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

Abstract

Effects of supercritical CO 2 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 ϫ 10 Ϫ12 m 2 /s. In the first 105 min, more oil was extracted as CO 2 flow increased from 1.0 to 7.5 standard L/min (slpm). Beyond 120 min, increasing CO 2 flow from 4 to 7.5 slpm produced negligible differences in amounts of extracted oil. At 2.5 slpm CO 2 flow and 45-75ЊC, 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.

Moisture Content Adjustment to Modify Texture of Reduced‐Oil Pecans

“…Full-oil and 25% reduced-oil (by SFE) pecans (Alexander et al, 1997), cv. Western Schley, were used.…”

“…AN EXPERIMENT WAS DESIGNED TO DETERmine whether adjusting moisture content re-sults in textural changes. Full-oil and 25% reduced-oil (by SFE) pecans (Alexander et al, 1997), cv. Western Schley, were used.…”

“…Mechanical pressing is an effective method of oil removal from pecans and other nuts but it destroys kernel integrity. A process to remove oil without affecting kernel structure of pecans (Alexander et al, 1997) and peanuts (Goodrum and Kilgro, 1987) uses supercritical extraction (SFE) with a fluid such as carbon dioxide. The kernel is left intact with a reduced oil content.…”

Tree nut oils

“…SFE is a widely adapted extraction or separation technique employed by the food, cosmetics, and pharmaceuticals industries (Herrero et al, 2010). Recent studies using SFE to extract oil have been conducted and optimized for various tree nuts, including almond, Brazil nut, hazelnut, macadamia (Silva et al, 2008), pecan (Alexander et al, 1997), pistachio (Sheibani and Ghaziaskar, 2008), and walnut (Oliveira et al, 2002;Salgın and Salgın, 2006;Martínez et al, 2008). It behaves as a supercritical fluid when the temperature and pressure are pushed beyond its critical points.…”

Supercritical Fluids and the Food Industry

“…Some examples of these are pecans and rice bran. A reduction in the lipid content of pecans can increase their storage life (Alexander, Brusewitz and Maness 1997). From this study it was determined that the optimum extraction conditions for pecan oil was 66.8 MPa and 75 °C.…”