Abstract: The rheological properties of pumpkin cloudy juice were related with its concentrations (soluble solids)and the properties of different hydrocolloids (CMC, guar gum and xanthan gum). 47°Brix of pumpkin juice concentrate with CMC exhibited pseudoplastic property, while 55°Brix and 63°Brix exhibited thixotropic property. 47°Brix and 55°Brix of pumpkin juice concentrate without gum but with guar and xanthan gum exhibited pseudoplastic property, while 63°Brix exhibited thixotropic property. When the concentration of all samples was higher than 55°Brix, pumpkin juice concentrate displayed static yield stress. The values of static yield stress were increased with the concentrations. It indicated that in the pumpkin juice concentrate a weak three-dimension network was formed by the macromolecules interaction and the small particles aggregation with each other. Therefore, it could be explained why the pumpkin juice concentrate had good cloud stability during storage and good shelf life as well.

Key words: pumpkin juice concentrate, thixotropy, pseudoplasticity, static yield stress, hydrocolloids