ABSTRACT Polymer flooding consists of injecting polymer-augmented water into the reservoir to control the water-oil mobility ratio, resulting in an increase in the volumetric sweep efficiency compared to water flooding. Synthetic polymers (polyacrylamides) and biopolymers (scleroglucan, xanthan gum, schizophyllan) are the two families of polymers usually evaluated for enhanced oil recovery (EOR). Scleroglucan (SG) is resistant to electrolytes, hydrolysis, pH (3-10) and temperature (30-100°C) and has remarkable rheological properties, but it is quite susceptible to microbiological degradation. The primary objective of this study was to evaluate the biodegradation of SG in the injection and production processes and its aquatic toxicity. The anaerobic biodegradation of the SG solutions was determined through the viscosity changes of the solutions, while the aerobic biodegradation was calculated with the changes in the SG concentration. It was observed that the viscosity reduction of the SG solution was 30% and the SG concentration decreased from 100 ppm to 52 ppm because bacteria can metabolize the biopolymer. Daphnia pulex, Scenedesmus acutus and Oreochromis sp. were the organisms used in the ecotoxicological assays of the SG solutions. The acute ecotoxicological bioassays showed that there was no evidence of acute deleterious effects of SG on any of the three organisms. From the chronic ecotoxicological bioassays, it was concluded that there was no effect of SG on the mortality of Daphnia pulex, regardless of the tested SG concentration.

RESUMEN La inyección de polímeros en el yacimiento es usada para incrementar la viscosidad del agua para controlar la relación de movilidad agua-petróleo, lo que resulta en un aumento en la eficiencia de barrido volumétrico, en comparación con el proceso de inyección de agua. Los polímeros sintéticos (poliacrilamidas) y biopolímeros (escleroglucano, goma xantana, esquizofilano) son las dos familias de polímeros más usadas para la recuperación mejorada de petróleo (EOR). El escleroglucano (SG) es resistente a electrolitos, hidrólisis, pH (3- 10) y temperatura (30-100°C) y tiene excelentes propiedades reológicas, pero es susceptible a la degradación microbiana. El objetivo principal de este estudio fue evaluar la biodegradación de SG durante su inyección y producción y su toxicidad acuática. La biodegradación anaeróbica de las soluciones SG se determinó a través de los cambios de viscosidad de las soluciones, mientras que la biodegradación aeróbica fue calculada por los cambios en la concentración de SG. Se observó que la reducción de la viscosidad de la solución SG fue del 30% y que la concentración de SG disminuyó de 100 a 52 ppm, porque las bacterias pueden metabolizar el biopolímero. Daphnia pulex, Scenedesmus acutus y Oreochromis sp. fueron los organismos utilizados en los ensayos ecotoxicológicos de las soluciones SG. Los bioensayos ecotoxicológicos agudos mostraron que no hay evidencia de efectos nocivos agudos del SG en ninguno de los tres organismos. A partir de los bioensayos ecotoxicológicos crónicos se concluyó que no hay efecto del SG en la mortalidad de Daphnia pulex, a las concentraciones de SG evaluadas.

Abstract Background: The assessment of oocyte quality is, nowadays, a major challenge in aquaculture, oocyte cryopreservation, and environmental science. Oocyte quality is a determining factor in fertilization and embryo development; however, there is still a lack of rapid and sensitive cellular markers for its assessment. Currently, its estimation is pre-dominantly based on morphological analysis, which is subjective and does not consistently reflect the developmental competence of the oocytes. Despite several recent studies investigating molecular markers related to oocyte quality, methods currently available for their determination pose various technical challenges and limitations. In this study, we developed a novel approach based on fluorescence spectroscopy to assess different intrinsic physiological parameters that can be employed to evaluate egg quality in marine invertebrates that are widely used as animal models such as sea urchins and mussels. Results: Different physiological parameters, such as viability, mitochondrial activity, intracellular ROS levels, plasma membrane lipid peroxidation, and intracellular pH, for egg quality evaluation have been successfully assessed in sea urchins and mussels by using specific fluorescent dyes and detecting the fluorescent signals in eggs through fluorescence spectroscopy. Conclusions: Based on our findings, we propose these physiological markers as useful predictors of egg quality in marine invertebrates; they can be estimated rapidly, selectively, and sensitively by employing this novel approach, which, due to the speed of analysis, the low cost, and easy use can be considered a powerful analytical tool for the egg quality assessment.

