| In order to develop mild oil deacidification method, reduce pressure for subsequent decolorization stage, free fatty acid (FFA) was removed from soybean oil by solvent extraction. The effects of solvent type, solvent volume fraction, extraction method, oil-solvent ratio, extraction time, extraction temperature, stirring speed and extraction times on the FFA removal rate, neutral oil yield and soybean oil decolorization rate were systematically investigated. The solvent was recycled, and the quality of soybean oil before and after deacidification was analyzed. The results showed that the optimal conditions for removing FFA from soybean oil by solvent extraction were obtained as follows: 90% ethanol extraction, ratio of soybean oil mass to solvent volume 1∶ 2, extraction time 15 min, extraction temperature 30 ℃, stirring speed 600 r/min, extraction three times, and separation with sedimentation. Under these conditions, the FFA removal rate, neutral oil yield and soybean oil decolorization rate were 87.6%, 943% and 56.2%, respectively. The acid value of soybean oil decreased from 3.46 mgKOH/g to 0.43 mgKOH/g, meeting the acid value requirement of the national standard first grade soybean oil. There was no significant difference in FFA removal rate, neutral oil yield and by-product yield before and after ethanol recovery. The pigment content of soybean oil was significantly reduced after deacidification by ethanol extraction, and the color of the oil was significantly improved. In conclusion, the ethanol extraction method for removing FFA from soybean oil has mild conditions, recyclable solvents and auxiliary decolorization effect. |
