Effect of water activity in tortilla and its relationship on the acrylamide content after frying

The objective of this study was to relate the tortilla minimum integral desorption entropy with acrylamide content during processing of tortilla chips. Tortilla pieces were stored at 30 °C at aw of 0.11-0.84 for 4 days and fried later in soybean oil at 180 °C for 25 s. The lowest acrylamide content was observed in tortilla chips made of non-stored tortilla (aw = 0.98) as well as in those prepared from tortilla stored in the minimum integral entropy (aw = 0.53). In addition, the color and texture values were similar in both cases. These results suggest that the reduction of the acrylamide content during processing of tortilla chips and other tortilla based foods thermally processed might be modified by factors such as moisture content, aw, and the physical state of water in the tortilla. Thus, the minimum integral entropy showed to be a reliable indicator to establish the most appropriate moisture conditions to obtain tortilla chips with reduced level of acrylamide when tortilla is dehydrated. © 2014 Elsevier Ltd. All rights reserved.We are indebted to Juan Veles, Edmundo Gutierrez, Carlos Alberto Ávila, Araceli Mauricio and Veronica Flores from CINVESTAV Querétaro for their technical assistance.Peer Reviewe

Síntesis y caracterización de un material criogénico a partir de quitosano y celulosa

Los criogeles formados a partir de los polisacáridos quitosanoy celulosa están conformados por una red macroporosa e interconectada con áreas superficiales altas. Dichos criogeles ofrecen un uso prometedor en la remoción de cobre a partir de soluciones acuosas. Este trabajo propone la ruta de síntesis del criogel quitosano-etilenglicol diglicidil éter-celulosa (Q-egde-C) y en él se presentan los resultados obtenidos de la caracterización de este material con la finalidad de evaluarlo en trabajos posteriores como adsorbente de iones Cu+2. Las pruebas y técnicas de caracterización utilizadas fueron: solubilidad, porcentaje de hidratación, microscopía electrónica de barrido(MEB), espectroscopía infrarroja por transformada de Fourier(FTIR), área específica y potencial Z. El criogel obtenido es un biomaterial insoluble en agua, con un índice de hinchamiento de ca. 1921 %; su estructura macroporosa contiene grupos amino primarios (–NH2) con un área superficial de 16 m2/g. La síntesis presentada es sencilla con un buen control morfológico en la escala micro y nanométrica, así mismo el criogel mostró mediante la determinación del potencial Z que es capaz de interaccionar con el ión Cu+2 presente en agua

Trends in Tissue Regeneration: Bio-Nanomaterials

Tissue engineering requires functional platforms or scaffolds with specific properties concerning the morphology, chemistry of the surface and interconnectivity to promote cell adhesion and proliferation. These requisites are not only important for cellular migration but also to supply nutrients and expulsion of waste molecules. Cell type must be considered when designing a specific cellular grown system as a scaffold; for instance, if they are autologous, allogeneic or xenogeneic. The challenge in tissue engineering is to develop an organized three-dimensional architecture with functional characteristics that mimic the extracellular matrix. In this regard, with the advent of nanotechnology scaffolds are now being developed that meet most of the aforementioned requisites. In the present chapter, the use of biopolymers based nanostructures is addressed, including biomaterials and stem cells, bio-nanocomposites, and specific clinical cases where these systems were employed. We emphasize the future challenges and perspectives in the design of biocompatible and nontoxic nanocomposites with high efficiency as a promoter for tissue regeneration and many other biomedical applications

Gelatin–chitosan–PVA hydrogels and their application in agriculture

This work demonstrated the ability of a fabrication process in the preparation of gelatin-chitosan-PVA hydrogels for potential agricultural applications. The hydrogels showed a dense, tridimensional, interconnected and reticulated structure that was more evident in the hydrogel loaded with inulin. The hydrogels showed a water absorption capacity of ≤12 times its mass. FTIR and light microscopy demonstrated that the hydrogels were biodegradable. The percentage of degradation of hydrogels in inoculated soil was higher than in sterile soil using the soil burial test. Hydrogel loaded with inulin was found to be capable of inducing resistance in chili plants against Phytophthora capsici.ITESO, A.C

Atomic surface segregation and structural characterization of PdPt bimetallic nanoparticles

"Bimetallic nanoparticles are of interest since they lead to many interesting electrical, chemical, catalytic, and optical properties. They are particularly important in the field of catalysis since they show superior catalytic properties than their monometallic counterparts. The structures of bimetallic nanoparticles depend mainly on the synthesis conditions and the miscibility of the two components. In this work, PdPt alloyed-bimetallic nanoparticles (NPs) were synthesized through the polyol method, and characterized using spherical aberration (Cs) corrected scanning transmission electron microscopy (STEM). High-angle annular dark-field (HAADF)-STEM images of bimetallic nanoparticles were obtained. The contrast of images shows that nanoparticles have an alloy structure with an average size of 8.2 nm. Together with the characterization of nanoparticles, a systematic molecular dynamics simulations study focused on the structural stability and atomic surface segregation trends in 923-atom PdPt alloyed-bimetallic NPs was carried out.

