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.

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.

Biofilms are difficult to eliminate with standard antimicrobial treatments due to their high antibiotic resistance. Therefore, some plants contain natural compounds with antimicrobial activity that can control biofilm formation. The aim of this work was to evaluate the effect of Mexican oregano (Lippia berlandieri Schauer) essential oil (EO) on Pseudomonas aeruginosa and Salmonella Thyphimurium biofilm formation on stainless steel surfaces. EO was added to achieve final concentrations of 0, 200, 250, 300, 400, 600, 800, and 1,600 mg/L. Growth data were modeled using the modified Gompertz model. EO antimicrobial activity against biofilm can be observed for both microorganisms. Moreover, at an EO concentration below inhibition, there is a delay in biofilm formation, thus decreasing the number of microorganisms that are part of the biofilm. The maximum growth rate in biofilm formation showed an inversely proportional behavior in relation to EO concentration. P. aeruginosa requires nearly 1 h to start forming biofilms. There is a delay in biofilm formation, thus decreasing the number of microorganisms that are part of the biofilm (24 h for 400 mg/L and 18 h for 600 mg/L). Salmonella Thyphimurium biofilm formation is affected at 200 mg/L of Mexican oregano EO, causing film detachment from the stainless steel surface after 18 h, while at 250 mg/L biofilm formation was inhibited. Mexican oregano EO could inhibit the development of P. aeruginosa and Salmonella Thyphimurium biofilm formation on stainless steel surfaces. Salmonella was more susceptible than Pseudomonas to Mexican oregano EO according to the concentrations required to inhibit biofilm growth.

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This study was designed to identify the bacteria and yeasts from the milk samples of dairy cattle presenting with subclinical mastitis and evaluate their antimicrobial susceptibility. We collected a total of 52 milk samples from cows across three farms in San Salvador El Seco (Puebla, Mexico). Microbial isolation was performed using microbiological techniques followed by taxonomic identification of bacteria and yeasts. Antimicrobial susceptibility was evaluated using the guidelines provided by the Clinical Laboratory Standard Institute (CLSI). 1 We identified three genera and six species of yeasts including Candida glabrata, C. krusei, C. lipolytica, Cryptococcus laurentii, Rhodotorula rubra, and R. glutinis and five species of bacteria, including Staphylococcus saprophyticus, S. aureus, S. hominis, S. epidermidis, and Streptococcus disgalactiae. All of the yeast strains were sensitive to amphotericin B; 1/23 (4.3%) were resistant to ketoconazole and nystatin, 10/23 (43%) were resistant to fluconazole, and 13/23 (53%) were resistant to 5-fluorocytosine. The dominant genus isolated was Candida, with the most abundant groups being C glabrata and C. krusei. Resistance to 5-fluorocytosine was observed in all yeasts except C. lipolytica, while both S. aureus and S. epidermidis were resistant to oxacillin and dicloxacillin. S. hominis was resistant to gentamicin. These antimicrobials are still used in bovine therapy for mastitis, directly affecting healthy cattle and, therefore, raw milk.