Changes of Chemical Bonds in Peanut Protein High Moisture Extrusion Texturization

【Objective】In this study, the mechanisms of peanut protein high moisture extrusion texturization were explored by analyzing the changes of microstructure, chemical bonds of extrudates and peanut protein succinylated modification before extrusion. 【Method】The microstructures of extrudates were observed by scanning electron microscope. Texture properties of extrudates were analyzed by a texture profile and the chemical methods were used to determine the total sulphhydryl and disulfide bonds contents of extrudates. Peanut protein was modified by succinylation before extrusion. 【Result】The protein solubility test results shows, the solubility of peanut protein was greatly decreased with extrusion temperature increasing, but the protein solubility obviously increased when buffers contained sodium dodecyl sulphate (SDS) alone or in combination with 2-mercaptoethanol (2-ME). The results indicated that the protein which combined by non-covalent bonds increased greatly. The disulphide bond contents of extrudates slightly decreased at 140-150℃, and decreased significantly at 155℃ with the extrusion temperature increasing. When peanut protein was modified by succinylation before extrusion, the hardness, chewiness and texturized index of extrudates were significantly decreased, and the microstructure of corresponding extrudates also present changes.【Conclusion】Hydrophobic interactions and hydrogen bonds played the main function, and disulfide bonds was the second during peanut protein texturization. Some disulfide bonds might be cleaved during extrusion, and the reaction would be accelerated at higher temperatures. Succinylated modification of peanut protein before extrusion could disturb the interactions between protein molecules and hindered the fibrous structure formation during extrusion texturization.