Potential Use of Chitosan-TiO₂ Nanocomposites for the Electroanalytical Detection of Imidacloprid

The detection of toxic insecticides is a major scientific and technological challenge. In this regard, imidacloprid is a neonicotinoid that is a systemic insecticide that can accumulate in agricultural products and affect human health. This work aims to study the properties of chitosan–TiO2 nanocomposites in which nanoparticles with high surface area serve as molecular recognition sites for electroanalytical imidacloprid detection. We show that the best sensitivity to imidacloprid was obtained using a modified electrode with a chitosan–TiO2 nanocomposite with a 40 wt.% of TiO2 nanoparticles. By using a three-phase effective permittivity model which includes chitosan, TiO2, an interface layer between nanoparticles and a matrix, we showed that nanocomposites with 40 wt.% of TiO2 the interface volume fraction reaches a maximum. At higher nanoparticle concentration, the sensitivity of the sensor decreases due to the decreasing of the interface volume fraction, agglomeration of nanoparticles and a decrease in their effective surface area. The methodology presented can be helpful in the design and optimization of polymer-based nanocomposites for a variety of applications

Efecto del tiempo de cocimiento y reposo del grano de maíz (Zea mayz l.) nixtamalizado, sobre las características fisicoquímicas, reológicas, estructurales y texturales del grano, masa y tortillas de maíz

La tortilla es uno de los alimentos más importantes en México y algunos países de Centroamérica. La gran mayoría de las tortillas consumidas en México se elaboran con masa de maíz procesado por el método tradicional de nixtamalización, el cual incluye las etapas de cocimiento y reposo. Durante estas etapas las propiedades fisicoquímicas y estructurales del grano se ven fuertemente afectadas, provocando cambios en las propiedades de la tortilla producida. En este trabajo se evaluaron los cambios en la humedad, viscosidad máxima, almidón dañado y cristalinidad en grano, masa y tortillas; adhesión y pérdida de peso en masas; y rolabilidad, elasticidad y fuerza al corte en tortillas, en función del tiempo de cocimiento y reposo, manteniendo constantes las condiciones de molienda y cocimiento de la tortilla. Se observó que la humedad del grano aumentó hasta 42 g/100g durante el tiempo total de cocimiento (45 min), y alcanzó un máximo (52-53 g/100 g) al someterlo a reposo durante 4 h. Las tortillas de todos los tratamientos mostraron buena rolabilidad. Todos los parámetros evaluados presentaron altos coeficientes de correlación con las propiedades de textura, medidas objetivamente, de las tortillas. El almidón dañado, fue la variable que mejor se correlacionó con el resto de las propiedades evaluadas, presentando altos coeficientes (R>0,92, pEffects of cook and steep time of nixtamalized corn grain (Zea mayz L.) on the physicochemical, rheological, structural and textural characteristics of grain, masa and tortillas. The corn tortilla is elaborated using corn grain masa processed by the traditional nixtamalization method, which consists of two steps: cooking and steeping. In these steps the physicochemical and structural properties are strongly affected, resulting in changes in the textural characteristics of the tortilla produced. In this work the effects of cooking and steeping time on the moisture content, amylographic profiles, crystallinity, weigh loss from masa to tortilla, starch damage, rollability, elasticity and cutting force for grain, masa and corn tortillas, were evaluated. The milling of the nixtamalized grain and the cooking of tortilla conditions were the same in all treatments. All tortillas samples showed a good rollability. The results show that the moisture content of corn grain was increased up to 42 g/100 g during the total cooking time (45 min), and it further increased to 52-53 g/100 g after when the cooked grain was steeped for 4h. All evaluated parameters showed high correlation coefficients with the texture properties of tortillas. The starch damage was the variable with the best correlation among all evaluated parameters. The correlation coefficients between starch damage and moisture content, weigh loss and maximum viscosity for corn grain, masa and tortillas were larger than 0,92 (p<0,01). The best tortillas were produced using nixtamal with the follow characteristics: moisture content of nixtamal, 4244 g/100 g and tortilla, 43-44 g/100 g; adhesiveness of masa, 30-50 g; maximum viscosity of nixtamal, 860-880 cp and tortilla 490-510 cp; starch damage of nixtamal, 14 g/100 g and tortilla, 35-37 g/100 g, and weigh loss of tortilla during cooking, 16 g/100

Deep eutectic solvents as both active fillers and monomers for frontal polymerization

The deep eutectic solvents (DESs) based on the mixtures of a variety of ammonium salts and hydrogen bond donors containing acrylic acids and acrylamides are capable of sustaining frontal polymerization (FP). The selection of ammonium salt affects the reactivity and allows FP at relatively low temperature but with full conversion. Also, full conversion allows us to use these polymers for biomedical applications (e.g., drug delivery systems) as the unreactive ammonium salts can be released from the resulting polymer without by-products. We call these components >active fillers,> which can be ammonium salts with biological or pharmaceutical importance. For instance, we prepared poly(acrylic acid) loaded with lidocaine hydrochloride (a common anesthetic), the release of which was found to occur in a controlled fashion. The ammonium salts also create a sufficiently high viscosity to suppress buoyancy-driven convection without additional materials. The DES here described played an all-in-one role, providing the monomer, the active filler, and the polymerization medium for FPs. © 2013 Wiley Periodicals, Inc.Funded by: CONACYT. Grant Number: 181678.Peer Reviewe