EXTRACTION KINETICS OF VEGETABLE OIL USING PRESSURIZED LIQUID EXTRACTION (PLE) WITH ETHANOL IN INTERMITTENT PROCESS

Pressurized liquid extraction (PLE) consists of solvent extraction at high temperatures and pressures. This favors the extraction, as it decreases the viscosity and increases the solvent diffusivity, promoting an increase in mass transfer and, consequently, in the extraction yield. PLE is considered a green technology as it uses low amounts of solvents when compared to conventional methods. In addition, the use of ethanol, a safe solvent for health, is also less aggressive to the environment. This technique has been shown to provide more efficient extraction and faster extraction kinetics (oil reduction in the matrix). The use of ethanol in this experiment appears as a substitute for the solvent normally used in the extraction of vegetable oils, hexane, a toxic solvent that is not safe for health. In an optimized process, PLE with ethanol can present similar efficiency to extraction with hexane, provided that it consumes less solvent. Thus, a study of the kinetics of the extraction process for different sources of vegetable oils using ethanol is important to direct future large-scale production using green technology. In this study, the extraction kinetics of soybean, sunflower and rice bran oils were evaluated in an intermittent extraction process using cells of different sizes for each matrix. For the extraction of soybean oil, 40 g of rolled soybeans were used in a 100 mL cell, for sunflower 20 g of crushed grains for a 66 mL cell and rice bran, 10 g of rice bran treated enzymatically in a 34 mL cell. The solvent used was ethanol and the extractions were carried out at 70, 75, 80 and 85 °C. Twelve extractions were performed with a static time (solvent contact time with matrix) of 10 min, totaling 120 min. The solvent was recovered by evaporation and the mass of oil extracted at each collection was weighed. For comparison purposes, the mass ratio of oil/solvent (O/S) was calculated and it can be observed that the behavior of the extractions was the same, with the concentration decreasing with time. The behavior of the extraction kinetics for sunflower oil and rice bran were the same for different temperatures, however, for soybean oil it can be noted that as the temperature was increased, there was an increase in the amount of extracted oil. At 85 °C, soybean had an initial concentration of 0.077 g of oil/mL, sunflower started with 0.124 g of oil/mL, while rice had an initial concentration of 0.065 g of oil/mL. For the three temperatures studied and for the 3 matrices, the largest amount of oil was extracted in the first 40 min of the process. The results show that the extraction process can be interrupted at this point, saving solvent and energy. This study also showed that regardless of the matrix used (Soybean, Sunflower or Rice) the behavior is the same, with an increase in the O/S ratio with time showing a rapid decrease in the O/S ratio in the first 40 min and a slow decrease in the two thirds. extraction ends.