Hydrogels Are Reinforced with Colombian Fique Nanofibers to Improve Techno-Functional Properties for Agricultural Purposes

Colombia es el mayor productor mundial de fibras de fique (Furcraea bedinghausii), con una producción neta de 30.000 toneladas anuales. Este trabajo propone revalorizar los residuos de la agroindustria colombiana del fique. Para ello, se obtuvieron nanofibras de celulosa del fique y se utilizaron como material de refuerzo para crear hidrogeles acrílicos superabsorbentes. Se sintetizaron hidrogeles acrílicos no reforzados (AHR0) e hidrogeles acrílicos reforzados con nanofibras de fique al 3 % p/p (AHR3), 5 % p/p (AHR5) y 10 % p/p (AHR10) utilizando el método de polimerización en solución. La mejor formulación de hidrogel para fines agrícolas se eligió comparando su comportamiento de hinchamiento, propiedades mecánicas y usando microscopía electrónica de barrido (SEM). Al elevar la concentración de nanofibras al 3% (AHR3), la formulación mejor elegida, aumentó la interacción entre las nanofibras y la matriz polimérica, lo que favoreció la estabilidad de la red. Sin embargo, más allá de AHR3, hubo una mayor viscosidad del sistema reactivo, lo que provocó una reducción en la movilidad de las cadenas poliméricas, desfavoreciendo así la capacidad de hinchamiento. El hidrogel reforzado propuesto en este estudio (AHR3) podría representar un aporte para superar los problemas de aridez de la tierra que se presentan en Colombia, tema que se agudizará en los próximos años debido a la emergencia climática.Colombia is the world’s largest producer of fique fibers (Furcraea bedinghausii), with a net production of 30,000 tons per year. This work proposes to revalue waste from the Colombian fique agroindustry. For this purpose, cellulose nanofibers were obtained from fique and used as reinforcement material to create acrylic superabsorbent hydrogels. Unreinforced acrylic hydrogels (AHR0) and acrylic hydrogels reinforced with fique nanofibers at 3% w/w (AHR3), 5% w/w (AHR5), and 10 % w/w (AHR10) were synthesized using the solution polymerization method. The best hydrogel formulation for agricultural purposes was chosen by comparing their swelling behavior, mechanical properties, and using scanning electron microscopy (SEM). By raising the nanofiber concentration to 3% (AHR3), the best-chosen formulation, the interaction between the nanofibers and the polymer matrix increased, which favored the network stability. However, beyond AHR3, there was a higher viscosity of the reactive system, which caused a reduction in the mobility of the polymer chains, thus disfavoring the swelling capacity. The reinforced hydrogel proposed in this study (AHR3) could represent a contribution to overcoming the problems of land dryness present in Colombia, an issue that will worsen in the coming years due to the climate emergency.na10 página

Dried fruit breadfruit slices by Refractive Window™ technique

Una gran cantidad de productos son secados por diversas razones, tales como la preservación, la reducción de peso y el mejoramiento de su estabilidad. Sin embargo, los métodos tradicionales de secado de alimentos sólidos no presentan productos de bajo costo y alta calidad de manera simultánea. A pesar de que existen métodos efectivos de deshidratación de los alimentos como la liofilización, que preserva el sabor, color y las vitaminas, son tecnologías de poca accesibilidad, por lo cual se hacen necesarios procesos alternativos que sean eficientes y económicos. El objetivo de esta investigación fue comparar la cinética del secado de rebanadas de fruto del árbol del pan (Artocarpus communis) mediante la técnica de Ventana Refractiva® (VR) con la de secado en bandeja. Para llegar a cabo este trabajo, se usaron rodajas de 1 y 2 mm de espesor. El secado con VR se realizó con temperatura del baño de agua a 92 °C; y el secado en bandeja a 62 °C y una velocidad del aire de 0,52 m/s. Durante el secado por la técnica de VR, el contenido de humedad llega a niveles más bajos que el secado en bandejas. De igual manera sucede con las muestras de 1 mm, las cuales, por tener menor diámetro alcanzan niveles de humedad inferior que las muestras de 2 mm. Las mayores difusividades se obtuvieron durante el secado por VR en rodajas de 1 y 2 mm con coeficientes de 6,13 y 3,90*10-9 m2/s respectivamente.A large amount of products are dried due several reasons as preservation, weight reduction and improvement of stability. However, on the market are not offered low-cost and high quality products simultaneously. Although there are effective methods of dehydrating foods such as freeze drying, which preserves the flavor, color and vitamins, they are poor accessibility technologies. Therefore, alternative processes are required to be efficient and economical. The aim of this research was compare drying kinetics of sliced of breadfruit (Artocarpus communis) using the technique of Refractive Window® (VR) with the tray drying. To carry out this study, sliced of 1 and 2 mm thick were used. Refractive window drying was performed with the water bath temperature to 92 °C; and tray drying at 62 °C and an air velocity of 0.52 m/s. During the Refractive window drying technique, the moisture content reached the lower than tray drying levels. Similarly it happened with samples of 1 mm, which, having a smaller diameter reached lower moisture levels than samples 2 mm. The higher diffusivities were obtained during drying sliced VR 1 and 2 mm with coefficients of 6.13 and 3.90*10-9 m2/s respectively