Resumen La cocristalización con sacarosa se ha utilizado para obtener productos con mejores propiedades físicas, como solubilidad, humectabilidad, hidratación y estabilidad, así como para preservar los componentes activos presentes en la mayoría de las futas. El objetivo de este trabajo fue determinar el efecto del pH y concentración de pulpa de guayaba (Psidium guajava L) y jugo de maracuyá (Passiflora edulis, en adelante concentración de fruta), sobre la humedad, la densidad aparente, la solubilidad, el ángulo de reposo, la higroscopicidad y la cinética de cocristalización de productos cocristalizados de jugo de maracuyá y pulpa de guayaba. Se prepararon los cocristalizados con jarabe de sacarosa a 70 °Brix, pulpa de guayaba concentrada a 18 °Brix y el jugo de maracuyá a 40 °Brix. Para concentrar las mezclas y prepararlas para la cocristalización se utilizó un evaporador rotativo Heidolph D-91126 HB y un controlador de vacío Heidolph DC1/1HO. La cinética de cocristalización se evaluó utilizando un reómetro TA Instrument AR 1500ex, determinando la viscosidad compleja en el tiempo, a través de una rampa de temperatura de 80 °C a 15 °C a 1 Hz, descendiendo 6,5 °C/min, ajustando los datos experimentales a un modelo empírico. El aumentar la concentración de fruta añadida en el proceso, aumentan el tiempo de cristalización y la humedad final del producto, y disminuye su solubilidad. La velocidad de cocristalización se ve favorecida por la menor concentración de fruta, presentándose una mayor velocidad de cristalización para los cocristalizados de pulpa de guayaba que en los de jugo de maracuyá.

Abstract Co-crystallization with sucrose has been used to obtain products with better physical properties (such as solubility, wettability, hydration, and stability) and to preserve the active components present in most fruits. The objective of this study was to determine the effect of the pH and concentration of guava (Psidium guajava L) pulp and passion fruit (Passiflora edulis) juice (both referred to as fruit concentration) on the moisture, apparent density, solubility, angle of repose, hygroscopicity, and co-crystallization kinetics of co-crystallized passion fruit juice and guava pulp products. The co-crystallized products were prepared with sucrose syrup at 70 °Brix, concentrated guava pulp at 18 °Brix, and passion fruit juice at 40 °Brix. A Heidolph D-91126 HB Rotary-evaporator and a Heidolph DC1/1HO Vacuum Controller were used to concentrate the mixtures and prepare them for co-crystallization. The co-crystallization kinetics was evaluated using a TA Instrument AR 1500ex rheometer, thus determining complex viscosity over time using a temperature ramp from 80 to 15 °C at 1 Hz, descending at 6.5 °C/min. Then, the experimental data were fitted to an empirical model. Our results show that increasing the fruit concentration added in the process extends the crystallization time, increases the final moisture of the product, and decreases its solubility. The co-crystallization rate was favored by the lowest fruit concentration, and a higher crystallization rate was observed in the guava pulp than in the passion fruit juice (two co-crystallized products).

RESUMO Óleo essencial de orégano (OEO) apresenta propriedades antimicrobianas e antioxidantes. Os compostos bioativos do OEO são voláteis. Portanto, a encapsulação ajuda a proteger a atividade dos compostos quando expostos a condições danosas, como alta (ou baixa) temperatura, luz e oxigênio. A encapsulação também auxilia a melhorar a dispersibilidade do componente em meios aquosos, facilitando sua aplicação em produtos alimentícios formulados. Nós estudamos a cinética de liberação do OEO microencapsulado por coacervação complexa entre gelatina e goma arábica, focando a influência das propriedades físico-químicas do meio aquoso de liberação (temperatura (4, 25 e 30 ºC), força iônica (0, 0.5, 1.0 e 1.5 M) e pH (3.8, 4.2 e 4.8)). Suas capacidades de agirem como gatilhos de liberação também foram investigadas. Altas taxas de OEO liberado ocorreram nos meios com elevada força iônica (74% liberado em 5 h), alto pH (78% liberado em 7 h) e baixa temperatura (71% liberado em 7 h). Em meios com temperatura acima de 30 ºC e pH 3.8, a estrutura coacervada foi desintegrada. Um delineamento de faces centradas (DFC) baseado em 17 amostras foi construído e um modelo empírico desenvolvido para prever as condições de máxima liberação. A maior porcentagem de óleo (atingindo até 85%) é liberada em longos períodos de tempo (em média 7 h) sem causar danos às microcápsulas. O modelo de Peppas mostrou o melhor ajuste para todos perfis de liberação, com R² > 0,86 e erro residual médio < 6%, indicando o domínio da difusão de Fick na liberação de OEO.

