Use of gum cordia (Cordia myxa) as a natural starch modifier; effect on pasting, thermal, textural, and rheological properties of corn starch

Abstract

Incorporation of hydrocolloid gums in native starches help to improve their pasting, thermal, rheological and textural properties along with improvement in the stability of starch gels. The use of Cordia gum is not widely studied as a starch modifier and this fact could make this study more interesting and unique. This study investigated the effects of the non-conventional hydrocolloid gum (Cordia gum) on corn starch properties. Corn starch and gum Cordia (GC) blends were prepared at different replacement levels (0%, 3%, 6%, 9%, and 12%). The effect of GC levels on pasting, thermal, rheological, and textural properties were evaluated using rapid viscoanalyzer, differential scanning colorimeter, rheometer, and texture analyzer. The presence of GC significantly increased starch gelatinization temperatures, enthalpies, peak viscosities, final viscosities, and setback viscosities. GC improved freeze thaw stability in starch. The shear rate (1/s) versus shear stress (σ) data of all samples fitted well to the simple power law model (R2= 0.97-0.99). The control had the lowest flow behavior index (n; 0.17), which increased to (0.36-0.56) with increasing GC levels. The consistency index (K) of the starch-gum blends increased with increasing GC levels. The dominance of elastic properties over viscous properties was demonstrated by G′ > G″. The magnitudes of G′ and G″ increased with increasing GC concentration. The outcomes could help to use this modification method as an alternative to chemical and enzymatic modification with respect to cost, safety, less time consumption and less requirement of process modifications.