No abstract

No abstract

The aims of this work were to study the antimicrobial activity of nine monoterpenes and the synergistic or antagonistic associations between them, and to relate water solubility, H-bonding and pKa values with antimicrobial activity. The minimum inhibitory concentrations (MICs) and minimum bactericidal concentration (MBCs) were determined. The MIC of carvacrol against S. aureus was 3.2 g/l and of thymol was 7.5 g/l. E. coli was resistant. Carvacrol and thymol were bactericidal. The associations geraniol/menthol against S. aureus and B. cereus and thymol/menthol against B. cereus were totally synergistic. Eugenol/geraniol displayed partial synergism against B. cereus. The other groups did not show any synergistic eff ect. Eugenol had the lowest pKa, followed by thymol and carvacrol. Eugenol had the highest total area and polar area and intermolecular and intramolecular hydrogen-bonding capacity, while carvacrol and thymol only had intermolecular hydrogenbonding capacity. The terpenes alone and in combination were eff ective against microorganisms. Phenolic compounds were the most active terpenes. Associations between terpenes were related to the chemical structure. Studies on the antimicrobial activity of associations of terpenes will advance the search for new alternatives for food preservation.

Poultry meat is particularly prone to oxidative deterioration due to its high concentration of polyunsaturated fatty acids. The present study evaluates the effects of thymol and its isomer carvacrol on lipid oxidation when supplemented to the feed. Supplementation with the antioxidant butylated hydroxytoluene was used as a positive control. Thus, broiler chickens were assigned to 1 of 4 treatments: vehicle (control), 150 mg/kg of butylated hydroxytoluene (positive control), 150 mg/kg of thymol, or 150 mg/kg of carvacrol. Breast and thigh samples were taken at 0, 5, and 10 d of 4 degrees C storage. Lipid oxidation was determined by the analysis of 2-TBA reactive substances (TBARS). Sample storage for 5 to 10 d significantly increased the levels of TBARS. Feed supplementation did not significantly affect breast sample oxidation. However, after 5 and 10 d of storage, increasingly higher values of TBARS were detected in thigh samples of the control group in comparison to the 3 supplemented groups. Interestingly, the same lower values of TBARS were detected between those feed-supplemented groups. Therefore, the application of the natural antioxidants thymol or carvacrol could be useful to improve poultry meat quality.

No abstract

No abstract

No abstract

The aim of this work was to compare the antiradical activity, total phenol content (TPC), and essential oil composition of Origanum vulgare spp. virens, Origanum x applii, Origanum x majoricum, and O. vulgare spp. vulgare cultivated in Argentina in different localities. The experiment was conducted in the research station of La Consulta (INTA-Mendoza), the research station of Santa Lucia (INTA-San Juan), and Agronomy Faculty of National University of La Pampa, from 2007 to 2008. The composition of the essential oils of oregano populations was independent of cultivation conditions. In total, 39 compounds were identified in essential oils of oregano from Argentina by means of GC-MS. Thymol and trans-sabinene hydrate were the most prominent compounds, followed by gamma-terpinene, terpinen-4-ol, and alpha-terpinene. O. vulgare vulgare is the only Origanum studied which is rich in gamma-terpinene. Among tested oregano, O. x majoricum showed the highest essential oil content, 3.9 mg g(-1) dry matter. The plant extract of O. x majoricum had greater total phenol content values, 19.36 mg/g dry weight, than the rest of oregano studied. To find relationships among TPC, free radical scavenging activity (FRSA), and climate variables, canonical correlations were calculated. The results obtained allow us to conclude that 70% of the TPC and FRSA variability can be explained by the climate variables (R(2) = 0.70; p = 8.3 x 10(-6)), the temperature being the most important climatic variable.