Showing papers by "Elevina Pérez published in 2011"

Physicochemical, functional, and macromolecular properties of waxy yam starches discovered from "Mapuey" (Dioscorea trifida) genotypes in the Venezuelan Amazon.

Abstract: "Mapuey" tubers in Venezuela are staple food for indigenous peoples from the Caribbean coast and Amazon regions. Noticeable differences between genotypes of yam starches were observed. Granules were large, triangular, or shell-shaped with monomodal particle size distribution between 24.5 and 35.5 μm. Differential scanning calorimetry (DSC) analyses revealed onset gelatinization temperatures from 69.1 to 73.4 °C with high gelatinization enthalpy changes from 22.4 to 25.3 J g(-1). All X-ray diffractograms of starches exhibit B-type crystallinity. Crystallinity degrees varied from 24% to 40%. The highest crystallinity was found for the genotype having the highest amylose content. Iodo-colorimetric, amperometric, and DSC amylose determinations varied from 1.4 to 8.7%, 2.2 to 5.9%, and 1.4 to 3.5% for Amazonian genotypes, in comparison with commercial Mapuey starches: 12.0, 9.5, and 8.7%, respectively. Solubility and swelling power at 90 °C varied from 2.1 to 4.4% and 20.5 to 37.0%, respectively. Gel clarity fluctuated from 22.4 to 79.2%, and high rapid visco analyzer (RVA) viscosity was developed at 5% starch suspension (between 1430 and 2250 cP). Amylopectin weight average molar mass M(w), radius of gyration R(G), hydrodynamic coefficient ν(G), and apparent molecular density d(Gapp) were determined using high-performance size exclusion chromatography (HPSEC) and asymmetrical flow field flow fractionation (A4F) techniques coupled with multiangle laser light scattering (MALLS) on the Dioscorea trifida genotypes exhibiting the lowest and highest amylose contents. Amylopectins showed very similar molecular conformations. M(w) values were 1.15 × 10(8) and 9.06 × 10(7) g mol(-1) using HPSEC and A4F, respectively, thus, 3-5 times lower than those reported with the same techniques for other yam species, and very close to those of potato and cassava amylopectins. This discovery of a new natural amylose-free starch in the neglected yam "Mapuey" could present some potential for the food industry.

Characterization of the proteins fractions extracted from leaves of Amaranthus dubius (Amaranthus spp.)

Abstract: Amaranth is an ancient plant belonging to the Amaranthaceae family, which is believed to have originated in Central and South America. The high nutritional quality of the amaranth seed protein is one of the main factors that has attracted the attention of the researchers. However, till date, the protein profile of the leaves of the most researched varieties has not been well studied. Moreover, the nutritional profile of Amaranthus dubius remains unknown. Therefore, it would be interesting to study it. Protein from A. dubius leaves has a high nutritional value due to its balanced amino acid composition. The concentrations of albumins, globulins, prolamins and glutelins are 73.42, 6.60, 6.47 and 6.11%, respectively. It was found that the best agent for extraction of globulins was Na2HPO4 and for glutelins, it was NaOH. The highest amino acid content was found in the albumins fraction and the lowest one in the glutelins fraction. The chemical score of the essential amino acids from proteins of the leaves of A. dubius flour was 92.83%; the flour has only one limiting essential amino acid: Leucine (Leu). The leaves of A. dubius can be used as complement dietary for rice, wheat and corn proteins. Key words: Amaranth, amino acids, protein content, protein fractions.

Evaluation of the Functional Properties of Promising Dioscorea trifida L. Waxy Starches for Food Innovation

Abstract: Few natural waxy starches are offered to the industry demand. Therefore, the morphological, physical, and chemical characteristics of “Mapuey” waxy starch were assessed. Amylose contents of starches isolated from Dioscorea trifida L. (“Mapuey”) landraces cultivated in the Amazons of Venezuela were lower ( 8.7%). DSC onset gelatinization temperatures varied from 71.1 to 73.2°C. All starches exhibited B-type patterns, with degrees of crystallinity varying from 28% to 33%. The highest crystallinity was found for the starches exhibiting the highest amylose content. At 90°C, solubility and swelling power varied from 2.3 to 4.3% and 20.9 to 32.8%, respectively. Gel clarity was variable from 20.8 to 62.1%. A 5% starch suspension induced a high RVA peak viscosity between 1667 and 2037 cP. This natural waxy yam resource is a promising ingredient for food industry.

