreased the counts of Lactococcus spp. while caused a decrease of approximately 3.0 log CFU/g in counts of E. coli O157:117 in the earlier 12 days of storage. Terpenes of OVEO and/or ROEO decreased during storage in cheese and showed a correlation with decreases in E. coli O157:H7 counts. Eucalyptol, camphor, a-pinene and camphene were detected until 18 days of storage, and only eucalyptol, camphor and a-pinene were detected until 21 days of storage. OVEO and ROEO did not affect the physicochemical parameters and characterized the cheese by the refreshing aroma, mint-like flavor and softness. These results show the prevalent terpenes of OVEO and ROEO in fresh cheese during refrigerated storage and suggest their incorporation during manufacture as a strategy to preserve this product, with particular effects on the survival of E. coil O157: H7.