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The fine structure of rice-starch amylopectin and its relation to the texture of cooked rice.

Radhika Reddy, K. and Zakiuddin Ali, S. and Bhattacharya, K. R. (1993) The fine structure of rice-starch amylopectin and its relation to the texture of cooked rice. Carbohydrate Polymers, 22 (4). 267-275, 50 ref..

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Starches derived from 20 rice var. containing from very low to very high total and hot-water-insoluble amylose-equivalent (AE) were fractionated by gel-permeation chromatography (GPC). Fraction I (amylopectin) and fraction II (amylose) correlated well with the insoluble-AE and soluble-AE, respectively, of the parent rice. Thus soluble-AE broadly represented the true rice amylose and insoluble-AE the iodine affinity of amylopectin. Amylopectins of 8 representative var. were debranched and fractionated by GPC to study their chain profiles. Amylopectins from the highest-AE var. had the largest proportion of long B chains and the lowest proportion of short chains, while the reverse was true for waxy rice. Other var. broadly followed this correlation between B-chain length and AE. In addition, when the 8 amylopectins were first hydrolysed with beta-amylase to remove the external chains and the beta-limit dextrins were then debranched and fractionated, the greatest drop in the amount of long B chains occurred in the highest-insoluble-AE var. and the smallest drop (nil), in waxy rice. The results suggest that highest-insoluble-AE (i.e. high-iodine-affinity) amylopectin had not only the highest amount of long B chains, but the largest proportion of these chains was in the exterior region (carrying non-reducing ends), and vice versa. Differences in cooked rice texture seemed to be related to this difference in the fine structure of its amylopectin.

Item Type: Article
Subjects: 500 Natural Sciences and Mathematics > 04 Chemistry and Allied Sciences > 30 Starch Chemistry
600 Technology > 08 Food technology > 21 Cereals > 01 Rice
Divisions: Grain Science and Technology
Depositing User: Food Sci. & Technol. Information Services
Date Deposited: 30 Mar 2016 10:05
Last Modified: 30 Dec 2016 08:17
URI: http://ir.cftri.com/id/eprint/7919

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