title: Effect of gamma irradiation on rheological properties of polysaccharides exuded by A. fluccosus and A. gossypinus.
abstract: In this study, Iranian gum tragacanth (GT) exudates from Astragalus fluccosus (AFG) and Astragalus gossypinus (AGG) were irradiated at 3, 7, 10 and 15 kGy. Fourier transform infrared spectroscopy (FTIR) data showed that irradiation did not induce changes in the chemical structure of either type of gum. Although particle size distribution and both steady shear and dynamic rheological properties were considerably affected by the irradiation process, the magnitude of the effect of irradiation on each of the rheological and size variables was different for the hydrocolloids. For instance, for AGG, increasing the irradiation dose from 3 to 10 kGy, the d(0.5) and D[3,2] values were reduced by one-sixth to one-eighth fold. Colour measurement revealed that the radiation process led to an increase in the yellow index and b* values for both types of GT in powder form, but it was more pronounced for AGG samples. Irradiation led to an approximate 13-fold increase in redness in AFG. Surface and shape changes of the gum crystals were studied by scanning electron microscope (SEM) and a smoother surface for irradiated samples was detected. The notable changes in functional properties of each variety of irradiated gum should be taken into consideration before using the radiation technology as a commercial tool for sterilisation.
authors.affiliation: Department of Food Science and Technology, Faculty of Nutrition Sciences and Food Technology, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors.forename: Samira
authors.initials: S
authors.lastname: Alijani
authors.forename: Sima
authors.initials: S
authors.lastname: Balaghi
authors.forename: Mohammad Amin
authors.initials: MA
authors.lastname: Mohammadifar
mesh_terms: D027883:Astragalus Plant / Q000737:chemistry*; D003116:Color; D055119:Elastic Modulus / Q000528:radiation effects; D004548:Elasticity / Q000528:radiation effects; D005720:Gamma Rays; D008956:Models, Chemical; D010316:Particle Size; D012212:Rheology / Q000528:radiation effects*; D017550:Spectroscopy, Fourier Transform Infrared; D014144:Tragacanth / Q000737:chemistry* / Q000528:radiation effects* / Q000648:ultrastructure; D014783:Viscosity / Q000528:radiation effects
chemical_list: D014144:Tragacanth