ABSTRACT Oregano essential oil (OEO) exhibits antimicrobial and antioxidant properties. The bioactive compounds of OEO are volatile. Thus, encapsulation helps in protecting the activity of the compound when exposed to harmful conditions such as high (or low) temperature, light, and oxygen. Encapsulation also helps to improve the dispersibility of the compound in an aqueous medium, facilitating its application in formulated food products. We studied the release kinetics of OEO microencapsulated by gelatin/gum. Arabic complex coacervation was assessed, focusing on the influence of the physicochemical properties of the aqueous release medium (temperature (4, 25, and 30 ºC), ionic strength (0, 0.5, 1.0, and 1.5 M), and pH (3.8, 4.2, and 4.8)). Their capacity to act as release triggers was also investigated. High OEO release rates were recorded in the media with high ionic strengths (74% release in 5 h), high pH (78% release in 7 h), and low temperature (71% release in 7 h). In media at a temperature above 30 ºC and pH 3.8, the coacervated structure was disintegrated. A centered face experimental design (CFD) based on 17 samples was constructed, and an empirical model was developed to predict the maximum release conditions. The highest percentage of oil (reaching up to approximately 85%) is released over longer periods of time (7 h on an average) without damaging the integrity of the microcapsule. Peppas’ model showed the best fitting for all release profiles, with R² > 0.86 and relative average residual error < 6%, indicating the domain of Fickian diffusion during OEO release.

RESUMEN La inyección de polímeros representa la recuperación mejorada química de petróleo (CEOR, de sus siglas en inglés) más común utilizada a escala comercial. En este proceso, las soluciones poliméricas (generalmente poliacrilamida hidrolizada - HPAM) se inyectan para mejorar la relación de movilidad aceite/agua (M). Sin embargo, debido a las degradaciones mecánicas, químicas, biológicas y térmicas, pueden producirse pérdidas de viscosidad del polímero, lo que afecta negativamente la eficiencia de barrido de aceite. En este caso, los biopolímeros surgen como candidatos prometedores en aplicaciones EOR que tienen características estructurales especiales que les permiten exhibir una excelente estabilidad en ambientes hostiles con altas temperaturas, fuerzas iónicas y esfuerzos de corte. Este trabajo presenta la evaluación de laboratorio de Escleroglucano (SG) y una poliacrilamida sulfonada comercial (ATBS) en salmuera sintética representativa de un campo de petróleo pesado colombiano. También se evaluaron los efectos de la fuerza iónica, el pH, la temperatura y los efectos de degradación por esfuerzo de corte sobre la viscosidad del polímero. Para SG, los resultados reflejan su tolerancia a altas salinidades (0-5% en peso), fuerzas iónicas (Na+, K+, Ca2+ y Mg2+), velocidades de corte (0-275,000 s-1), temperaturas (30, 50, 80 y 10 °C) y variaciones de pH (3-10). El biopolímero fue capaz de preservar sus propiedades viscosas y estabilidad después de la afectación de estas variables. Finalmente, la viscosidad objetivo (establecida en 17 cP) se logró con una concentración más baja (2.7 veces) en comparación con el polímero ATBS evaluado.

ABSTRACT Polymer flooding represents the most common chemical enhanced oil recovery (CEOR) method used at commercial scale. In this process, the polymeric solutions (generally hydrolyzed polyacrylamide - HPAM) are injected to improve the oil/water mobility ratio (M). However, due to mechanical, chemical, bio, and thermal degradation, polymer viscosity losses can occur, causing a negative impact on oil sweep efficiency. In this case, biopolymers seem to be promising candidates in EOR applications with special structural characteristics, which result in excellent stability in harsh environments with high temperatures, ionic forces, and shear stresses. This paper presents the laboratory evaluation of Scleroglucan (SG) and a commercial sulfonated polyacrylamide (ATBS) in synthetic brine, representative of a Colombian heavy-oil field. The effects of ionic strength, pH, temperature, and shear degradation effects on polymer viscosity were also evaluated. For SG, the results reflect its tolerance to high salinities (0-5%wt), ionic strengths (Na+, K+, Ca2+, and Mg2+), shear rates (0-275,000 s-1), temperatures (30, 50, 80 and 100 °C), and pH variations (3-10). The biopolymer was capable of preserving its viscous properties and stability after of the effect of these variables. Finally, the target viscosity (set as 17 cp) was achieved with a lower concentration (2.7 times) than the ATBS polymer tested.

Abstract The shelf life (SL) of freshly extracted sugarcane juice is limited to a few hours, and the use of hurdle technology is a strategy to ensure its safety and stability. The SL of standardized cane juice (19.4 °Brix, 0.085% acidity and pH 4.35), pasteurized at 95 °C/30 s and stored under refrigeration, was estimated. Ideal (4 °C), commercial (8 °C) and abusive (12 °C) conditions were tested. Microbiological and sensory assays were carried out on the newly processed juice (time zero) and overtime to estimate the SL. Counts of psychrotrophic bacteria and molds and yeasts equivalent to 4 and 3 logCFU mL-1, respectively, were set as acceptable maximum levels to establish the SL. Average scores greater than 5 (in the 9-point hedonic scale) and percentages of approval greater than 60% were both used as threshold values for juice´s appearance and flavor. The juice´s SL stored at 4, 8 and 12 °C were 94, 74 and 26 days, respectively. The combination of multiple technologies applied in this study was effective in obtaining a product with high sensory acceptance and a SL compatible with possible demands of the consumer market.

