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Información tecnológica

On-line version ISSN 0718-0764


ACOSTA, Harold A; VILLADA, Héctor S; TORRES, Gerardo A  and  RAMIREZ, Juan G. Surface Morphology of Sour Cassava and Native Potato Thermoplastic Starches by Optical and Atomic Force Microscopy. Inf. tecnol. [online]. 2006, vol.17, n.3, pp.63-70. ISSN 0718-0764.

An evaluation was made of the surface morphology of thermoplastic starches (TPS) from sour cassava and native potato, extruded with a single-screw extruder, using high-resolution optical microscopy (OM) and atomic force microscopy (AFM). Samples of sour cassava starch and native potato starch and glycerine, were processed at 1200C and 50 rpm, producing extrudates which were cut into thin films for observation by OM and AFM (intermittent contact mode). Native potato starch showed large ovoid granules, while sour cassava starch revealed enzyme attack due to natural fermentation. The TPS had smooth and rough surfaces, depending upon granule size and shape, starch fermentation, and plasticizer content. Native potato TPS presented few smooth surfaces by OM and high roughness by AFM. The opposite was observed with sour cassava TPS, which had experienced some previous natural fermentation. These findings contribute to prediction and understanding of microstructural, mechanical and textural properties of thermoplastic starches.

Keywords : surface morphology; starches; optical microscopy; atomic microscopy.

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