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Rich in fat and protein, peanuts, cold pressed peanut and peanut oil and of undenatured peanut protein. However, due to the lower residual oil cold pressed peanut cake in protein content is high, limiting its application in the food industry. This thesis, cold pressed peanut cake as raw materials, ethanol extraction and hexane - the hydrous ethanol mixed solvent extraction method were used to prepared peanut protein concentrate and the mixing solvent extraction prepared peanut protein concentrate, modified, obtaining better functional peanut protein concentrate, and the last the different peanut protein structure analysis. The response surface experiment to determine the alcohol wash produce peanut protein concentrate optimum conditions: 56% ethanol concentration, extraction temperature of 54 ° C, extraction time 70min, solid-liquid ratio 1:6, extracted three times. In such conditions, the peanut protein concentrate content (dry basis) 69.01%, 2.43% crude fat, NSI value of 10.57%. Alcohol the wash production of peanut protein concentrate, residual oil, and still can not meet the food industry in more than 2%, determined by orthogonal experiments mixed solvent immersion production of peanut protein concentrate, optimum conditions for: solvent (n-hexane: ethanol ) 3.5:6.5, 75% ethanol concentration, extraction temperature 50 ℃, extraction time 60min, solid-liquid ratio 1:11, extracted four times. In such conditions, the peanut protein concentrate content (dry basis) 70.50%, 0.52% crude fat, NSI value of 20.78%. Protein concentrate prepared by two methods as NSI values ??are low, it is difficult to widely used in the food industry, peanut protein concentrate prepared on the mixed solvent bath modified peanut protein concentrate solubility can be further enhanced. The use of two modified method is: water bath heating, microwave heating. By orthogonal experiment, the optimal conditions of microwave modified: microwave heating time 60s, microwave power 480W, solid to liquid ratio of 1:12, the pH value of 9.0, the NSI peanut protein concentrate is 53.26%. Water bath heated optimal conditions: pH 9.0, heating 7min, water bath temperature of 75 ° C, the solid to liquid ratio of 1:11, the peanut protein concentrate NSI value of 72.33%. Water bath heated modification on the solubility enhancing effect is more obvious. Prepared peanut protein concentrate and modified peanut protein concentrate functional comparison. The alcohol extract of peanut protein emulsifiability, emulsion stability, water-absorbent, foaming properties are weaker than that of a mixed solvent of peanut protein concentrate, and foam stability of its oil absorption is higher than the mixed solvent prepared peanut protein concentrate. Weaker than the water bath modified peanut protein modified by microwave peanut protein concentrate, emulsifiable, water-absorbent, foaming properties, and the emulsion stability and foam stability than the water bath modified protein, both samples in the suction of aspects less. Scanning electron microscopy showed that the alcohol wash, the the mixed solvent immersion and microwave heating operations are modified with a water bath modified form of peanut protein molecules have different degrees of change. SDS-polyacrylamide gel electrophoresis showed that the raw material, an alcohol washed protein concentrate, a mixed solvent bath protein concentrate three electrophoretic bands of similar, but modified by microwave and bath modified obtained samples with their large differences , also a slight difference between the two. Further, various processes produce a sample of the protein secondary structure changes were detected by infrared spectroscopy method.
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