Abstract: The Neotropical otter is a predator located in the upper trophic level; its geographical distribution stretches from northern Mexico to central Argentina. It lives in river banks, where it rests, plays, marks its territory, cleans its fur and breeds its offspring. Lontra longicaudis is sensitive to alterations in the habitat, either by the degradation of river bank environments and by pollution of water bodies; hence, it is considered as an indicator of the degradation of aquatic ecosystems. This species is currently included in the threatened species category according to NOM-059-SEMARNAT-2010. The aim of this work is to characterize the habitat and determine the abundance of the Neotropical otter in the upper part of San Diego River, to assess whether the sea otter population abundance is directly related on the characteristics of the habitat and the seasonal dynamics. The monitoring was carried out over two years (2012-2013). Eight kilometers along the river were sampled considering 3 segments of equal length, since preliminary visits revealed that these had distinctive physical and environmental characteristics. The physicochemical parameters of water were measured, plant species growing along the river bank were identified, 266 samples of feces were collected, and otter relative abundance was estimated. Segment 1 showed an acid water pH, with low temperatures and plant species of the genera Pinus, Quercus and Juniperus along the river banks; the second segment showed a neutral pH, with higher temperatures, and scarce riparian vegetation; the third segment again displayed riparian vegetation, with warm water and near-neutral pH. The relative abundance determined for the otter population averaged 0.46 otters/km. A model for predicting otter abundance was obtained, which yielded a prediction error of ± 0.27 otters/km. The characteristics of the habitat associated with otters in this area were similar to those described by other authors for other parts of the country, namely a neutral pH, clean oxygen-rich waters, low water temperature in the upper portions of the river, presence of riparian vegetation, with stretches of rapids and shallow areas with pools of slow-flowing, deep water. Separately, the abundance of otters found in this case lied within a range that differed from the one reported by other authors, which varies between 0.21 and 1.22 otters/km; again, this was not a fixed value, but varied over the sampling period: it decreased in the rainy season and rose in the dry season. The abundance-habitat relationship model showed an acceptable fit; however, the most significant variables were total dissolved solids, pH, flow zone and depth. This study made possible to determine the current status of the otter and the conditions of its habitat in this area; however, further studies are needed to gain a detailed understanding on the species to support decision-making and implement conservation actions.

Resumen: La nutria neotropical es un depredador ubicado en el nivel trófico superior, su distribución geográfica abarca desde el norte de México hasta la zona central de Argentina. Habita en las riberas de los ríos, donde puede realizar actividades de descanso, juego, marcaje de territorio, limpieza de pelaje y cría de cachorros. Lontra longicaudis es sensible a cambios en su hábitat, ya sea por la degradación de los ambientes de ribera como la contaminación de los cuerpos de agua, por lo que se le considera un indicador de la degradación de los ecosistemas acuáticos. Actualmente, se encuentra dentro de la categoría de amenazada de acuerdo a la NOM-059-SEMARNAT-2010. El objetivo del presente trabajo es caracterizar el hábitat y determinar la abundancia de la nutria neotropical en la parte alta del Río San Diego, para conocer si la abundancia poblacional de la nutria depende directamente de las características del hábitat y de la dinámica estacional. El monitoreo se realizó durante dos años (2012-2013), se muestrearon 8 kilómetros sobre el río, los cuales se dividieron en 3 segmentos de igual tamaño, ya que en base a recorridos preliminares, se pudo observar de manera general que presentaban características físicas y ambientales diferentes. Se midieron los parámetros fisicoquímicos del agua, se identificaron las especies de flora a las orillas del rio, se colectaron 266 heces y se obtuvo la abundancia relativa de la nutria. El segmento 1 presentó un pH del agua ácido, con temperaturas frías y especies de los géneros: Pinus, Quercus y Juniperus sobre las orillas del cauce; en el segundo segmento se encontró un pH neutro, con temperaturas más cálidas, se observó poca presencia de vegetación de ribera; en el tercer segmento nuevamente se observó vegetación ribereña, con aguas cálidas y un pH próximo a neutro. Se determinó una abundancia relativa promedio de la población de 0.46 nutrias/km. Se obtuvo un modelo para la predicción de abundancia de nutrias con un error de predicción de ± 0.27 nutrias/km. Las características del hábitat de la nutria en esta zona coinciden con lo descrito por otros autores para otros lugares del país, con pH neutro, aguas limpias con alto valores de oxígeno disuelto, con temperaturas del agua mayormente frías en las partes altas, presencia de vegetación ribereña, con tramos de rápidos y baja profundidad y zonas con pozas de aguas lentas y profundas. Por otra parte, la abundancia de la nutria obtenida se encontró dentro de un rango de diferentes valores obtenidos por otros autores, el cual varía de entre los 0.21 nutria/km a 1.22 nutrias/km, pero igualmente este valor no fue fijo, sino que varió dentro del periodo de muestreo, para este caso, en la temporada de lluvias disminuyó y en temporada de secas aumentó. El modelo relación abundancia-hábitat presentó ajustes aceptables; sin embargo, las variables más significativas fueron el total de sólidos disueltos, el pH, la zona de flujo y la profundidad. Este estudio permitió conocer la situación actual de la nutria en esta área y las condiciones de su hábitat; no obstante, es necesario realizar más estudios que generen mayor conocimiento de esta especie y poder tomar decisiones e implementar acciones para su conservación.

