Structure and Viscoelastic Properties of Starches Separated from Different Legumes

Abstract

A comparison between the morphological, structural, thermal and viscoelastic properties of starches separated from pigeon pea, chickpea, field pea, kidney bean and blackgram was made. The shape of the starch granules in the different legumes varied from oval to elliptical or spherical. X-ray diffraction of the legume starches indicated a typical C-pattern (mixture of A-and B-type). Granules of blackgram and pigeon pea starch had a higher degree of crystallinity than those of field pea and kidney bean starches. Apparent amylose content of field pea, kidney bean, chickpea, blackgram and pigeon pea starch was 37.9%, 36.0%, 34.4-35.5%, 32.9-35.6% and 31.8%, respectively. Distribution of isoamylase-branched materials among the starches revealed that the proportions of long and short side chains of amylopectin ranged between 13.6-18.5% and 41.7-46.5%, respectively. Field pea and kidney bean starch had the highest apparent amylose content and the lowest amount of long side chains of amylopectin, respectively. Blackgram and pigeon pea starch possessed higher proportions of both long and short side chains of amylopectin than field pea and chickpea starches. The onset, peak and conclusion temperatures of gelatinization (T o T p and T c , respectively) were determined by differential scanning calorimetry. T o and T c ranged from 59.3 to 77.37C, 66.8 to 79.67C, 55.4 to 67.67C and 68.3 to 69.37C, respectively, for chickpea, blackgram, field pea and kidney bean starch. The enthalpy of gelatinization (DH gel ) of field pea, kidney bean, chickpea, blackgram and pigeon pea starches was 3.6, 3.0, 2.6-4.2, 1.6-1.7 and 2.6 J/g, respectively. Pastes of blackgram and pigeon pea starches showed lower storage and loss shear moduli G 0 than field pea, kidney bean and chickpea starches. The changes in moduli during 10 h at 107C revealed retrogradation in the order of: field pea. kidney bean. chickpea. blackgram. pigeon pea starch. In blackgram and pigeon pea starches, the lower proportion of amylose plus intermediate fraction and higher proportion of short and long side chains of amylopectin are considered responsible for the higher crystallinity, gelatinization temperature and enthalpy of gelatinization.

Effect of triple retrogradation treatment on chickpea resistant starch formation and its characterization

“…Similar observations for starches from Indian chickpea cultivars have been reported by Singh et al (2004). The shape of the starch granules in the different legumes varied from oval to elliptical or spherical (Singh et al 2008). Triple retrogradation influenced the granule morphology of NCPS.…”

Seed Protein and Starch Qualities of Drought Tolerant Pigeonpea and Native Tepary Beans

“…Tepary starch values from our study were in agreement with the values obtained by Abbas and Berry (1986) for amylose content of 30.7% and gelatinization temperature range of 70.5-84 o C with mean diameter of 33.5 microns of spherical to oval granules. The WBC trait and other thermal properties of pigeonpea were supported by Eltayeb et al (2012), Singh et al (2008) and Acevedo et al (2013) with two endothermic peaks at 80-89 o C and 96-100 o C. The black tepary bean has lowest gelatinization energy compared to white and brown varieties with an exception white cultivar TB #2 with very low gelatinization energy. The cultivar TB #2 was observed with high amylose content and amylose/amylopectin ratio with small granule size which was supported by the factors influencing the gelatinization temperatures and dissociation of starch chains due to interaction with water (Lawal, 2008;Kaur et al, 2010).…”

“…The extraction process in brown colored tepary (TB #4) might have influenced increased amylopectin due to reduced crystallinity but the crystallinity was unaffected by extraction process in TB #29 another brown colored variety (Table 4 & 5). In pigeonpea and tepary bean cultivars, the high amylose and amylopectin contents, were responsible for high crystallinity and high gelatinization temperature and enthalpy of gelatinization as explained by high proportion of short and long side chains of amylopectin (Singh et al, 2008).…”

Pulses: an overview

“…Pulse starch is consisted of amylose and amylopectin, and wide variation in amylose content in pulse starches has been reported (Tiwari and Singh 2012). Starches from various pulses have different physicochemical, pasting and technological properties (Singh et al 2008). Pastes formed from pulse starches were found to have high retrogradation tendency and are hard to swell and rupture during cooking as compared to cereal starches (Singh et al 2008;Singh 2010).…”

“…Starches from various pulses have different physicochemical, pasting and technological properties (Singh et al 2008). Pastes formed from pulse starches were found to have high retrogradation tendency and are hard to swell and rupture during cooking as compared to cereal starches (Singh et al 2008;Singh 2010). Their high stability towards mechanical shearing and heat makes them useful in number of food application and were considered to be a good alternate to replace crosslinked starches (Singh 2010).…”