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

Madhusudhan, B. (1993) Legume and Cereal Starches - Chemical Basis for Differences in their Digestibilities. PhD thesis, University of Mysore.

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Abstract

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.

Item Type:	Thesis (PhD)
Uncontrolled Keywords:	Legume starches Cereal starches Digestibility characteristics chemical characteristics
Subjects:	600 Technology > 08 Food technology > 21 Cereals 500 Natural Sciences and Mathematics > 04 Chemistry and Allied Sciences > 30 Starch Chemistry 600 Technology > 08 Food technology > 22 Legumes-Pulses
Divisions:	Dept. of Biochemistry
Depositing User:	Food Sci. & Technol. Information Services
Date Deposited:	21 Sep 2007 08:44
Last Modified:	28 Dec 2011 09:30
URI:	http://ir.cftri.res.in/id/eprint/1413

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