Se estudió la composición química y la digestibilidad del almidón de cuatro variedades de frijol común (Phaseolus vulgaris L.). No se encontraron diferencias estadísticas (p£0,05) en el contenido de ...proteína y el contenido de lípidos fue bajo pero sin diferencias apreciables. Estos frijoles son buena fuente de minerales (3,67-5,15% cenizas). El valor de almidón total (AT) menor fue para la variedad Flor de Mayo (34,70%) y el mayor para Peruano (42,81%) y Mayocoba (40,24%). Los valores mayores de almidón disponible (AD) se determinaron en las variedades Flor de Mayo (32,27%) y Peruano (31,60%), y los menores en las variedades Mayocoba (22,87%) y Negro (21,7%). La variedad Flor de Mayo presentó el menor valor (2,43%) de almidón resistente (AR), y las variedades con el mayor valor de AT (40,24-42,81%) también tuvieron el valor más alto de AR (5,41-6,4%). Las variedades Flor de Mayo y Peruano mostraron los mayores porcentajes (p£0,05) de hidrólisis (34-37%), lo que coincidió con sus valores de AD. La predicción del índice glucémico (pIG) fue mayor en la variedad Peruano (68,69), y menor en Mayocoba (57,88) y Negro (58,40). Estos valores de pIG se consideran bajos.
Starch-based foams (SBFs) were prepared with corn, potato, tapioca, and chayotextle starches. A compression baking process was used to develop the SBFs. Biodegradation studies showed that different ...sources of starch have a particular behavior. The starches showed values of degradation of ~85%, while the degradation of SBFs was ~70%. The SBFs were conditioned at relative humidities (RHs) of 0 and 75% and temperatures of 4 and 65°C. The starch source used to prepare the SBFs did not have an effect on the mechanical properties, but the storage conditions showed a significant effect on those properties; an increase of RH causes an increase in the mechanical properties. A similar behavior was observed in the conditioned SBFs at different temperatures. The increase of the storage temperature showed a slight reduction in the values of elongation at break. Microscopy revealed that the conditions of RH and storage temperature affect the internal structure of the SBFs.
Antimicrobial films were formulated with sodium caseinate (C), glycerol and antimicrobial substances (AM) produced by Streptococcus infantarius. The antilisterial activity of the films was evaluated ...using Listeria monocytogenes as test microorganism and two incubation conditions: T = 35°C, 32 ± 10% RH and T = 4°C, 98 ± 10% RH. A comparison of the antimicrobial action was made with caseinate films carrying equivalent activity units of commercial nisin (Nis). At 35°C and 32% RH, AM increased the lag-phase and inhibited 80% of the growth of L. monocytogenes. At 4°C and 98% RH, C-Nis and C-AM films extended the lag-phase of the bacterial growth up to 11 and 38 days, respectively. AM showed a higher antilisterial effect than nisin at both incubation conditions. The incorporation of AM or Nis did not produce significant differences in the barrier properties of the films, but AM acted as an additional plasticizer into the films.
Five common bean varieties were cooked and studied regarding starch digestibility. Cooking time of different cultivars ranged between 2.55 and 5.92
h. Available starch (AS) values decreased with the ...storage time and the bean sample that had the lowest AS content (control sample, without storage) showed the shortest cooking time. A similar pattern was found for resistant starch (RS); the varieties that had the longest cooking time presented the widest range in RS values, measured as the difference between the control sample and the value obtained in the sample stored during 96
h. The retrograded RS (RRS) depended on the variety and even more on the molecular structure of each starch. The in vitro
α-amylolysis rate decreased with the storage time; the samples with the smallest hydrolysis percentage had the highest RS content. These results suggest that some bean varieties could be recommended depending on the specific dietetic use of beans.
Films made from a mixture of Chayotextle starch-Gelatin (SG) were prepared in concentrations of SG13, SG22 and SG31 respectively. Two controls were considered; gelatin (G) and starch films (S). ...Glycerol was added as a plasticizer to all treatments at 2%. G treatment presented higher elasticity, permeability and solubility in comparison to those treatments using starch. FT-IR showed that both ingredients gelatin and starch respected their molecular spaces. However, their contribution was relevant for the formation of the matrix of films. The lowest percentage of crystallinity appeared in S films with 30.8%. This value increased up to 48.5 % in the G treatment. The variation of ratios in the mixture gelatin-starch resulted in different degrees of structural composition and these changes could be configured, adapted and applied to the requirements of the food engineering, pharmaceutical, and biomedical industry.