Evaluation of fungal diversity restoration in an afforestation of Polylepis australis (Rosaceae): a case study: Polylepis australis forest had been significantly disturbed and afforestation is an alternative to restore these ecosystems. The aim of this study is to evaluate the restoration of the fungal community in P. australis afforestation. Our hypothesis is that the fungal community varies between forest situations: high degraded, mature forest, and restored forest. Fungal variables (richness, abundance and evenness of macromicetes) were compared between a native area, an afforestation and a degraded land. To this end, 15 plots of 5x5 m were established and five of them were sampled in each season. Macromicetes fruiting bodies were collected and classified into different morpho-taxonomical groups. Principal Components Analyses and correlation analyses between the fungal variables and the plot's structure were performed as well as correlation analysis between the fungal variables and soil chemical variables. Richness, abundance and evenness were significantly higher in the native area, intermediate in the afforestation and lower in the degraded land. The native area's plots showed high tree cover, the afforestation´s plots high graminoid and young trees cover, and the degraded land's plots high forbs cover. Values of fungal variables were higher at higher tree cover and were positively correlated with soil phosphorus content and pH. The results show that, after 12 years of afforestation with P. australis, the fungal diversity in that ecosystem is higher than the observed in reference degraded land but is far from the observed in a native area. It can be hypothesized that fungi are sensitive bioindicators of forest degradation and restoration.

Los bosques de Polylepis australis han sido muy disturbados y la reforestación es una alternativa para restaurar esos ecosistemas. El objetivo del presente estudio es evaluar la restauración de la comunidad fúngica en un bosque de P. australis reforestado. Nuestra hipótesis de trabajo es que la comunidad fúngica se modifica en concordancia con las situaciones del bosque: alta degradación, bosque natural maduro y bosque restaurado. Se compararon variables fúngicas (riqueza, abundancia y equitatividad de macromicetes) de un área nativa, de un área degradada y reforestada y de un área degradada sin reforestación. Para ello se establecieron 15 parcelas de 5x5 m y se muestrearon cinco por estación. Se recolectaron las fructificaciones de macromicetes, y luego se las clasificó en grupos morfo-taxonómicos. Se hicieron análisis de componentes principales y de correlación entre las variables fúngicas y la estructura vegetal, y análisis de correlación entre las variables fúngicas y las variables químicas del suelo. La riqueza, la abundancia y la equitatividad fueron significativamente mayores en el área nativa, intermedias en el área reforestada y menores en el área degradada. Las parcelas del área nativa se caracterizaron por una alta cobertura de árboles maduros, las del área reforestada por graminoides y árboles jóvenes y las del área degradada por herbáceas latifoliadas. Las tres variables fúngicas fueron máximas a mayor cobertura arbórea y correlacionaron positivamente con el fósforo y pH del suelo. Los resultados muestran que 12 años después de que un área degradada fuera reforestada con P. australis, la diversidad fúngica es mayor que la de un área degradada, pero está lejos de alcanzar los niveles del área nativa. Se postula que los hongos serían bioindicadores sensibles a la degradación y la restauración de los bosques.

Vinte e dois cordeiros machos não castrados, Dorper x Santa Inês, com aproximadamente 90 dias de idade e peso vivo médio inicial de 27,0±4,4kg, foram alimentados com uma dieta com elevada proporção de concentrado com 20% de pelete proteico-mineral (Grano Entero(r)), 5% de feno de capim coast-cross e 75% de milho, na forma de milho grão inteiro (MGI), milho grão moído (MGM) ou milho grão úmido (MGU), para avaliação de desempenho no confinamento por um período de 14 dias de adaptação às dietas e às instalações e de 65 dias de confinamento. Em seguida, os animais foram abatidos com peso vivo médio final (PVF) de 47,97±5,13kg e o conteúdo gástrico foi avaliado para quantificação de protozoários, e foi realizada avaliação papilar. O delineamento experimental foi o de blocos casualizados. Não houve diferença entre os tratamentos (P&gt;0,05) quanto ao ganho de peso médio diário, eficiência alimentar, ingestão diária de matéria seca, características da carcaça e da carne. Os animais tratados com MGI tiveram maior conteúdo gástrico, menor pH ruminal, maior AP (% da superfície de absorção) e maior área papilar em comparação com os outros tratamentos. Os animais tratados com MGI tiveram melhores resultados para o peso final, mas para os demais parametros estudados não foi observada diferença.

