Pecan Oil Recovery and Composition as Affected by Temperature, Pressure, and Supercritical CO2 Flow Rate

Effects of supercritical CO₂ flow rate, extraction temperature, and pressure were studied on oil recovery, fatty acid composition, and factors that control solute extraction from intact pecan halves. After an initial solubility dominant period, extraction was influenced by diffusion of oil from within the pecan. The effective diffusion coefficient was 9.76 × 10^-12 m²/s. In the first 105 min, more oil was extracted as CO₂ flow increased from 1.0 to 7.5 standard L/min (slpm). Beyond 120 min, increasing CO₂ flow from 4 to 7.5 slpm produced negligible differences in amounts of extracted oil. At 2.5 slpm CO₂ flow and 45–75°C, the oil extracted increased by 60% when pressure increased from 41.3 to 55.1 MPa and yielded slightly more at 66.8 MPa. Temperature, pressure, micrometering valve temperature, cultivar (but not extraction time) affected fatty acid (palmitic, stearic, oleic, linoleic, and linolenic) composition of pecan oil.