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P3-89 Antimicrobial Activity of Thymus vulgaris L. and Origanum vulgare L. Essential Oils against Pathogenic and Starter Bacteria in Brazilian Semi-Hard Cheese Model

Tuesday, July 28, 2015
Hall B (Oregon Convention Center)
Marciane Magnani , Department of Food Engineering, Center of Technology, Federal University of Paraíba , João Pessoa , Brazil
Donald W. Schaffner , Rutgers University , New Brunswick , NJ
Rayssa J Carvalho , Department of Food Engineering, Center of Technology, Federal University of Paraiba , João Pessoa , Brazil
Geany T Souza , Department of Food Engineering, Center of Technology, Federal University of Paraiba , João Pessoa , Brazil
Evandro L Souza , Department of Nutrition, Center of Health Sciences, Federal University of Paraíba , João Pessoa , Brazil
Introduction: Coalho cheese is a semi-hard Brazilian cheese with medium to high moisture obtained by a simple manufacturing process usually using mesophilic lactic starter cultures. Essential oils from Origanun vulgare L. (OVEO) and Thymus vulgaris L. (TVEO) are recognized as safe antimicrobial compounds, however there is a lack of information regarding the effects of these oils against starter and pathogenic bacteria in cheese. 

Purpose: The aim of this study was to evaluate the activity of OVEO and TVEO against starter mesophilic cultures L. lactis subsp. cremoris and L. lactis subsp. lactis, and strains of pathogens S. aureus and L. monocytogenes in a coalho cheese-based model system.  

Methods: Samples of coalho cheese (10 g) containing OVEO or TVEO at Minimal Inhibitory Concentration were inoculated with 1 ml of bacterial suspension (107 CFU/ml), blended for 5 min and incubated at 8 - 10°C. Systems without oils were assayed similarly. The number of viable cells in the systems was counted at various time points (0, 24, 48 and 72 h) by serial dilution and plating on M17 Agar, Brain Heart Agar added of sodium chloride 8.5%, or Listeria Agar for starter cultures, S. aureus and L. monocytogenes, respectively 

Results: Starter and pathogenic bacteria in systems containing essential oils always exhibited lower viable cells counts (P ≤ 0.05) compared to control systems. After 72 h, reduction of 2.85 log CFU/g, 1.85 log CFU/g and 0.53 log CFU/g was observed for L. monocytogenes, S. aureus and starter bacteria in cheese containing OEOV, respectively. In systems with added TVEO, a reduction of 2.15 CFU/g, 1.22 CFU/g and 0.64 CFU/g LAB was observed for L. monocytogenes, S. aureus and starter, respectively. 

Significance: The results suggest OVEO or TVEO may inhibit pathogens frequently associated to coalho cheese. Both compounds have some inhibitory effects against starter lactic culture needed to produce this product.

Back to: Poster Session 3 – Laboratory and Detection Methods, Sanitation; Antimicrobials; Produce; Epidemiology
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