| abstract |
A process and system for extracting a solute from a solid material, such as oil from oil-bearing foodstuffs, utilize a substantially tubular membrane filter to separate a mass of the extracting medium and the foodstuffs into a miscella and foodstuffs of reduced oil content. In a batch or continuous process, after each extracting stage, the mass from the extraction vessel is conveyed to a membrane filter, which has pores along its cylindrical walls suitably sized to allow a miscella to pass as the permeate, while causing the foodstuffs of reduced oil content to be conveyed axially along the tubes and out of its ends as the retentate. In a continuous process, extractor cells, or stages, consisting of an extraction vessel, pump, and membrane filter, are used in sequential stages, preferably using a miscella from the subsequent stage as the extracting medium. In a batch process, miscella storage tanks may be used to store miscella from the final stage for use in the next batch. In either case, only miscella having the highest oil content, namely the miscella from the first stage, is conveyed to a separator for recovery of the oil. Of particular value is the use of this process or system in extracting oil from foodstuffs which are in the form of powders, have high oil content, or are sensitive to heat. |