Evaluation of the lactate of sodium as a substitute for conventional nitrites in fish sausages

La sal sódica del ácido láctico es un ácido natural producido por las bacterias en los alimentos fermentados, los cuales son ricos en este componente. Es producido mediante la fermentación de azúcares procedentes de algunos productos como el maíz o la remolacha. Tanto el ácido láctico como los lactatos son usados como conservantes, principalmente contra las levaduras y los hongos. Es usado también para incrementar la estabilidad de los antioxidantes, y para prevenir la pérdida de agua de diversos productos. El objetivo de la presente investigación fue determinar la efectividad del lactato de sodio sobre la inhibición del Clostridium sporogenes en salchichas de pescado, extendiendo su vida útil y reduciendo el crecimiento microbiano. Se realizaron dos formulaciones diferentes; F(A) conservadas con nitritos, F(B) conservadas con lactato de sodio y una muestra control sin conservantes. También se realizó un control positivo con agar SPS inoculándose el Clostridium sporogenes en las diferentes diluciones, por último se llevaron a incubación en la jarra de anaerobiosis a 37°C por 48 h. Se pudo comprobar que la utilización de lactato de sodio al 2% controló el crecimiento de esporas de Clostridium sulfito reductor a las 48 h en las disoluciones preparadas al igual que la utilización de nitritos, siendo estos una alternativa prometedora para reemplazar el uso de nitritos en productos cárnicos tipo salchicha.The sodium salt of lactic acid is a natural acid produced by bacteria in the fermented foods which are rich in this component. It is produced by fermentation of sugars from some products such as corn or beets. Both lactic acid and lactates are used as preservatives, mainly against yeasts and fungi. It is also used to increase the stability of antioxidants, and to prevent loss of water from various products. The objective of this research was to determine the effectiveness of sodium lactate on the inhibition of Clostridium sporogenes in fish sausages, extending their life and reducing microbial growth. Two different formulations were made; F(A) preserved with nitrites, F(B), preserved with sodium lactate and a control sample without preservative. A positive control SPS agar inoculated with Clostridium sporogenes at different dilutions were also carried out, finally they took incubation in candle jar at 37°C for 48 h. It was found that the use of sodium lactate 2% controlled growth of spores of Clostridium reducing sulfite in 48 hours in the solutions prepared as is the use of nitrites, these being a promising alternative to replace the use of nitrite in products type sausage meat

Geographic patterns of tree dispersal modes in Amazonia and their ecological correlates

Aim: To investigate the geographic patterns and ecological correlates in the geographic distribution of the most common tree dispersal modes in Amazonia (endozoochory, synzoochory, anemochory and hydrochory). We examined if the proportional abundance of these dispersal modes could be explained by the availability of dispersal agents (disperser-availability hypothesis) and/or the availability of resources for constructing zoochorous fruits (resource-availability hypothesis). Time period: Tree-inventory plots established between 1934 and 2019. Major taxa studied: Trees with a diameter at breast height (DBH) ≥ 9.55 cm. Location: Amazonia, here defined as the lowland rain forests of the Amazon River basin and the Guiana Shield. Methods: We assigned dispersal modes to a total of 5433 species and morphospecies within 1877 tree-inventory plots across terra-firme, seasonally flooded, and permanently flooded forests. We investigated geographic patterns in the proportional abundance of dispersal modes. We performed an abundance-weighted mean pairwise distance (MPD) test and fit generalized linear models (GLMs) to explain the geographic distribution of dispersal modes. Results: Anemochory was significantly, positively associated with mean annual wind speed, and hydrochory was significantly higher in flooded forests. Dispersal modes did not consistently show significant associations with the availability of resources for constructing zoochorous fruits. A lower dissimilarity in dispersal modes, resulting from a higher dominance of endozoochory, occurred in terra-firme forests (excluding podzols) compared to flooded forests. Main conclusions: The disperser-availability hypothesis was well supported for abiotic dispersal modes (anemochory and hydrochory). The availability of resources for constructing zoochorous fruits seems an unlikely explanation for the distribution of dispersal modes in Amazonia. The association between frugivores and the proportional abundance of zoochory requires further research, as tree recruitment not only depends on dispersal vectors but also on conditions that favour or limit seedling recruitment across forest types

