Effects of locust bean gum on the structural and rheological properties of resistant corn starch
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In this study, interactions between resistant corn starch (RS) (5% w/w) and locust bean gum (LBG) (0, 0.125, 0.25, 0.50 and 1.0% w/v) on the viscoelastic, pasting and morphological characteristics of aqueous dispersions were evaluated. Results showed that the storage modulus (G′), loss modulus (G′′), and apparent viscosity values of starch/gum (RS/LBG) mixtures were enhanced with the addition of LBG, and the rheograms demonstrated a biphasic behavior. RS/LBG samples were predominantly either solid like (G′ > G′′) or viscous (G′′ > G′), depending on the added concentration level of LBG. Gum addition also caused higher peak viscosity, breakdown and total set back of RS/LBG mixtures. A strong correlation between rheological and structural properties was found. Confocal laser scanning microscopy (CLSM) images confirmed the transition of starch particles from a scattered angular shape to clustered structures cross-linked by dense aggregate junction zones justifying the observed changes in rheological properties.
KeywordsCorn starch Rheology Locust bean gum Pasting properties Confocal laser scanning microscopy
The authors are gratefully indebted to Natural Sciences and Engineering Research Council of (NSERC) for the fellowship of the first author. The authors also wish to thank Dr. Pramod Pandey and Dr. Maria Briceno for helpful discussions to improve the quality of this paper.
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