Effect of Temperature, pH and Some Salts on Physicochemical and Rheological Properties of Nettle seed gum (NSG)

Abstract

Nettle seed gum (NSG) or Urtica pilulifera is a novel source of hydrocolloid, in this study the physicochemical, structural, functional and rheological properties of Urtica pilulifera seed mucilage were compared with gum arabic and pectin. functional properties, water absorbance was significantly affected by temperature and with increasing temperature, water absorbance increased. In the study of urtica pilulifera oil absorbance, Urtica pilulifera had a very low oil absorbance, which can make this gum suitable for use in frying products. In the stability study, the emulsion of Urtica pilulifera mucilage was significantly higher compared to pectin and gum arabic. On the other hand, with increasing temperature, the stability of Urtica pilulifera emulsion decreased. The effect of pH on emulsion stability was also observed. Urtica pilulifera mucilage has the highest stability at pH 5. With increasing the concentration of gum, the amount of surface tension in all samples decreased and pectin gum had the highest surface tension in all concentrations. In investigating the effect of temperature and pH on particle size distribution at 70°C, pH changes had the greatest effect on particle size distribution and increased with decreasing pH, particle diameter. In the study of rheological behavior at all concentrations, with increasing shear rate, the amount of shear stress also increased and with increasing concentration, the flow behavior changed to non-Newtonian fluids or pseudoplastic. In the study of mucilage structure using FTIR, many peaks have been observed, the most important of which are related to the tensile vibrations of the hydroxyl group (fat, protein and carbohydrate), ketone groups (fat, pectin, aromatic ring with CH bond) Also to investigate the possibility of using Urtica pilulifera mucilage in foods that are exposed to low temperatures Freezing test and freezing removal were performed on it After freezing, this emulsion was unstable and completely broke.