Physicochemical, rheological, morphological, and in vitro digestibility properties of cross-linked starch from pearl millet cultivars

Anil Kumar Siroha,Kawaljit Singh Sandhu

doi:10.1080/10942912.2018.1489841

Abstract

ABSTRACTThe effect of epichlorohydrin (0.5%) as a cross-linking agent on physicochemical, rheological, morphological, and in vitro digestion properties of pearl millet starches from different cultivars was studied. Degree of cross-linking (DC) ranged between 40.61% and 89.75%, lower values of DC were observed for cv.HC-10 and cv.HHB-67 whereas higher values were observed for cv.HHB-223 and cv.GHB-732. Cross-linked starch from cv.GHB-732 showed the lowest amylose content, swelling power, and solubility as compared to other cultivars. Rheological properties of starches during heating showed their elastic behaviour. G′ value was much higher than the G′′ value at all frequency values for starch pastes. Plots of shear stress (σ) versus shear rate (γ̇) data for cross-linked starch pastes were fitted to Herschel-Bulkley model and yield stress (σo), flow behaviour index (n), and consistency index (K) were evaluated. Scanning electron micrographs (SEM) investigations revealed that cross-linked starch granules had slightly rough surfaceand grooves with slight fragmentations. Readily digestible starch (RDS) of cross-linked starches varied from 46.1% to 50.6%, cv.GHB-732 had the lowest value. Slowly digestible starch (SDS) and resistant starch (RS) content of cross-linked starches ranged from 34.5% to 36.4% and 13.6% to 19.4%, respectively. cv.HC-10 had the highest value for SDS content while the highest RS content was observed for cv.GHB-732. In comparison to native starches, cross-linked modification decreased SDS and RDS content whereas RS content was increased.

Highlights

Native starches have limited use due to high paste temperature, viscosity, opaqueness, higher retrogradation, and syneresis of their gels.[1]
Degree of cross-linking (DC) of cross-linked starches from different pearl millet cultivars varied from 40.6% to 89.7%, the highest and the lowest was observed for cv.GHB-732 and cv.HHB-67, respectively (Table 1)
Various workers have reported Degree of crosslinking (DC) values ranging from 51.3% to 99.1% for corn starches,[8] 60.1% for potato,[25] 35.9% to 82.4% for cassava starch[5], and 7.17 to 87.29% for wheat starches.[10]

Summary

Introduction

Native starches have limited use due to high paste temperature, viscosity, opaqueness, higher retrogradation, and syneresis of their gels.[1]. For stabilized granular structure and restricted swelling, cross-linked starch is most commonly used in food industry.[4]

Methods

Results

Conclusion