Abstract
The aim of this study was to investigate the combined effect of carvacrol, thymol and nisin against Staphylococcus aureus and the combined effect of carvacrol and thymol against Salmonella Enteritidis. Minimum inhibitory concentrations (MIC) of carvacrol, thymol, and nisin for S. aureus were 200, 150 and 30 µg/mL, respectively. MIC of carvacrol and thymol for Salmonella Enteritidis was 200 µg/mL. A factorial method of independent variables was then used to study the combined effect of antimicrobials. Results showed that combinations of carvacrol-thymol-nisin (reduction of 1.2 log CFU/mL for MIC and 4.98 log CFU/mL for 2MIC), carvacrol-thymol (reduction of 1.33 log CFU/mL for 2MIC), nisin-thymol (reduction of 3.52 log CFU/mL for 2MIC) and nisin-carvacrol (reduction of 3.41 log CFU/mL for 2MIC) attained a significant inhibition of S. aureus. Similarly, there was significant reduction of Salmonella Enteritidis due to combined effect of thymol-carvacrol (reduction of 4.5 log CFU/mL for MIC and inhibition below detection limit for 2MIC). Therefore, the combinations of natural antimicrobials described in this work showed potential to be used as an additional barrier for food safety.
Key words
antimicrobial; factorial design; pathogens; response surface analysis
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