Supercritical Carbon Dioxide Extraction of Vegetable Oils: Retrospective and Prospects

Abstract

Supercritical carbon dioxide (SC-CO 2 ) extraction is projected as one of the most viable alternatives to conventional hexane extraction due to its density-dependent solvent power, low viscosity, moderately high diffusion coefficient, and low-temperature operative conditions. Demands for retention of bioactive compounds in oils like wheat germ oil, rice bran oil, almond oil, etc., are increasing and that can be easily met up by this alternative solvent. Solvent extraction of oils rich in polyunsaturated fatty acid, like flaxseed oil, microbial oil, etc., is highly sensitive. Prolonged heating during removal of solvent often leads to degradation of essential fatty acids. As the phase change is done by changing the pressure, the use of SC-CO 2 overcomes such issues. It is quite evident that degumming, one of the processing steps in refining of vegetable oils, will not be required if SC-CO 2 is used for extraction. Moreover, in some other cases, bioactive compounds will be retained in the de-fatted meal and can be recovered with better purity. All these factors will add to the overall economy. A detailed review of the application of SC-CO 2 for the extraction of vegetable oils-the initial reports, current status, and future prospectsis presented in this paper. Practical applications:In recent years, the oils and fats industry has gone through several technological advancements and the most important of them was shifting to physical refining process from highly polluting chemical process. The industry may see another major change in the extraction process in the near future. Hexane has been enlisted as a hazardous air pollutant as per the Clean Air Act, 1990. Recent reports show that hexane may have some role even in ozone layer depletion. Scientists are looking forward to alternatives. SC-CO 2 has emerged as one of the most suitable alternatives. The large capital investment required for the installation of SC-CO 2 -based extraction plants was a major drawback. However, ready availability of critical machineries and advancements in terms of automation has brought down the capital expenditure significantly. The utilization of superior quality by-products generated by the process of SC-CO 2 extraction may be an added advantage for the overall economy of the process.

Effect of Moisture and Oil Content in the Supercritical CO2 Defatting of Hermetia illucens Larvae

“…Since the emerging insect industry is growing according to sustainability principles [17,18], environmentally clean processes for larvae defatting are also demanded. In this respect, supercritical fluid extraction (SFE) using carbon dioxide (CO 2 ) is a well-known technology for the defatting of vegetal materials [19] due to the high selectivity of supercritical CO 2 to extract lipid compounds. In addition, CO 2 is completely removed after the extraction, allowing the production of solvent-free oils, minimizing oil post-treatment.…”

Supercritical Carbon Dioxide Extraction Process for Hibiscus taiwanensis S. Y. Hu and Tyrosinase Inhibitory Activity of Its Extract

“…Therefore, there is an urgent need for a more advanced new technology with less environmental pollution and less damage to functional components. The supercritical carbon dioxide extraction [12][13][14][15] is a green, efficient, and highly selective extraction method, and its extraction at near room temperature can effectively protect the functional components from being destroyed. The principle of the method [12][13][14][15] is to use the varying dissolving effects of natural products in supercritical carbon dioxide to separate these products.…”

“…The supercritical carbon dioxide extraction [12][13][14][15] is a green, efficient, and highly selective extraction method, and its extraction at near room temperature can effectively protect the functional components from being destroyed. The principle of the method [12][13][14][15] is to use the varying dissolving effects of natural products in supercritical carbon dioxide to separate these products. In the supercritical state, the supercritical carbon dioxide is contacted with the substance to be separated, so that it can selectively extract the components of varying polarity, boiling points, and molecular weights in turn.…”

“…The supercritical carbon dioxide extraction method has the following features [12][13][14][15]. First, the extraction can be conducted at close to room temperature (35-40 • C) and in the atmosphere of CO 2 , which effectively prevents the oxidation and loss of heat-sensitive substances.…”