Dynamic rheology of structural development in starch/decolourised hsian-tsao leaf gum composite systems

Lai, Lih-Shiuh; Liao, Chih-Lun

Dynamic rheology of structural development in starch/decolourised hsian-tsao leaf gum composite systems

2002

Lai, Lih-Shiuh | Liao, Chih-Lun

The gelling process of decolourised hsian-tsao leaf gum (dHG)/starch mixtures was monitored as a function of starch/gum ratio and starch type using a dynamic rheometer. It was found that the gelling process followed first-order kinetics. At starch/gum ratios of 5:1, 4:2 and 3:3, dHG interacted with starch synergistically, resulting in a marked increase in storage modulus (G′). Both the gelling reaction rate constant and plateau G′ value as a function of starch/dHG ratio showed a maximum at a certain starch/gum ratio. These results indicated that a suitable starch/dHG ratio could facilitate the formation of a three-dimensional network structure and the conversion of chains in the sol fraction into a gel. The maximum G′ value reached depended on the unique chemistry of each starch. Mixed systems with tapioca starch generally showed lower plateau G′ values than mixed systems with wheat or corn starch, possibly owing to the lower amylose content of tapioca starch.

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