Search

En el marco de la asignatura “Control Químico de la Calidad de los Alimentos”, una asignatura optativa del Grado de Nutrición Humana y Dietética se ha implantado una actividad de carácter práctico con el fin de seguir un modelo de docencia no solo enfocado a la transmisión de contenidos, sino centrado en la adquisición de competencias. Dada la formación recibida a lo largo del Grado se han detectado carencias en las competencias específicas de trabajo de laboratorio y gestión de trabajos de investigación en los estudiantes. Mediante la realización de un Trabajo de Iniciación a la Investigación, ya implementado en una asignatura del Grado de Química, se han desarrollado y mejorado estas competencias. Esta experiencia educativa fue evaluada por los estudiantes a través de la realización de una autoevaluación sobre el estado inicial de esas competencias, que se realizó al comienzo de la asignatura, y el grado de consecución y aplicación de las competencias desarrolladas, cuestionario realizado al finalizar la actividad. Del análisis de los datos recabados se desprende que el estudiante sí que observa una clara mejora en el desarrollo y su capacidad de aplicación de estas competencias.

En el seno de la asignatura Química de los Alimentos del cuarto curso del Grado en Química, los estudiantes realizan un trabajo de iniciación a la investigación (TII), donde llevan a cabo una búsqueda bibliográfica que precede a la realización de experimentos en el laboratorio y, finalmente, redactan un artículo científico que es defendido públicamente. De este modo, los estudiantes desarrollan diferentes competencias específicas y transversales y emprendedoras, no sólo con el campo de la investigación, sino relacionadas con el trabajo autónomo y toma de decisiones que son de gran importancia para la incorporación al mercado laboral. La experiencia acumulada desde el curso 2013/14 hace que nos encontremos en un momento propicio para evaluar el trabajo realizado hasta la fecha, en términos de mejora de la empleabilidad de nuestros egresados. El perfil profesional de los estudiantes en Química pretende cubrir las necesidades requeridas por empresas del sector industrial y de servicios donde lo/as egresado/as podrán desarrollar su carrera profesional. El TII planteado permite a los estudiantes mostrar de forma integrada los contenidos formativos recibidos y las competencias adquiridas asociadas al título de Grado, además permite que el alumno demuestre su capacitación como profesional.

In this work, different analytical techniques (thermal analysis, 13C cross-polarization magic angle spinning (CPMAS) NMR and Fourier transform infrared (FT-IR) spectroscopy) have been used to study the organic matter changes during the co-composting of pig slurry with cotton gin waste. To ensure the validity of the findings, the composting process was developed in different scenarios: under experimental pilot plant conditions, using the static pile system, and under real conditions on a pig farm, using the turning pile system. Also, the thermal stability index (R1) was determined before and after an extraction with water, to evaluate the effect of eliminating water-soluble inorganic salts on the thermal analysis. The results of the thermal methods showed the degradation of the most labile organic matter during composting; R1 increased during composting in all piles, without any influence of the presence of water-soluble inorganic ions in the sample. The NMR showed a decrease in the abundance of the carbohydrate molecules and an increase in the aliphatic materials during composting, due to a concentration effect. Also, FT-IR spectroscopy was a useful technique to study the trends of polysaccharides and nitrate, as indicators of organic matter transformations during composting.

The management of biodegradable wastes is increasing, including the use of waste as a source of energy. Anaerobic digestion involves organic-matter decomposition under anoxic conditions by a microbial consortium, obtaining a source of renewable energy (biogas), mainly constituted of a mixture of carbon dioxide (CO2, 25–45 percent), methane (CH4, 55–75 percent), and the digested substrate (digestate). The direct application of digestate into agricultural soils presents several problems. These include agronomic (low concentration of nutrients, high salinity, etc.), economic (cost of transport and handling), and environmental issues (gaseous emissions, nutrient leaching, and pathogen spread). However, it is possible to obtain quality compost from the solid fraction of digestate, and the compost obtained can have good properties for use as container growing medium or for crop production. In this work, an optimized procedure has been developed for composting the solid phase of a digestate obtained from a continuous, anaerobic codigestion of cattle slurry with 84 percent of cattle manure, 7.4 percent of a mixture of maize/silage, and 8.6 percent of peach-juice pulp (fresh-mass basis). The experiment was designed to optimize pH, carbon (C) / nitrogen (N) ratio, and moisture values in order to maximize self-heating activity, using Dewar self-heating tests. A factorial optimization of moisture and C/N ratio was carried out. In the best moisture-C/N ratio treatment, pH optimization was also developed. To predict the optimum conditions of the studied residue related to the increase of temperature per dry matter, a multiple correlation analysis based on moisture, C/N ratio, and pH was developed, which explained 80 percent of the variance in this experiment.

The aim of the present article is to show the possibilities of chemometric tools and the parallel factor analysis (PARAFAC) model, as well as to understand the complexities of the fluorescence emission-excitation matrix (EEM) of water-soluble organic matter (WSOM) extracted from sewage sludge samples obtained with different origins and stabilization procedures. The variation in the composition of WSOM in the different sewage sludge samples could be correlated with the conditions of stabilization; therefore, the use of fluorescence spectroscopy to monitor these changes can be a useful tool to optimize the management of this residual flux, avoiding environmental pollution. However, the “contour density” EEM maps obtained with fluorescence present continuous spectra with different peaks, valleys, and shoulders where manual peak picking can be complicated and subjective, especially in complex matrixes such as sewage sludge. With the PARAFAC algorithm, it is possible to resolve the emission and excitation spectra of the different fluorescence components present in the samples and their contribution to the total fluorescence. Also, the contribution (scores) of the different fluorophors can be coupled with another chemometric tool to provide an effective classification method using the stabilization conditions of sewage sludge as main criterion. In this study, a wide survey of sewage sludge samples (287) was characterized by fluorescence emission-excitation matrix. The final molecular composition of the sewage sludge samples was not related to the stabilization (aerobic vs anaerobic) treatments. However, a sewage sludge classification based on a combined spectroscopic-chemometric approach was obtained, which could be used for the optimization of sewage sludge use in agriculture, minimizing the environmental risks.

The objective of this work was to study the co-composting process of wastes from the winery and distillery industry with animal manures, using the classical chemical methods traditionally used in composting studies together with advanced instrumental methods (thermal analysis, FT-IR and CPMAS 13C NMR techniques), to evaluate the development of the process and the quality of the end-products obtained. For this, three piles were elaborated by the turning composting system, using as raw materials winery-distillery wastes (grape marc and exhausted grape marc) and animal manures (cattle manure and poultry manure). The classical analytical methods showed a suitable development of the process in all the piles, but these techniques were ineffective to study the humification process during the composting of this type of materials. However, their combination with the advanced instrumental techniques clearly provided more information regarding the turnover of the organic matter pools during the composting process of these materials. Thermal analysis allowed to estimate the degradability of the remaining material and to assess qualitatively the rate of OM stabilization and recalcitrant C in the compost samples, based on the energy required to achieve the same mass losses. FT-IR spectra mainly showed variations between piles and time of sampling in the bands associated to complex organic compounds (mainly at 1420 and 1540 cm-1) and to nitrate and inorganic components (at 875 and 1384 cm-1, respectively), indicating composted material stability and maturity; while CPMAS 13C NMR provided semi-quantitatively partition of C compounds and structures during the process, being especially interesting their variation to evaluate the biotransformation of each C pool, especially in the comparison of recalcitrant C vs labile C pools, such as Alkyl /O-Alkyl ratio.