|SINGH, AJPAL - OAK RIDGE INSTITUTE FOR SCIENCE AND EDUCATION (ORISE)|
Submitted to: LWT - Food Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/25/2016
Publication Date: 7/28/2016
Citation: Singh, A., Geveke, D.J., Yadav, M.P. 2016. Improvement of rheological, thermal and functional properties of tapioca starch using gum arabic. LWT - Food Science and Technology. 80:155-162.
Interpretive Summary: Chemically modified tapioca starch is used in many foods as a thickening and gelling agent. Instead of chemically modifying the native tapioca starch, adding small amounts of gum arabic to the starch may provide the same, if not superior, results. When only 0.1% of gum arabic was added to tapioca starch, the viscosity (or thickness) of the mixture increased from 0.005 to 0.018 Pa-s. In addition, the flow behavior index decreased from 0.99 to 0.23 as the concentration of gum arabic in the mixture increased. These results, and others, showed that gum arabic beneficially modified the properties of tapioca starch without chemicals, and, as an added benefit, could reduce the calorific value of foods.
Technical Abstract: The addition of gum arabic (GA) to native tapioca starch (TS) to modify the functionality of TS was investigated. GA is well known for its stabilizing, emulsifying, and thickening properties. The effects of adding GA (0.1-1.0%) on pasting, rheological and solubility properties of TS (5%) were analyzed. GA has a higher molecular weight and viscosity than TS and its addition at a very small level (0.1%) to the TS raised the overall viscosity of the TS-GA dispersion. Pasting properties suggested that pasting temperature, setback property and viscosity of the TS-GA dispersion increased with increasing concentration of GA. Dynamic viscoelasticity measurements showed that that G’and G” increase in the presence of GA, suggesting a strong interaction between GA and TS amylose in the composite system. At all concentrations of GA (0.1-1.0%), the elastic modulus (G’) was greater than the viscous modulus ( G”), indicating higher elasticity, but the extent of changes, especially strength of elasticity, was higher at the higher concentrations used. The flow behavior index (n) decreased from 0.99 to 0.23 as the concentration of GA in the dispersion increased, indicating pseudoplastic behavior (n < 1). However, the consistency coefficient increased from 0.006 to 0.283 Pa/s. A strong correlation between G'' and solubility index was found showing an overall increase in viscosity and solubility of dispersion. These results show that GA beneficially modifies the rheological behavior of TS and could broaden the application spectra of native starches in the food industry.