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.
Crude rice bran oil contains about 3-4% of phospholipids. In the conventional degumming process, these were removed from the oil by using water/acid degumming techniques. However, with the advent of enzymatic degumming technology, the conventional methods are no longer followed. Enzymatic degumming generates lyso-gums in contrast to the ordinary gums recovered by conventional degumming methods. Rice bran lyso gum contains primarily lyso-phosphatidyl choline (LPC). It also contains lyso phosphatidyl ethanolamine (LPE) phosphatidyl choline (PC), phosphatidyl inositol (PI), phosphatidyl ethanolamine (PE), etc, amongst other classes of phospholipids. Till date lyso-phospholipids are produced synthetically to meet their demand and abundant use. Natural alternatives can be of great importance and proper processing of the crude rice bran lyso-gum (CRBLG) will definitely produce various modified lyso-gums having specific industrial applications in cosmetics, paint, and leather industries. The present work focuses on the processing of crude RBLG to produce various lyso-phospholipids products. Initially, bleaching of CRBLG was carried out using various oxidative bleaching agents such as hydrogen peroxide, benzoyl peroxide, and sodium chlorite. Bleached lyso-lecithin with a reduction in color from 18+ to 16 Gardner Units was obtained under optimized conditions. Processes were also developed to produce LPC enriched rice bran lyso-phospholipids as well as acetylated lysophospholipids. Acetylated RBL was obtained by enzymatic modification. The phospholipid compositions of these modified rice bran lyso-lecithins were estimated by using 31P NMR and surfactant properties were also checked for some of these modified products. Lyso-PC enrichment of about 40-50% could be achieved. Emulsion stability was significantly improved for LPC enriched products. The basic raw materials are available in bulk quantities and have less price. It is, therefore, expected that the modified lyso-lecithin products can be produced in an economically feasible method to meet the demand of various industries.
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