Evaluation of some properties of starch and starch edible films from sub-utilized roots and tubers from the Venezuelan Amazons

Abstract: Biopolymers extracted from agricultural starchy commodities can be raw materials for edible, biologically degradable plastics. They have promising uses, having been proposed for replacing synthetic films. There are several starchy sources not yet quite exploited such as tropical roots and tubers that could be excellent starch sources to produce edible films with distinctive functional properties. The objective of this study was to formulate edible films ITom six tropical root and tubers starches. Starches were extracted and purified to 97-99% purity ITom Ipomoea batatas, andArracacia xanthorriza roots, Colocasia esculenla and Xanthosoma sagi/lifolium corms and Dioscorea Irifida tubers (white and purple) cultivated in the Venezuelan Amazons. The non-conventional stilrches were characterized for purity, amylose content and gelatinization profile by OSC, starch granular morphometry, and rheological properties. Film forming suspensions were formulated to produce the edible films using starch (2.5 ahd 5.00 g /100 g of solution) and glycerol (1.50 and 2.5 g/100 g of solution). Starch suspensions were gelatinized by heat, degassed, poured in plates and dried. In the films, the following studies were performed: Mechanical properties, thickness, and water vapor, oxygen and COl permeability. Films were very good barriers to gases, had high water permeability and the botanical origin may affect the properties of the films. Nonconventional sources can be used for film preparation with barrier and mechanical characteristics that can be tailored for specific uses in the food industry. Next studies to conduct on films are Scanning Electron MicroscQPY, X-ray diffraction, and other supramolecular tests. (Resume d'auteur)

Elaboration of blackberry (Rubus glaucus Benth.) jellies with native and modified banana starches (Musa ABB)

Abstract: To diversify the use of tropical fruits such as “topocho” (Musa ABB) and blackberry (Rubus glaucus Benth.), jellies were formulated, and thickened with 20% of native starch (BS), and modified granular starch (GBS) starch from unripe “topocho” with, and without the addition of carboxymethylcellulose (CMC) using corn starch as control. A sensorial evaluation of the recipes was completed (without CMC at cero time) to determine the preferred jelly. The physical and chemical properties of the stored jellies at refrigeration temperature (4oC) during 10 days were also evaluated. The data shown that the jellies elaborated with native starch and corn starch did not show statistical significant differences (p£0.05) in all of the parameters studied. When comparing the jellies elaborated with topocho starch to those elaborated with corn starch during the first five days of storage, the data did not reveal any significant variation in the oBrix, (33.5 a 38.5), pH (3.4 a 3.9), titratable acidity (237.8 a 236 mg, as citric acid/100 ml of the sample), apparent viscosity (75 a 65 Pas) and syneresis. In addition to diversify the use of the blackberries, topocho starch could be a good substitute for the commercial corn starch to produce jellies. Key words: Musaceas, native starch, modified starch blackberries, jellies.

Proximal composition and categorization by the amylose content of rice (Oryza sativa L.) varieties

