Study On The Process Of Extrusion Pretreatment Of Corn Germ With Semi-wet Milling For Solvent Oil Extraction

The method of orthogonal rotation combination test design of four factors and five levels was applied to discuss the principle of the influence of parameters of extrusion system upon research indexes in this paper. These parameters include the moisture of material, the speed of the screw, the temperature of the barrel, and the diameter of the die nozzle. Above indexes include the ratio of the residual oil, the value of NSI, shearing strength, volume weight of the extrudate and the moisture of the extrudate. The optimum parameters of extrusion system are as follows:moisture of material W=12%, extrusion temperature T=105℃, speed of screw n=185r/min, diameter of die nozzle is φ=9mm×3.The quality of the maize oil was analyzed, include iodine value, acid value, peroxide value, saponification value. The result of the analysis of maize oil was as follows:iodine value125g/100g, acid value0.4mg/g, peroxide value5.1mmol/kg, saponification value189%.The fatty acids in the two kinds of maize oil were esterified and analyzed by GC.4fatty acids were separated and identified. Of them the majority fatty acids were: methyl palmitate, methyl linoleate, methyl oleate and methyl stearate, and their concentrates were:13.27%,56.47%,28.51%and1.84%. The recovery ratios of fatty acids in maize oil were ranging from92.3%to94.4%.The good sensitivity and recoveries confirmed that this method could be used for the analysis of fatty acids in maize oil.