Characteirzation And Destabilization Of The Emulsion Formed During Aqueous Extraction Of Peanut Oil

Peanut is one of the most important resources of edible oil and protein in the world. Aqueous extraction can recover peanut oil and protein simutaneously, and compared to the general enzymatic aqueous extraction, the amount of enzyme used in process is quite fewer, and the functional properties of the protein production is more comprehensive and suitable for the extensive use in food industry. So aqueous extraction oil process has attracted much attention, but it has not been realized industrialization for the difficulty of demulsification and high energy consumption.In this paper, the formation mechanism and characterization of the emulsion formed during aqueous extraction of peanut oil were studied systematically and thoroughly, revealing the mechanism of emulsion stability and completing the optimal process to carry out the destabilization of the emulsion. In order to further increase the total oil yield, the properties and destabilization of the stubborn emulsion which could not be destabilized after enzymatic treatment was studied.Then the quality of the oil extracted using aqueous extraction process was comprehensively analyzed to provide theoretical support for the study of the subsequent refining process. The specific results were as follows:Microscopic structure of the peanut oil body and the emulsion was observed with confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM). The result show dry milling of64s when the average particle size reached about48μm was adopted for aqueous processing to limit the formation of emulsion.The main components, particle size, rheological properties, as well as the zeta potential of the emulsion were also determined, and the surface protein was extracted and its electrophoresis property, hydrophobicity, emulsifying activity as well as emulsifying stability were studied to provide a better understanding of the emulsion. It was observed that the surface protein concentration was high and the oil in the emulsion were covered with proteins film to keep the oil from gathering. This could be attributed to the synergistic effect of temperature and pH during the alkaline extraction, which led to the unfolding of some large peanut protein molecules containing hydrophobic basic arachins. This consequently caused the exposure of more hydrophobic groups and enhanced the hydrophobic and emulsifying properties of the protein. Thus emulsion formation and stability was promoted.Various single and combined treatments, including freeze-thaw, thermal, high speed shear and especially enzymic treatments with protease, phospholipase and amylase were attempted to destabilize the emulsion for oil recovery. Papain can get the demulsification rate to about, and increase the free oil yield from67.32%to90.71%.The properties and destabilization of the stubborn emulsion which could not be destabilized after enzymatic treatment was studied. And90.71%of the oil in the residual emulsion could be recovered by50%ethanol washing, and the total free oil yield could be increased by about3%by this treatment.(5) The main quality indicators, fatty acid composition, vitamin E content and oxidative stability of the oil extracted using aqueous extraction process were studied. It observed that quality indicators have meet the requirements of the quality of the national level3peanut oil. So after simply and moderately refining process, we can get high-quality oil products. These advantages would improve aqueous extraction process to become the ideal alternative process.