GB883058A - Improvements in or relating to the separation of sterols - Google Patents

Abstract

Stigmasterol and sitosterols are separated from a solid stigmasterol and sitosterol starting mixture in a process which comprises contacting the starting solid stigmasterol and sitosterols mixture with a selective organic solvent as hereinafter defined to cause selective extraction of the sitosterols from the stigmasterol, separating the solid material phase which is enriched in stigmasterol content from the organic solvent phase which is enriched in sitosterols content and continuing the extraction process in countercurrent manner, passing said solid material phase through a series of enriching stages to a stigmasterol enriched end product, and passing said organic solvent phase through a series of enriching stages in reverse order and then through a series of stripping stages from each of which is obtained a stigmasterol poor-solution and a cake stripped therefrom containing stigmasterol, said solutions and said stripped cakes travelling countercurrently with respect to each other, wherein sufficient water is added to at least one of the first two enriching or stripping stages to increase the beta-value of the said selective organic solvent and/or at least one of the said organic solvent phases is bypassed around at least one of the stigmasterol enriched cakes in such a manner as to substantially match the stigmasterol content of the solids dissolved in said organic solvent phases with the stigmasterol content of the cakes to be extracted thereby. The solvents employed are selective organic solvents having a greater affinity for the residual sterols, i.e. sitosterols and these have a relative distribution coefficient greater than 1.5 at a volume of solvent which dissolves about one-half of the total solids of a sample of the sterol mixture employed as starting mixture in the process. Representative solvents are lower aliphatic hydrocarbons, halogenated lower aliphatic hydrocarbons, and mixtures thereof, lower aromatic hydrocarbons, lower aliphatic ketones, halogenated lower aliphatic hydrocarbons, lower aliphatic ethers and lower aliphatic esters. Specification 774,466 is referred to.