Twenty-two males not neutered, Dorper x St. Agnes, with approximately 90 days of age and average live weight of 27.0±4.4kg were fed with a diet wich contained high concentrate with 20% protein pellet-mineral (Grano Entero (r)), 5% grass hay coast-cross and 75% corn in the form of whole kernel corn (MGI), ground corn grain (MGM) or high moisture corn (MGU) for performance evaluation in confinement for a period of 14 days of adaptation to the diets and facilities and 65 days of confinement. Then the animals were slaughtered at average final weight (PVF) of 47.97±5.13kg and gastric content was evaluated for quantification of protozoa, and a papillary review was conducted. The experimental design was in randomized blocks. There was no difference between treatments (P&gt;0.05) for average daily weight gain, feed efficiency, daily dry matter intake, carcass characteristics and meat. MGI-treated animals had higher gastric contents, the lower ruminal pH greater AP (% of surface absorption) and the larger papillary area was compared with other treatments. Animals treated with MGI had better results for the final weight gain, but for the other parameters studied, no difference was observed.

Se propone la adsorción de Pb (II) usando bagazo de palma tratado químicamente con ácido cítrico, se elige este material por ser un desecho agroindustrial ampliamente disponible en la región Caribe colombiana. Los experimentos fueron llevados a cabo en sistema batch en solución acuosa de plomo a una concentración de 100 ppm. La determinación de la concentración de metal al final del proceso se midió por absorción atómica. La caracterización de los materiales adsorbentes usados se hizo por FTIR encontrando que los grupos hidroxilos y carboxílicos son los principales responsables de la capacidad de adsorción. Además, fue encontrado que el pH es el factor de mayor incidencia en el proceso, siendo el de 6 el valor óptimo. Por otra parte, se encontró que el Pb (II) presenta una sorción rápida durante los primeros 10 minutos, además el modelo de Elovich fue el de mejor ajuste. La capacidad máxima de adsorción según la isoterma de Langmuir fue de 162 y 451 mg/g para el bagazo sin modificar y modificado respectivamente, estableciendo que la modificación fue altamente eficiente.

It was studied the adsorption of Pb (II) using palm bagasse chemically treated with citric acid. This material is chosen due to is an available waste in the Colombian Caribbean region. The experiments were carried out in batch system in aqueous solution of lead at a concentration of 100 ppm. The determination of the heavy concentration at the end of the process was measured by atomic absorption. The characterization of adsorbent materials used was carry out using FTIR. It was found that the hydroxyl and carboxyl groups are mainly responsible of adsorption capacities. Furthermore, it was found that the pH is the most prevalent factor in the process. The optimum value was 6. Moreover, it was found that the Pb (II) exhibits rapid sorption during the first 10 minutes. The process was better fitted by the Elovich model. The maximum adsorption capacity according to Langmuir isotherm was 162 and 451 mg/g for unmodified and modified bagasse respectively. It was established that the chemical treatment was highly efficient.

Las técnicas de espectrometría y el análisis de las diatomeas permitieron excelentes ajustes para la estimación de la variación de las concentraciones de materia orgánica mediante el método de pérdida por ignición y la determinación de fósforo total y nitrógeno total Kjeldahl durante el tiempo de operación de los embalses de La Fe (37 años), Ríogrande II (21 años) y Porce II (9 años), localizados en Antioquia, Colombia. Los cambios en la paleo-geoquímica de los embalses no se acercaron al comportamiento esperado en los lagos, es decir, a una disminución exponencial en relación con la profundidad, lo cual se debe, en parte, a factores como la diagénesis tardía del sedimento y a la operación o manejo de los embalses. Sin embargo, las diatomeas presentes en el sedimento, así como la diversidad y el promedio anual del pH en la columna de agua, mostraron cambios significativos con respecto al llenado inicial del embalse y hasta el 2010 (año de recolección de los datos). En los embalses de La Fe y Ríogrande II se observó una disminución en la buena calidad inicial del agua, mientras que en Porce II estos indicadores mostraron una permanente eutrofización del sistema.

