CONTINUOUS FRACTIONATION OF FRIED OIL BY SUPERCRITICAL CO_2

摘要

Fried oils are a waste generated from food industries and restaurants that are usually discarded because oxidized lipids degrade the quality of the fried food. The development of new purification technologies has been of increasing interest over the last years, because the fried oil still contains a large quantity of triglycerides that could be recycled. Fractionation by supercritical Carbon Dioxide (SC-CO_2) might be an effective way for the purification of fried oils because SC-CO_2 can selectively separate oil components on the basis of their polarity and molecular weight. In this work we studied the fractionation of fried peanut oil by SC-CO_2 continuous fractionation. The fractionation has been carried out in a continuous packed column with an inner diameter of 17.5 mm and an effective height of 1920 mm, with the feed at about 800 mm from the top. The content of polymeric compounds (POL), triglycerides (TG) and low molecular weight compounds (LMWC) in the fractionated streams was evaluated by high-pressure size exclusion chromatography. We studied the influence of pressure (in the range 15-35 MPa), of temperature (in the range 25-55℃), on the process yield and on the composition of extracted streams. Operation conditions were optimised to separate POL and TO fractions in the separation column. Experimental results indicate that the optimal operating conditions leading to maximal TG to POL separation and maximum recovery of TG in the extract were at 35 MPa, 55℃ and at solvent to feed ratio of 50.