Abstract: Composicion proximal y categorizacion de variedades de arroz (Oryza sativa L.) por su contenido de amilosa A pesar de su gran importancia, el arroz (Oryza sativa L.) se clasifica con base en sus parametros industriales y comerciales y no por su valor nutricional. Basado en estos postulados, los objetivos de esta investigacion fueron evaluar la composicion proximal de 23 variedades de arroz pulido obtenidas de cosechas experimentales ('Vivero italiano1', 'F2000Mejorado', 'PN00A007', 'Vivero italiano', 'Vivero italiano2', 'PN00A017B', 'F2000', 'PN99A003', 'PN01A013' y 'PN00A014') y comerciales ('Fedearroz 50', 'Z-15', 'FONAIAP-1', 'D-Sativa' y 'Cimarron') del Instituto Nacional de Investigaciones Agricolas y de la Republica de China ('Tianjin', 'Local indico', 'Japonesa NE', 'Waxy vitreos', 'Japonesa X' y 'Japonesa'), asi como marcas comerciales del mercado local venezolano ('A1' y 'A2'). Las variedades y cultivares fueron caracterizadas en su composicion proximal y el contenido de amilosa aparente fue determinado por metodo colorimetrico. Los resultados senalaron diferencias significativas entre las variedades (p 10-25%). Palabras clave: Oryza sativa L, arroz pulido, variedades comerciales, composicion proximal, amilosa, calidad del grano. In spite of its great importance, rice (Oryza sativa L.) is classified on the base of its industrial and commercial parameters, and not on its nutritional value. Based on this fact, the goals of this research were to evaluate the proximal composition of 23 varieties of polished rice retrieved from experimental crops ('Vivero italiano1', 'F2000Mejorado', 'PN00A007', 'Vivero italiano', 'Vivero italiano2', 'PN00A017B', 'F2000', 'PN99A003', 'PN01A013', and 'PN00A014') and commercial ('Fedearroz 50', 'Z-15', 'FONAIAP-1', 'D-Sativa', and 'Cimarron') grown by the Instituto Nacional de Investigaciones Agricolas, and from the Republic of China ('Tianjin', 'Local indico', 'Japanese NE', 'Waxy vitreos', 'Japanese X' and 'Japanese'), as well as from the Venezuelan local market ('A1' and 'A2'). The varieties and cultivars were characterized in its proximal composition by official methods, and apparent amylose content was determined by a colorimetric method. Results pointed out highly significant differences among the varieties (p 10-25%). Key words: Oryza sativa L, polished rice, commercial varieties, proximal composition, amylose, grain quality.

Evaluación y comparación

Abstract: Evaluation and comparison of the alimentary behavior of health proffesionals in two hospital centers

Efecto del calentamiento sobre la ultra estructura del almidón de batata (Ipomoea batatas L.)

Abstract: En este estudio se caracterizo la morfometria del almidon de batata (Ipomoea batatas L.) empleando los microscopios optico y electronico (SEM). Tambien, se evaluo el efecto del calentamiento sobre la estructura de los almidones mediante el uso de tecnicas con SEM. Los resultados indican que la poblacion granular vario en una amplio rango de tamanos (4,84-25,81 μm) con un valor promedio de 12,53 μm. Los granulos presentaron formas que variaron de redondas y poliedricas pequenas, a grandes en forma de campana. Los granulos mostraron una textura lisa con algunas excoriaciones en la superficie. Las transformaciones principales ocurridas durante el calentamiento se podrian resumir como sigue: primero, hinchamiento granular, seguido por la fusion de la mayor parte de los granulos debido a la solubilidad y a la lixiviacion completa de la amilosa; segundo, la gelatinizacion completa de los granulos y tercero, la transformacion de la organizacion granular en una estructura reticular planar. En esta estructura reticular esta embebido el resto de los granulos hinchados libres de amilosa, que no han perdido su estructura externa. Se observaron estructuras o micro fibrillas que fueron consideradas como moleculas de amilosa, las cuales pudieron ser lixiviadas a traves de los microporos de la superficie granular. Por otra parte, se observo la presencia de los granulos llamados "fantasma". El conocimiento de las caracteristicas y la estructura del almidon de batata facilitarian grandemente su uso. Palabras clave: Ipomoea batatas, microscopia, calentamiento, estructura granular. Effect of heating on the ultra structure of sweet potato (Ipomoea batatas L.) starch ABSTRACT The size and morphology of sweet potato (Ipomoea. batatas L.) starch were characterized by using the optic and scanning electronic microscopes (SEM). Also, the effect of heating on the same structure was evaluated with SEM. The results indicated that the granular population varied with an ample diameter range (4.84-25.81μm) and with an average value of 12.53 μm. The granules had small round, polyhedrical and large bell-like forms. The granules showed a smooth texture with some excoriations in their surface. The main transformations involved during the heating could be summarized as follow: first, the maximum granular swelling was reached, followed by the fusion of most of the granules due to the solubilization and complete leaching of the amylose; second, the complete gelatinization of granules, and third, the transformation of the granular organization into planar reticular structure. In this structure, the rest of the amylose-free swollen granules that did not lose the external structure was imbibed. Structures or microfibrills that were considered asamylose molecules were observed. This amylose could be leached out the microspores. Moreover, the presence of "ghost" granules was observed. The knowledge of the properties and the structure of the sweet potato starch would greatly increase its use. Key words: Ipomoea batatas, microscopy, heating, granular structure