Abstract:

Coalho cheese is a semi-hard cheese with medium to high moisture that is obtained by a simple manufacture process usually using commercial coagulating agent and starter of the mesophilic lactic cultures Lactococcus lactis subsp. cremoris and L. lactis subsp. lactis. However, the physicochemical characteristics of this dairy product may favor the survival and growth of the pathogenic bacteria frequently associated to foodborne diseases. The current trend of a negative consumer perception of chemical preservatives increases the interest in use of essential oils, particularly which obtained from Origanum vulgare L. (OVEO), as antimicrobial compounds for food preservation. However there is a lack of information regarding the effects of this oil against starter cultures. This study assessed the activity of OVEO against the mesophilic lactic cultures (L. lactis subsp. cremoris and L. lactis subsp. lactis - Chr. Hansen Brazil®) used as starter in manufacture of coalho cheese and against Staphylococcus aureus ATCC 6538 and Listeria monocytogenes ATCC 7644 strains. The minimum inhibitory concentration (MIC) was performed by microdilution in broth assays using OVEO (Ferquima® Ltda) concentrations from 0.3 to 40 Andamp;#956;L/mL, according procedures preconized by Clinical and Laboratory Standards Institute. All bacterial suspensions were standardized (10Andlt;supAndgt;8Andlt;/supAndgt;) and tested in single and mixed cultures (1:1) for S. aureus or L. monocytogenes and in a mixed culture (1:1) for lactic starter strains. MIC values of OVEO for S. aureus and L. monocytogenes were 2.5 Andamp;#956;L/mL in single culture, while for mixed culture lower MIC value was observed (1.25 Andamp;#956;L/mL). In assays with the mixed culture of L. lactis subsp. cremoris and L. lactis subsp. lactis. OVEO showed MIC value of 0.60 Andamp;#956;L/mL. The results suggest the OVEO as an interesting approach to inhibit pathogens frequently associated to coalho cheese, however the inhibitory effects against starter lactic culture need be considered for the application of OVEO in this product.