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Fractionation of anhydrous milk fat using supercritical CO 2 provides various fractions of different physicochemical and functional properties that should enhance its utilization. Based on a mass transfer study of a pilot plant setup of a continuous countercurrent fractionation of anhydrous milk fat by supercritical CO 2 , economic analysis of manufacturing plants was improved. Equipment was sized for six commercial-scale plant capacities, ranging from 800 to 10,000 tonnes/yr of anhydrous milk fat. Analysis considers capital investment, annual manufacturing expenses, revenues, sales, and payback time. The equipment scale-up index was .53, which is the usual literature value. For a plant processing 10,000 tonnes/yr of anhydrous milk fat, conversion cost is $.15/kg over a base price of $1.98/kg. Such a plant would have a capital investment of $4.4million and annual manufacturing costs of $21.1million. Example selling prices are calculated assuming a desired rate of return of 20% or a payback period of 5 yr, which further adds $.11/kg to the base price and conversion cost, yielding annual sales of $22.2million. The economics of the process are attractive, even though further optimization of operating conditions has not yet been performed, primarily because of the continuous nature of the process, the heat regeneration systems designed, and the large plant capacities considered. Thus, the notion that supercritical processing is expensive may be valid only for batch or semi-continuous systems rather than for continuous large-scale systems such as those studied herein.

Using supercritical carbon dioxide (SC-CO2) as the solvent, the solubility of methyl esters, ethyl esters, fatty acids, triglycerides, and fats and oils were studied over a range of temperature and pressures. Equilibrium data from the literature were correlated using the Peng-Robinson equation of state. With the van der Waals (VDW) and Panagiotopoulos and Reid (PR) mixing rules. The data were also correlated using statistical methods and the solubilities predicted by various models were compared with experimental solubilities at the temperature and pressure conditions studied. The equation of state method provided good agreement of theory with experiment for the solubilities of fatty acids and their esters, but less so for the triglycerides, fats and oils. The statistical methods on the other hand, not only predicted the solubilities of fatty acids and fatty acid esters well, but also gave good agreement with the solubilities of triglycerides, fats and oils. Chain length, degree of unsaturation, and functional groups in compounds are known to affect the vapor pressures of these compounds which in turn influence their solubilities in SCCO2. As expected solubilities decreased in going from fatty acid esters, to fatty acids, to triglycerides.