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Molecular degradation of starch during extrusion cooking of rice.

Manisha, Guha and Zakiuddin Ali, S. (2002) Molecular degradation of starch during extrusion cooking of rice. International Journal of Food Properties, 5 (3). 509-521, 22 ref..

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Abstract

Macromolecular changes occurring in starch during extrusion cooking of rice were studied at extruder barrel temp. of 80-100 or 120C. In addition, effect of amylose content on starch degradation during extrusion was evaluated using rice cultivars of varying amylose contents, namely IR64, Pojobora and Agonibora of amylose contents 28.6, 22.3 and 5.0 g/kg, respectively. Rice starch was fractionated into 2 major fractions using Sepharose CL-2B gel permeation chromatography, fraction I of high mol. wt. and fraction II of lower mol. wt. Fractions I and II were identified as amylopectin and amylose, respectively. Each fraction was complexed with iodine and the absorption max. was determined spectroscopically. Extrusion cooking of rice degraded the amylopectin fraction of starch. The extent of degradation increased with increasing severity of extrusion conditions. The absorption max. of the amylopectin-iodine complex increased after extrusion cooking; this increase was greater in the non-waxy cultivars. It is suggested that these results may help produce better quality extruded rice products through selection of appropriate rice cultivars and system parameters.

Item Type: Article
Uncontrolled Keywords: AMYLOSES-; DECOMPOSITION-; EXTRUSION-; RICE-; STARCH-; TEMPERATURE-; CV-; DEGRADATION-; EXTRUSION-COOKING; RICE-STARCH; TEMP.-
Subjects: 600 Technology > 08 Food technology > 21 Cereals > 01 Rice
600 Technology > 08 Food technology > 05 Processing and Engineering
Divisions: Grain Science and Technology
Depositing User: Somashekar K.S
Date Deposited: 08 Jul 2011 09:08
Last Modified: 08 Jul 2011 09:08
URI: http://ir.cftri.com/id/eprint/6356

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