Study On The Preparation Of Peanut Protein Isolation And Effects Of Peanut Red Skin On The Properties Of Peanut Protein

The two major components of peanut seed storage protein, the arachin and conarachin,differ significantly from each other in their molecular structures, functional characteristicsand nutritional properties. High-temperature peanut meals are main by-product of preparationof peanut oil, peanut protein was thermal denatured by the process of thermal treatment,which mades it hard to extract peanut protein from high-temperature peanut meals. Therefore,preparation peanut protein easily from high-temperature peanut meals is important forsatisfying the requirement of consumers and increasing the added value of peanut proteinresources. In this thesis, a simple, rapid and effective method which named jet cooking forextraction peanut protein from high-temperature peanut meals was established. In addition,this thesis adopts enzymolysis technology and the decoloring agents to improve the color ofpeanut protein, at the same time, the effects of peanut red skin on the physicochemical andantioxidant properties of peanut protein isolate and its hydrolysates and the effects of red skinon the stability and antioxidant properties of peanut protein isolate emulsion was studied. Thefollowing conclusions were drawn from this essay:(1) Jet cooking gave a37.56%of protein yield and a82.5%of NSI, solubility andemulsification also improved obviously, After jet cooking, peanut protein isolate wascompletely denatured, produced soluble aggregation, particle size is bigger, the surfacehydrophobicity increased obviously.(2) Peanut protein directly by decoloring agents, protein was easily absorbed, and afterenzymolysis can get great improvement; Alcalase enzymolysis before decolorization has thebest decolorization effect, pepsin and papain in proper order; activated carbon is in the bestdecoloring agents in decolorization effect; The results showed that high degree ofdecoloration could be obtained under the following condition: pH3.0, powered activatedcarbon1%, temperature55℃, time35min, under this condition, the whiteness was45.32andthe recovery was89.92%.(3) The hydrolysis speed of PPI with peanut red skin was slower than PPI withoutpeanut red skin; under the conditions of the same value of DH, surface hydrophobicity of PPIwith peanut red skin was less than PPI without peanut red skin; in the distribution of GPC, the peak of PPI with peanut red skin was greater than PPI without peanut red skin; peanut redskin could improve the solubility、emulsion stability and emulsifying activity of PPI and itshydrolysates; Under the conditions of the same value of DH, content of polyphenol ofhydrolysates of PPI with peanut red skin was significantly increased; content of polyphenolhad a positive correlation with antioxidant properties of PPI and its hydrolysates.(4) Peanut red skin can improve the stability of the PPI fish oil emulsion, the higher theconcentration of the peanut protein, the more stability of the emulsion; it could not formstable emulsion at high concentration of ionic strength; the red skin can not improve theability of anti-ionic; the emulsion can endure the thermal treatment but can not endure thefreezing-thawing; at the same pH value, the emulsion with red skin has a higher ζ-potentialthan the emulsion without red skin; the microstructure of the emulsion with red skin wassmaller and more equality. The smulsion system can improve the antioxidant properties of thefish oil.