Process for extracting and desolventizing natural oil-containing food products with minimum structural damage

A method of desolventizing a marc resulting from an extraction of a mass of an oil-containing material with a normally gaseous hydrocarbon solvent for the oil in said material, said extraction being carried out in a closed vessel which is at least partially filled with said mass of material, said closed vessel being maintained during the extraction under a pressure at which said hydrocarbon solvent is liquefied, and after completion of the extraction, the solvent is drained from the marc while the marc remains within said closed vessel, leaving residual solvent retained in the marc, and gaseous vapors heated to a temperature above the boiling point of said hydrocarbon solvent are contacted with said marc within said vessel to desolventize the marc by volatilization of the residual solvent therein and carry the volatilized solvent from said closed vessel, the improvement of desolventizing the marc by the steps of passing the heated gaseous vapors through a first region of said vessel and the volume of said marc therein for a selected period of time sufficient to volatilize into the gaseous vapors residual solvent from the marc in said region to the desired extent;

• next, passing heated vapors through another region of said vessel and the volume of said marc therein for a period of time to volatilize into said heated vapors residual solvent from the marc in said other region to the desired extent;
• then passing heated vapors through still other regions of said vessel and the volumes of marc therein in turn as necessary to contact the entirety of said marc mass with heated vapors, the passage of vapors through each of said still other regions being of a duration sufficient to remove to the desired extent residual solvent from the marc therein;
• and when residual solvent has been removed to the desired extent from said marc as a whole, discharging the desolventized marc from said vessel.