Carvacrol and thymol effect in vapor phase on Escherichia coli and Salmonella serovar Typhimurium growth inoculated in a fresh salad.

This study aimed to evaluate the antimicrobial effect of thymol and carvacrol in inhibiting Escherichia coli and Salmonella serovar Typhimurium inoculated on a fresh green salad through the vapor phase. A film-forming solution was prepared by dissolving starch, sorbitol, and variying concentrations of carvacrol, thymol, and a mixture of both. The film-forming solution containing the respective antimicrobial agent was then added lid, which was sealed rigidly and hermetically to achieve different concentrations (105 mg/L of air of carvacrol, 105 mg/L of air of thymol, and a mixture of 52 mg/L of air of carvacrol and 52 mg/L of air of thymol). Each active package contained fresh green salad inoculated with E. coli or Salmonella serovar Typhimurium. The active packages were then sealed and refrigerated at a temperature of 6 °C for 48 h. Growth/inhibition curves were modelled using the Weibull equation, and consumer acceptance was evaluated. Carvacrol can reduce up to 0.5 log-cycles, while thymol can reach almost 1 log cycle. Blending the components with half the concentration has a synergistic effect, inhibiting up to 2.5 log cycles. Consumer ratings revealed no significant differences between the packages. However, the average score was 5.4 on a 9-point hedonic scale, evaluators' comments did not indicate dislike or a strong taste characteristic of thymol and carvacrol.

Starch Edible Films/Coatings Added with Carvacrol and Thymol: In Vitro and In Vivo Evaluation against Colletotrichum gloeosporioides.

The aim of this work was to evaluate the in vitro and in vivo effectiveness of thymol and carvacrol added to edible starch films and coatings against Colletotrichum gloeosporioides. In vitro evaluation consisted of determining minimal inhibitory concentration (MIC) of carvacrol and thymol was determined at different pH values against Colletotrichum gloeosporioides. With MIC values, binary mixtures were developed. From these results, two coatings formulations were in vivo evaluated on mango and papaya. Physicochemical analysis, color change, fruit lesions and C. gloeosporioides growth were determined during storage. In vitro assay indicated that the MIC value of carvacrol and thymol against C. gloeosporioides was 1500 mg/L at pH 5. An additive effect was determined with 750/750 and 1125/375 mg/L mixtures of carvacrol and thymol, respectively. Coated fruits with selected mixtures of carvacrol and thymol presented a delay in firmness, maturity index and color change. Moreover, a fungistatic effect was observed due to a reduction of lesions in coated fruits. These results were corroborated by the increase in the lag phase value and the reduction of the growth rate. Carvacrol and thymol incorporated into edible films and coatings are able to reduce the incidence of anthracnose symptoms on mango and papaya.

A simple spectroscopic method to determine dimethoate in water samples by complex formation.

A simple and rapid method for the determination of dimethoate in water was developed based on the monitoring of the complex formation between bis 5-phenyldipyrrinate of nickel (II) and the herbicide dimethoate. The method showed a short response time (10 s), high selectivity (very low interference from other sulfate and salts), high sensitivity (limit of detection (LOD) 0.45 µM, limit of quantitation (LOQ) of 1.39 µM), and a Kd of 2.4 µM. Stoichiometry experiments showed that complex formation occurred with a 1:1 relation. The method was applied to different environmental water samples such as lagoon, stream, urban, and groundwater samples. The results indicated that independently from the water source, the method exhibited high precision (0.25-2.47% variation coefficient) and accuracy (84.42-115.68% recovery). In addition, the method was also tested using an effluent from a wastewater treatment plant from Mexico; however, the results indicated that the presence of organic matter had a pronounced effect on the detection.

Structural, Physical, and Antifungal Characterization of Starch Edible Films Added with Nanocomposites and Mexican Oregano (Lippia berlandieri Schauer) Essential Oil.

The aim of this study was to evaluate the structural, physical, and antifungal characteristics of starch edible films added with nanocomposites and Mexican oregano (Lippia berlandieri Schauer) essential oil (EO). Starch edible films were formulated with Mexican oregano EO (0%, 1%, or 2% v/v) and bentonite or halloysite (2%). Physical properties such as L* (luminosity), hue, film thickness, and O2 and CO2 permeability were determined. Structural analysis was carried out via atomic force microscopy (AFM). Antifungal activity against Aspergillus niger, Fusarium spp., and Rhizopus spp. was evaluated. The addition of EO and nanocomposites reduced luminosity, providing color to the edible films. Film thickness increased through the addition of EO concentration. O2 and CO2 permeability was increased by bentonite/EO films, and for halloysite films, CO2 permeability decreased as EO concentration increased. The addition of EO with both nanocomposites shows an evident morphological change in film structure, decreasing pore density and increasing pore size. In general, Mexican oregano EO added to edible starch films has an adequate fungicidal effect. The most sensitive microorganism tested was A. niger. Edible films added with Mexican oregano EO and nanocomposites show better physical and antifungal properties due to an adequate structural change in the biopolymer matrix.