Crystalline, pasting and thermal properties and antioxidant activity of starch isolated from queen sago seed by using different isolation methods such as water steeping, alkali steeping and enzymatic extraction methods were evaluated. The properties studied include, chemical composition, morphology, swelling, solubility, color, X-ray diffraction (XRD), texture, pasting (RVA), total phenolic content, antioxidant activity and thermal (DSC) properties. Among the isolation methods, enzymatic extraction method is efficient as compared to alkali and water steeping method. Enzymatically extracted sago starch (ES) showed highest yield, L* value, swelling, solubility and lower non starch components. ES formed harder gel as compared to alkali steeped sago starch (AS) and water steeped sago starch (WS). SEM showed presence of more agglomerated granular structure in AS. ES showed highest peak, trough and break down viscosity. Setback and final viscosity was highest for AS. Isolation methods affected on the total phenolic content and antioxidant activity of queen sago seed starch. Highest gelatinization enthalpy of AS was correlated with higher relative crystallinity and presence of more agglomerated structure. The queen sago seed starch isolated by enzymatic extraction method has better properties and industrial relevance.
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The authors are thankful to the Department of Food Science and Technology and Central Instrumentation Facility, Pondicherry University (Grant No. F1-17.1/2016-17/MANF-2015-17-KER-52862) for providing laboratory and instrumental facilities.