We present the results of a multiproxy reconstruction of the variation of organic matter using the loss-on-ignition method, and total phosphorus and Kjeldahl nitrogen during the operation of La Fe (37 years), Ríogrande II ( 21 years) and Porce II (9 years) reservoirs in Antioquia, Colombia, based on the analysis of diatoms and using near- infrared spectroscopy. Changes in reservoir paleo-geochemistry did not approach the expected behavior for lakes, i.e., an exponential decrease with depth, due in part to factors such as a late diagenesis and the management of the reservoirs. However, diatoms present in the sediment, along with diversity and the annual average pH of the water column, showed significant changes from the initial filling of the reservoirs until 2010 (year in which the data were collected). In La Fe and Ríogrande II reservoirs, a decrease in water quality was observed, whereas in Porce II reservoir these indicators showed the continuing eutrophication of the system.

Insufficient glycogen content in bovine muscle at slaughter produces meat with high final pH (> 5.8) which is undesirable. The objective of this study was to determine through biopsies the live changes in muscle glycogen concentration (MGC) of housed steers fed on hay or hay plus energy concentrate for 30 d and then determine the effect of food deprivation (fasting) for 24 h on the same variable. Ten steers of similar age, weight, and phenotypic characteristics were housed in individual pens and randomly assigned to two feeding treatments: ad libitum hay only (H, n = 5) and ad libitum hay plus flaked corn (Zea mays L.) (HC, n = 5). Biopsies (B) were taken from the Longissimus dorsi muscle at four occasions: the day before the start of experiment (B0), after 15 d (Bl), after 30 d (B2), and fasted for 24 h after B2 (B3). Before each biopsy, steers were sedated with xylazine (0.03 mL kg-1) and lidocaine was applied locally; samples were frozen in liquid nitrogen to determine MGC. Results showed a significant (P < 0.05) effect of diet treatment (HC > H) and also of time (B2 > Bl) on MGC; the decrease in MGC of steers due to fasting (B2 vs. B3) was not significant (P > 0.05). It was concluded that muscle biopsies allowed to detect a difference in the increase of MGC in steers fed an energy supplementation compared to steers fed hay only, and that fasting for 24 h tended to reduce MGC in both groups.

In order to explore the capacity of behavioural tests to predict the incidence of high pH meat (dark cutting) in commercial setting, we assessed the relationship between behavioural reactivity, physiological parameters and meat quality in steers. Fourty-two steers were weighed individually in a scale (2.5x3x2.5m) to assess two behavioural parameters: crush test and exit velocity. Repeatability of the behavioural responses during 3 weighing events was calculated and a consistency scale was created to determine consistency of the parameters. Blood samples were collected from each steer after the second crush test and at bleeding, then analyzed for serum cortisol. Bruising and pH were registered after slaughter on the carcasses. Crush score was highly consistent (r = 0.81-0.87) and exit velocity moderately consistent (r = 0.44-0.60), however individual differences were detected in the "acclimation" and "sensitization" to the test through time. Higher crush score was associated with higher on farm cortisol concentration. Steers producing carcasses with multiple bruises (3-4) had a higher serum cortisol concentration at bleeding (P < 0.05) than steers with less carcass bruising. Behavioural parameters, carcass bruising and meat pH were not statistically associated. We conclude that it is important to evaluate behavioural reactivity using serial tests and we recommend further exploration on the capacity of reactivity tests to detect differences in reactivity that can be reflected in differences in meat quality parameters.

Con el motivo de indagar en la predicción de la incidencia de pH elevado (corte oscuro) en base a pruebas conductuales aplicables en situaciones comerciales, se evaluó la relación entre la reactividad conductual y parámetros fisiológicos y de calidad de carne en novillos. Cuarenta y dos novillos fueron pesados individualmente en una báscula de 2,5x3x2,5m para evaluar dos parámetros conductuales: el grado de reactividad y la velocidad de salida. Para determinar la consistencia de las respuestas, se calculó la repetibilidad de las respuestas durante tres pesajes y se creó una escala cualitativa de consistencia. La concentración de cortisol sérico fue determinada post-pesaje en el predio y al desangrado, las contusiones y el pH fueron registrados en la canal. El grado de reactividad fue altamente repetible (r = 0,81-0,87) y la velocidad de salida medianamente repetible (r = 0,44-0,60), sin embargo, se detectaron diferencias individuales en la "habituación" y "sensibilización" a la prueba. Los animales con mayor grado de reactividad tuvieron mayores concentraciones de cortisol sérico en el predio. No hubo asociación entre las respuestas conductuales, las contusiones en la canal y el pH final de la carne. Novillos cuyas canales presentaron múltiples contusiones (3-4) tuvieron una concentración de cortisol promedio al desangrado significativamente (P < 0,05) más alta que novillos con menos contusiones en la canal. Se concluye que la reactividad debe ser medida en forma seriada y se recomienda indagar más sobre la capacidad de las pruebas de reactividad para detectar diferencias en reactividad que puedan reflejarse en diferencias en parámetros de calidad de la carne.