Mapping density, diversity and species-richness of the Amazon tree flora

Using 2.046 botanically-inventoried tree plots across the largest tropical forest on Earth, we mapped tree species-diversity and tree species-richness at 0.1-degree resolution, and investigated drivers for diversity and richness. Using only location, stratified by forest type, as predictor, our spatial model, to the best of our knowledge, provides the most accurate map of tree diversity in Amazonia to date, explaining approximately 70% of the tree diversity and species-richness. Large soil-forest combinations determine a significant percentage of the variation in tree species-richness and tree alpha-diversity in Amazonian forest-plots. We suggest that the size and fragmentation of these systems drive their large-scale diversity patterns and hence local diversity. A model not using location but cumulative water deficit, tree density, and temperature seasonality explains 47% of the tree species-richness in the terra-firme forest in Amazonia. Over large areas across Amazonia, residuals of this relationship are small and poorly spatially structured, suggesting that much of the residual variation may be local. The Guyana Shield area has consistently negative residuals, showing that this area has lower tree species-richness than expected by our models. We provide extensive plot meta-data, including tree density, tree alpha-diversity and tree species-richness results and gridded maps at 0.1-degree resolution

Consistent patterns of common species across tropical tree communities

Trees structure the Earth’s most biodiverse ecosystem, tropical forests. The vast number of tree species presents a formidable challenge to understanding these forests, including their response to environmental change, as very little is known about most tropical tree species. A focus on the common species may circumvent this challenge. Here we investigate abundance patterns of common tree species using inventory data on 1,003,805 trees with trunk diameters of at least 10 cm across 1,568 locations1,2,3,4,5,6 in closed-canopy, structurally intact old-growth tropical forests in Africa, Amazonia and Southeast Asia. We estimate that 2.2%, 2.2% and 2.3% of species comprise 50% of the tropical trees in these regions, respectively. Extrapolating across all closed-canopy tropical forests, we estimate that just 1,053 species comprise half of Earth’s 800 billion tropical trees with trunk diameters of at least 10 cm. Despite differing biogeographic, climatic and anthropogenic histories7, we find notably consistent patterns of common species and species abundance distributions across the continents. This suggests that fundamental mechanisms of tree community assembly may apply to all tropical forests. Resampling analyses show that the most common species are likely to belong to a manageable list of known species, enabling targeted efforts to understand their ecology. Although they do not detract from the importance of rare species, our results open new opportunities to understand the world’s most diverse forests, including modelling their response to environmental change, by focusing on the common species that constitute the majority of their trees.Publisher PDFPeer reviewe

Unraveling Amazon tree community assembly using Maximum Information Entropy: a quantitative analysis of tropical forest ecology

In a time of rapid global change, the question of what determines patterns in species abundance distribution remains a priority for understanding the complex dynamics of ecosystems. The constrained maximization of information entropy provides a framework for the understanding of such complex systems dynamics by a quantitative analysis of important constraints via predictions using least biased probability distributions. We apply it to over two thousand hectares of Amazonian tree inventories across seven forest types and thirteen functional traits, representing major global axes of plant strategies. Results show that constraints formed by regional relative abundances of genera explain eight times more of local relative abundances than constraints based on directional selection for specific functional traits, although the latter does show clear signals of environmental dependency. These results provide a quantitative insight by inference from large-scale data using cross-disciplinary methods, furthering our understanding of ecological dynamics

Unraveling Amazon tree community assembly using Maximum Information Entropy: a quantitative analysis of tropical forest ecology

In a time of rapid global change, the question of what determines patterns in species abundance distribution remains a priority for understanding the complex dynamics of ecosystems. The constrained maximization of information entropy provides a framework for the understanding of such complex systems dynamics by a quantitative analysis of important constraints via predictions using least biased probability distributions. We apply it to over two thousand hectares of Amazonian tree inventories across seven forest types and thirteen functional traits, representing major global axes of plant strategies. Results show that constraints formed by regional relative abundances of genera explain eight times more of local relative abundances than constraints based on directional selection for specific functional traits, although the latter does show clear signals of environmental dependency. These results provide a quantitative insight by inference from large-scale data using cross-disciplinary methods, furthering our understanding of ecological dynamics

Mapping density, diversity and species-richness of the Amazon tree flora

Using 2.046 botanically-inventoried tree plots across the largest tropical forest on Earth, we mapped tree species-diversity and tree species-richness at 0.1-degree resolution, and investigated drivers for diversity and richness. Using only location, stratified by forest type, as predictor, our spatial model, to the best of our knowledge, provides the most accurate map of tree diversity in Amazonia to date, explaining approximately 70% of the tree diversity and species-richness. Large soil-forest combinations determine a significant percentage of the variation in tree species-richness and tree alpha-diversity in Amazonian forest-plots. We suggest that the size and fragmentation of these systems drive their large-scale diversity patterns and hence local diversity. A model not using location but cumulative water deficit, tree density, and temperature seasonality explains 47% of the tree species-richness in the terra-firme forest in Amazonia. Over large areas across Amazonia, residuals of this relationship are small and poorly spatially structured, suggesting that much of the residual variation may be local. The Guyana Shield area has consistently negative residuals, showing that this area has lower tree species-richness than expected by our models. We provide extensive plot meta-data, including tree density, tree alpha-diversity and tree species-richness results and gridded maps at 0.1-degree resolution