GB707454A - Process of purifying oils or fats - Google Patents

Abstract

Fatty oils and fats are bleached and simultaneously deodorized by treating them, after removal of a substantial part of their free fatty acids by saponification with alkali, with steam in vacuo at temperatures between 250 DEG and 310 DEG C. in the presence of adsorbents, the temperature being raised to such a value that a distinct bleaching of the oil occurs, and thereupon treating the thus bleached oil with bleaching or other surface-active agents. The heating treatment may be combined with a polymerization treatment by continuing the process for a time at the same, slightly lower or higher temperature, with a reduced supply of steam if desired. The oil is then cooled with continued steaming preferably to 50-90 DEG C. so as to be suitable for the further bleaching treatment. The adsorbent may remain in the oil or may be removed, and the operation is preferably effected between 50 DEG -120 DEG C. with, for example, bleaching clay. A final short deodorization with steam may follow, after filtration of the adsorbent and cooling. The oils treated may comprise fish oils, soya bean oil, palm oil, and linseed oil. The adsorbents specified comprise active carbon, kieselguhr and silica gel. The purified oils may be added to other oils and fats refined according to normal methods to increase their stability, e.g. soya bean oil, linseed oil or fish oil purified as above may be mixed with rape seed oil, ground-nut oil or olive oil. Specifications 375,381 and 707,468 are referred to.