This study compared the technological quality of twelve muscles of llama that were raised in a grazing system. The llamas (n=10) were slaughtered using Bolivian standard procedures. Carcasses were stored for 24 h in a cold room (4 ºC). Muscles were removed from the left side of each carcass in the slaughter house. Five steaks (2.54 cm thick) were cut from each muscle. In each muscle was determined pH, colour (L*, a*, b*), water holding capacity (WHC) and Warner-Bratzler shear-force (WBSF). No statistical difference was found in pH between muscles. Values of L* (lightness) and b* (tenor of yellow) in L. thoracis, L. lumborum and Semimembranosus were higher than those in Triceps brachii and Psoas major (p<0.05). The cooking loss percentage was lower in Infraspinatus and Longissimus thoracis (p<0.05). The WBSF value in the Semimembranosus, Semitendinosus, Quadriceps femoris and Biceps femoris muscles was higher (p<0.05) and in Infraspinatus was the lowest (p<0.05). Tenderness (WBSF), colour, and water holding capacity varied between muscles.

Se compararon las características tecnológicas de doce músculos de llamas que fueron criadas al pastoreo. Las llamas (n=10) fueron faenadas bajo procedimientos estándares de Bolivia. Las canales fueron refrigeradas durante 24 horas a 4 ºC. Los músculos fueron removidos de cada canal después del desposte. Cinco bifes de 2.54 cm de espesor fueron cortados de cada músculo. En cada músculo se determinó el pH24, color (L*, a*, b*), capacidad de retención de agua y fuerza de corte Warner-Bratzler (WBSF). No se observaron diferencias estadísticas en el pH entre los músculos. Los valores de L* (luminosidad) y b* (tenor de amarrillo) de los músculos L. thoracis, L. lumborum y Semimembranosus fueron mayores que en Triceps brachii y Psoas major (p<0.05). El porcentaje de pérdida por cocción fue menor en los músculos Infraspinatus y Longissimus thoracis (p<0.05). El valor WBSF de los músculos Semimembranosus, Semitendinosus, Quadriceps femoris y Biceps femoris fue mayor (p<0.05) y del músculo Infraspinatus fue el más bajo (p<0.05). La textura (WBSF), color y capacidad de retención de agua variaron entre los músculos.

The aim of this study was to determine the effects of a high energy supplementation based on flaked corn and of the duration of this supplementation, on the concentrations of muscle and liver glycogen and on carcass meat quality characteristics related to dark cutting in steers grazing pasture during the fattening stage. Seventy two steers of dairy origin (Red and Black Friesians), with an initial live weight between 460 and 520 kg were used. Within each treatment (36 steers with and 36 without high energy supplementation), the steers were assigned at random to one of four time lengths of supplementation (7, 14, 21 and 28 days, 9 steers each). The statystical model used was completely at random with a 2x4 factorial (2 treatments and 4 time lengths of treatment); the interaction diet x duration of the supplementation, the age by dental chronometry and the initial weight of the steers as a covariable were also included. In general, the supplementation resulted in better carcass quality characteristics such as weight, proportional dressing yield, loin eye area and fat cover. Although mean concentrations of muscle glycogen did not differ between treatments, the high energy supplementation reduced the presentation of dark cutters as evaluated through color and pH in Longissimus thoracis muscle.

El objetivo de esta investigación fue determinar el efecto de una suplementación con concentrado energético, en base a maíz roleado, y de la duración de la suplementación durante la etapa final de engorde a pradera de novillos sobre las concentraciones de glucógeno muscular y hepático, y sobre las características de calidad de la canal y la carne relacionadas con corte oscuro. Se utilizaron 72 novillos de origen lechero (Overo Negro y Colorado), con peso inicial entre 460 y 520 kg. Dentro de cada tratamiento los 36 novillos con y sin suplementación fueron asignados al azar a uno de cuatro tiempos de duración del experimento (7, 14, 21 y 28 días, 9 novillos cada uno). El modelo estadístico usado fue completamente al azar con arreglo factorial 2x4 (2 tratamientos y 4 duraciones), se incluyó además, la interacción dieta x duración de la suplementación, la edad por cronometría dentaria y como covariable el peso inicial de los novillos. La suplementación en base a maíz roleado permitió mejorar características de la canal como peso, rendimiento centesimal, área del ojo del lomo y cobertura grasa. Aunque las concentraciones promedio de glucógeno muscular no difirieron entre tratamientos, la suplementación con maíz roleado ayudó a prevenir la presencia de corte oscuro, evaluada por color y pH del músculo Longissimus thoracis.