Ciencia e Ingeniería en Alimentos y Biotecnología
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Item Uso de las propiedades antimicrobianas del quitosano contra patógenos alimentarios(Universidad Técnica de Ambato. Facultad de Ciencia e Ingeniería en Alimentos y Biotecnología. Carrera de Alimentos, 2025-02) Flores Barona, Joselyne Anabell; Sánchez Garnica, Manoella AlejandraThis study focuses on the antimicrobial properties of chitosan to combat foodborne pathogens present in fresh cheeses, a significant public health problem due to foodborne illnesses. Pathogens such as Escherichia coli and Staphylococcus aureus are responsible for numerous foodborne infections, highlighting the need for effective alternatives to synthetic preservatives. The main objective of this study was to evaluate the efficacy of chitosan as an antimicrobial agent against these pathogens. The methodology included the determination of the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) by microdilution and disc diffusion techniques. Chitosan solutions were prepared, and their effects on E. coli and S. aureus strains isolated from fresh cheeses were evaluated. The results showed that chitosan had an MIC of 165 micrograms per millilitre for E. coli and 10 micrograms per millilitre for S. aureus, indicating an increased susceptibility of gram-positive bacteria. In addition, inhibition percentages of 62.5 percent for E. coli and 60 percent for S. aureus were observed. The most relevant findings suggest that chitosan is a promising natural preservative capable of inhibiting the growth of food pathogens, which could improve food safety and extend the shelf life of dairy products such as fresh cheeses without compromising their quality. Further studies are recommended to optimize its application in the food industry.Item Evaluación de la actividad antimicrobiana in vitro de aceites esenciales frente a microorganismos patógenos y del deterioro de alimento(Universidad Técnica de Ambato. Facultad de Ciencia e Ingeniería en Alimentos y Biotecnología. Carrera de Biotecnología, 2025-02) Chango Chimborazo, Yajaira Estefania; Arancibia Soria, Mirari YosuneEssential oils (EOs) are volatile compounds, rich in secondary metabolites such as monoterpenes and sesquiterpenes, noted for their antimicrobial activity, attributed to their hydrophobicity and high concentration of active phenols (thymol, carvacrol, and eugenol). These compounds alter the integrity of microbial membranes, increasing their permeability and generating oxidative stress. The agar diffusion method is used to categorize antimicrobial activity into four levels (+++; fully inhibited, ++; partially inhibited, +; slightly inhibited, and -; no inhibition). However, this method presented limitations due to the volatility and hydrophobicity of EOs, which affected their uniform diffusion. The in vitro evaluation of 50 EOs against 12 microorganisms revealed greater efficacy against Gram-positive bacteria due to their more permeable cell wall. Although Gram-negative bacteria are more resistant due to their complex outer membrane. EOs such as thyme and oregano were able to inhibit them thanks to their bioactive compounds. In contrast, anaerobic Clostridium perfringens showed complete resistance, likely due to their spore-forming capacity and the reduced production of reactive oxygen species (ROS) in the absence of oxygen, which limits the antimicrobial action of EOs. In fungi, thyme and cinnamon showed significant activity, while against beneficial bacteria the action was minimal. Their efficacy depends on the active compounds, oil volatility, and experimental conditions. Finally, EOs represent a sustainable and natural alternative as antimicrobial agents, aligning with the Sustainable Development Goals (SDGs). Their application in the food and pharmaceutical industries can improve food safety and meet the demand for natural preservatives in consumer products.Item Evaluación de las propiedades antimicrobianas del hongo cola de pavo (Trametes versicolor (L.) Lloyd) y su aplicación como conservante en queso fresco(Universidad Técnica de Ambato. Facultad de Ciencia e Ingeniería en Alimentos y Biotecnología. Carrera de Alimentos, 2025-02) Arteaga Teneda, Andrés Leonardo; Sánchez Garnica, Manoella AlejandraThe excessive consumption of processed foods with high levels of chemical additives has generated concern owing to the potential adverse effects on human health in both the short and long term. In this context, fungi have been proposed as promising alternatives for the production of natural food additives because of their functional and beneficial properties, as well as their ability to replace synthetic additives. For this purpose, a methanolic extract of the turkey tail fungus (Trametes versicolor (L.) Lloyd) was developed using the maceration method, which achieved the extraction of secondary metabolites together with the solvent methanol. The antimicrobial properties of the extract were evaluated using the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) against Escherichia coli ATCC 11775 and Staphylococcus aureus ATCC 25923, using resazurin as an indicator, which allowed the observation of coloration changes. For food application, a fresh cheese was developed incorporating the fungus extract, and its shelf life was determined by counting colony forming units (CFU) per gram of Enterobacteriaceae for 5 days. In addition, the Arrhenius equation was used to predict its stability by comparing it with a traditional preservation method such as brine. The T. versicolor extract exhibited antimicrobial properties, as evidenced by the inhibition of the growth of the studied strains of E. coli and S. aureus, as confirmed by MIC and BMC assays. Likewise, the extract showed preservative effects in fresh cheese that were comparable to those obtained with brine, according to the results obtained through the prediction of shelf life based on the Arrhenius equation.