Effect of Irradiated Gum Tragacanth on Rheological Properties of Oil in Water Emulsion

Background: Emulsions are thermodynamically unstable systems that can be kinetically stable by adding substances known as emulsifiers and/or thickening agents. By respect to the functional properties of gum tragacanth (GT), and its breakage probability during irradiationtreatment, the major aim of this study was to investigate the stability of oil in water emulsion in the presence of different doses irradiated GT by respect to its viscosity and viscoelastic properties at constant temperature. Methods: The effect of irradiation treatment was studied on the rheological properties of 10% w/w oil in water emulsions systems containing 0.5% w/w GT that is irradiated at doses of 0, 3, 5 and 10 kGy that are called NIGT, GT 3, GT 5, GT 5 and GT 10, respectively. In order to monitor the effect of irradiation treatment on rheological properties, rheometer has been used. All treatments were performed three times and the data were analyzed using SPSS 16.0. Values were considered to be significantly different if p<0.05. Results: Irradiation treatment affects on rheological properties of GT containing oil in water emulsion both in steady state and oscillatory one. Increasing the irradiation dose up to 10 kGy decreases the consistency index from 1.88 to 0.076 and increases the flow behavior index from 0.42 to 0.764. Irradiation treatment also makes the systems behaves more sol like. It should be noted that these differents are dose dependant. Conclusion: Rheological properties of irradiated GT containing emulsion are dose dependant. These changes may be due to the gums structural rearrangement due to irradiation. It is necessary to apply appropriate dose by considering its desirable function.

Keywords:

Emulsions , Rheology , Food Irradiation , Tragacanth