Diferencias estructurales y reológicas entre almidones de frutas y cereales
2012
espanolLos almidones se usan con varios fines en la industria segun sus propiedades funcionales, las cuales son influenciadas por su organizacion estructural. El objetivo de este estudio fue evaluar las caracteristicas morfologicas, fisicoquimicas y reologicas de almidones de cereales (maiz y cebada; Zea mays L. y Hordeum vulgare L.) y frutas (platano y mango; Musa paradisiaca y Mangifera indica). Los granulos del almidon de maiz eran esfericos, ovales y poligonales, entre 5 y 20 μm; los de cebada eran esfericos, entre 2 y 5 μm y ovales entre 15 y 25 μm; los de mango eran esfericos o de domo y punta, entre 5 y 12 μm; los de platano eran alargados, con longitud promedio de 40 a 45 μm. El patron de difraccion de rayos X de los almidones de los cereales fue tipo A- y el de los frutos tipo C-. Estos alcanzaron perfiles de formacion de pasta mayores e indices de consistencia mayores que los de cereales; todos mostraron un comportamiento no-Newtoniano. En sus geles, el nivel de reorganizacion de los almidones no dependio de su fuente, sino de su estructura. La temperatura de pico y entalpia de gelatinizacion se relacionaron directamente con el tamano de los granulos. Sin embargo, su porcentaje de retrogradacion fue independiente del tamano de granulo y del patron de difraccion de rayos X. Por tanto, la organizacion de los cristales dependio de la conformacion de las dobles helices de la amilopectina. Se concluye que el uso de los almidones depende de su organizacion estructural que le confiere caracteristicas independientes de la fuente. EnglishStarches are used for several purposes in industry depending on their functional properties, which are affected by their structural organization. The objective of this study was to evaluate the morphological, physicochemical and rheological characteristics of cereals (maize, Zea mays L., and barley, Hordeum volgare L.) and fruits (banana, Musa paradisiacal, and mango, Mangifera indica) starches. Maize starch granules were spherical, elliptical and polygonal, between 5 and 20 μm; those of barley were spherical between 2 and 5 μm and oval, between 15 and 25μm; those of mango starch were spherical or dome-shaped and split, with sizes between 5 and 12μ m; those of banana were long, with an average length of 40 to 45 μm. The X-ray diffraction pattern of cereal starches was type A- and that of fruits was type C-. The latter had higher pasting profiles and higher indexes of consistency than cereal starches. All starches exhibited non-Newtonian behavior. In their gels, the level of reorganization of the starches was not dependent on their source, but on their structure. Peak temperature and enthalpy of gelatinization was directly related to granule size. Their percentage of retrogradation, however, was independent of granule size and of X-ray diffraction pattern. Therefore, crystal organization depended on the conformation of the double helices of amylopectin. It is concluded that the use of starches depends on their structural organization that confers certain characteristics, regardless of the source.
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