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Legume and Cereal Starches - Chemical Basis for Differences in their Digestibilities

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Title Legume and Cereal Starches - Chemical Basis for
Differences in their Digestibilities
 
Creator Madhusudhan, B.
 
Subject 21 Cereals
30 Starch Chemistry
22 Legumes-Pulses
 
Description Legume's and cereals contribute a major share of both
available and unavailable carbohydrates in any vegetarian
diet. Among these, starch is the principle dietary
carbohydrate (65-78% in cereals and 55-65% in legumes), and
depending upon the source the isolated starch exhibits varied physicochemical and functionality characteristics. It is known from earlier studies that the digestibility of
legume starches, both in terms of absolute amount digested
and also the rate at which it is hydrolysed, is lower (-65%) than that of cereal starches (>85%), whether in the native or gelatinized form, and that high consumption of legume-based foods leads to flatulence and other physiological discomforts. The various factors which affect starch digestibility in general, are the amylose content, starchprotein and starch-lipid interactions, extent of gelatinization and of retrogradation, shape and size (morphology) characteristics of granules and the presence or absence of any amylase inhibitors. Most commonly, the amylose content of cereal starches is 20-25% and of legume starches is -30-40%, while the remainder is due to amylopectin and other (starch) glucan fractions, if any. Thus, the overall differences in the in vitro digestibility values are primarily attributable to the nature and composition of starch per se. As there were no precise scientific data available to explain, at a molecular level,the digestibility differences, an attempt was made in the present investigation to look into these aspects more carefully. Essentially, several debranching enzymes and SE-HPLC and GPC techniques were used to elucidate the subtle structural differences between the legume [Bengalgram (Cicer arietinum) and greengram (Phaseolus aureus)] and cereal rice,(Oryza sativa) and ragi (Eleucine coracana) starch fractions (amylose and amylopectin). It was shown that the DP/CL as well as the molecular weight values of these fractions differed significantly and thus formed a molecular basis to
explain the in vitro digestibility differences.
 
Contributor Tharanathan, R.N.
 
Date 1993
 
Type Thesis
NonPeerReviewed
 
Format application/pdf
 
Language en
 
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Identifier http://ir.cftri.com/1413/1/T-1250.pdf
Madhusudhan, B. (1993) Legume and Cereal Starches - Chemical Basis for Differences in their Digestibilities. PhD thesis, University of Mysore.