ABSTRACT
Some plant-based oils are classified as specialty oils due to their high concentrations of bioactive components with demonstrated health benefits. In general, they are comprised of triacylglycerols with a fatty acid composition rich in unsaturates and minor components such as tocols (tocopherols and tocotrienols), carotenoids, sterols, and squalene. Such oils include nut oils (almond, hazelnut, peanut, pecan, pistachio, and walnut), seed oils (borage, flax, evening primrose, grape, pumpkin, and rosehip), cereal oils (amaranth, rice bran, and oat and wheat germ), and fruit and vegetable oils (buriti fruit, carrot, olive, and tomato). Even though the demand for specialty oils is growing at a rapid pace, they are still considered a niche market compared to the large-volume commodity oils. In general, specialty oils are sold in the form of capsules, targeting the dietary supplement market, as well as gourmet oils. Similar to commodity oils, specialty oils are also produced using conventional methods of mechanical pressing and/or solvent extraction. Even though cold pressing at temperatures below 60°C is used extensively in the specialty oil market, cold pressing is limited in terms of oil recovery and the high levels of residual oil left in the meal. On the other hand, conventional solvent extraction depends on the use of organic solvents such as hexane, which needs to be removed via subsequent evaporation. The heat applied for solvent removal may be detrimental to heat-labile bioactive components. In addition, government regulations on the use of organic solvents are getting stricter and the safety of residual organic solvents in the final product is being questioned.
