Effects Of Glucono-Delta-Lactone (Gdl) On Pasting, Rheological And Textural Properties Of Waxy Rice Starch

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Date
2020-07
Authors
Mohd Rafi, Najihah
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Publisher
Universiti Sains Malaysia
Abstract
Glucono-delta lactone (GDL) is a weak acid and it is easily soluble in water. Research focused on addition of GDL on starch is very limited and to the best of our knowledge it has not been reported in the literature. Thus, the current study has been conducted to study the effects of GDL addition on pasting, rheological and textural properties of waxy rice starch. Pasting properties were analysed using rapid visco analyser (RVA). The addition of GDL solution was found to increase the peak viscosity and breakdown viscosity of the waxy rice paste. When the GDL concentration increased, it was found that trough viscosity, final viscosity and setback viscosity decreased progressively. Next, steady-state flow and oscillatory analyses were carried out to study the rheological properties of waxy rice starch. For steady-state flow analysis, when shear rate increased, addition of GDL solution decreased the viscosity of the waxy rice paste and also resulted in a decreased of thixotropic value. The waxy rice pastes exhibited a non-Newtonian and shear thinning flow behaviour For oscillatory analysis, G’ and G’’ values increased with increasing frequency, and G’ was much higher than G’’ at all frequency values in increasing GDL solution. From the back extrusion analysis, it was found that waxy rice paste prepared with 0.03% w/v GDL solution resulted in a progressive decreased in firmness, consistency, cohesiveness and index of viscosity over the storage. It showed that waxy rice flour pasted with GDL exhibited less tendency of retrogradation.
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Keywords
Glucono-Delta-Lactone (Gdl) , Rice Starch
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