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The importance of the diterpenic and rosmarinic acid content in the biological activities of rosemary extracts has been studied previously, but how the relationship between the concentration of these components affects their antioxidant and antibacterial activities has received little attention. Accordingly, from a total of 150 plants, 27 methanolic extracts were selected, for their similar diterpene contents but different ratios between carnosic acid and carnosol concentrations. In extracts with similar rosmarinic acid contents but differing proportions between carnosic acid and carnosol, the two diterpenes were seen to equally affect the in vitro antioxidant activity; however, and related with the antibacterial efficiency, this biological activity improved when carnosol was the major diterpene component.

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The effect of the ecological traits of the different bioclimatic areas of the province of Murcia on the chemical variability and antioxidant and bacteriostatic activities of individual rosemary extracts was studied. The main findings confirmed that a high thermicity index, favors both the methanolic extracts yielded by these shrubs and their biological activities. However, differences in their polyphenolic composition should be attributed to the genetic heritage of these plants rather than to the bioclimatic conditions in which they grow. As regards the relationship between the chemical composition of these extracts and their biological activities, it was noted that a high phenolic acid content, especially of rosmarinic acid, may increase the antioxidant activity exhibited by extracts containing high levels of carnosic acid. The bacteriostatic activity was higher (p< 0.05) in those extracts in which carnosic acid was the major component quantified.

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The food industry is in need of rapid, reliable methodologies for the detection of Listeria monocytogenes in ready-to-eat products, as an alternative to the International Organization of Standardization (ISO) 11290-1 reference method. The aim of this study was to evaluate impedanciometry combined with chromogenic agar culture for the detection of L. monocytogenes in dry-cured ham. The experimental setup consisted in assaying four strains of L. monocytogenes and two strains of Listeria innocua in pure culture. The method was evaluated according to the ISO 16140:2003 standard through a comparative study with the ISO reference method with 119 samples of dry-cured ham. Significant determination coefficients ( R of up to 0.99) for all strains assayed in pure culture were obtained. The comparative study results had 100% accuracy, 100% specificity, and 100% sensitivity. Impedanciometry followed by chromogenic agar culture was capable of detecting 1 CFU/25 g of food. L. monocytogenes was not detected in the 65 commercial samples tested. The method evaluated herein represents a promising alternative for the food industry in its efforts to control L. monocytogenes. Overall analysis time is shorter and the method permits a straightforward analysis of a large number of samples with reliable results.

Comparative evaluation of impedanciometry combined with chromogenic agars or RNA hybridization and real-time PCR methods for the detection of L. monocytogenes in dry-cured ham, Food Control (2018),