Dentro de las materias primas para elaborar plásticos biodegradables, el almidón tiene un alto potencial; sin embargo, éste debe ser modificado para mejorar sus propiedades de formación de película. ...En el presente estudio almidón aislado de plátano macho (Musa paradisiaca L.) en estado fisiológico inmaduro fue modificado químicamente mediante una oxidación con NaOCl con tres concentraciones de cloro activo (0.5, 1.0 y 1.5 % v/v) y se acetiló usando anhídrido acético. Los almidones se caracterizaron química, física y térmicamente: cuantificación de grupos carbonilos, carboxilos y acetilos; análisis químico proximal; análisis de espectroscopia de infrarrojo con transformada de Fourier; determinación de color; y análisis de variables térmicas mediante calorimetría diferencial de barrido. Los valores cuantificados de grupos funcionales carbonilos, carboxilos y acetilos corroboraron la efectividad de los tratamientos químicos, lo cual se verificó mediante el análisis de espectroscopia de infrarrojo con transformada de Fourier. La modificación por oxidación redujo el contenido de proteínas, lípidos y cenizas. El parámetro L* caracterizó el color de los almidones ya que fue una medida directa de su blancura. Este valor incrementó a medida que aumentó el nivel de oxidación, sin que la modificación por acetilación influyera significativamente en este parámetro. Los parámetros térmicos de temperatura de inicio, pico y final de gelatinización aumentaron cuando se incrementó la concentración de cloro activo, mientras que la entalpía de gelatinización disminuyó indicando una alteración estructural en los almidones modificados, lo cual se confirmó con el perfil amilográfico de estos almidones. Con la doble modificación química fue posible mejorar las propiedades físicas y químicas del almidón nativo de plátano.
Submerged Monoxenic Culture of the Entomopathogenic Nematode, Steinernema carpocapsae CABA01, in a Mechanically Agitated Bioreactor: Evolution of the Hydrodynamic and Mass Transfer Conditions Chavarria-Hernandez, Norberto, Instituto de Ciencias Agropecuarias de la Universidad Autonoma del Estado de Hidalgo Av. Universidad km 1, Rancho Universitario, Tulancingo de Bravo, Mexico; Ortega-Morales, Eduardo, Instituto de Ciencias Agropecuarias de la Universidad Autonoma del Estado de Hidalgo Av. Universidad km 1, Rancho Universitario, Tulancingo de Bravo, Mexico; Vargas-Torres, Apolonio, Instituto de Ciencias Agropecuarias de la Universidad Autonoma del Estado de Hidalgo Av. Universidad km 1, Rancho Universitario, Tulancingo de Bravo, Mexico ...
Biotechnology and bioprocess engineering,
08/2010, Letnik:
15, Številka:
4
Journal Article
Recenzirano
This study is the first to describe the evolution of both hydrodynamic and oxygen transfer conditions during the submerged culture of the entomopathogenic nematode Steinernema carpocapsae CABA01 (an ...indigenous strain isolated within the State of Hidalgo, Mexico), and its symbiotic bacterium, Xenorhabdus nematophila, using an internal-loop mechanically agitated bioreactor of 4.5 L of liquid volume. Concentrations up to 217,306 viable nematodes per mL, with 94% in infective juvenile (IJ) stage (i.e., 204,444 IJ/mL), were achieved in 16 days of bioprocess. The Reynolds number (Re) was used as an index of the actual hydrodynamic conditions, and it varied within the interval 5,150 less than Re (dimensionless) less than 9,440, involving apparent culture broth viscosity changes from 3 to 5.4 mPa s during the processing. The aeration efficiency was expressed on the basis of the volumetric oxygen transfer coefficient, k∧La, which varied within the range 0.026 to 0.170 s-¹.
Nopalea cochenillifera (L.) Salm-Dyck is a scarcely studied cactus; its characterization contributes to identifying the bioactive compounds it contains and its functional properties, which will allow ...generating information on potential uses and applications. The aim of this work was to characterize N. cochenillifera cladodes flour physicochemically and identify the phenolic compounds that it contains. In general, N. cochenillifera flour is low in calories (337%) with high total dietary fiber content (18.41%). In addition, it exhibits good water (11.04%) and oil (2.05%) absorption capacity, while swelling capacity was 25 mL/g DW. The content of soluble and hydrolyzable polyphenols were 207.92 and 647.99 mg EAG/100 g DW, respectively. In addition, they showed antioxidant activity by DPPH• (15.28 mmol TE/g DW), FRAP (20.97 mmol TE/g DW), and ABTS•+ (51.31 mmol TE/g DW) methods. Furthermore, six phenolic acids (gallic, ferulic, chlorogenic, p-coumaric, syringic, and neochlorogenic) were identified by HPLC. According to the results, N. cochenillifera cladodes flour is an important source of fiber and bioactive compounds with interesting functional properties. In this context, N. cochenillifera flour could be used as an ingredient in the formulation of functional foods. However, further, studies are needed on the shelf life and optimizing its preservation process, transformation, and functional potential.
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