Phase relations pertaining to the solvent winterization of cottonseed and peanut oils in acetone

Abstract

Summary and Conclusions Systematic physical chemical data on the solventwinterization behavior of cottonseed and peanut oils with acetone have been obtained which should serve as a basis for selecting the conditions necessary for the effective solvent winterization of these oils in acetone. Cottonseed and peanut oils are only partially miscible with acetone below certain temperatures which have been determined. In peanut oil this phenomenon may interfere with the winterization process within a certain range of concentrations. For cottonseed oil however the separation into two liquid phases does not occur until some 5°C. below the temperature required for adequate winterization. Complete data for a 3‐hour holding‐time have been obtained for three cottonseed oils ranging in iodine value from 106.1 to 116.4. Tables and graphs have been constructed to show the effect of oil‐solvent ratio, chilling temperature, holding‐time, agitation, and iodine value of the original oil on the percentage of solid removed and on the degree of winterization and iodine value of the winterized oil. Similar data have been obtained for a refined peanut oil insofar as possible without interference from separation into two liquid phases. It seems probable that if acetone were used as the winterization solvent for peanut oil, the separation into two liquid layers and the sensitivity of this phenomenon to moisture might be a source of processing difficulties especially if filtration instead of centrifugation were used to separate the solid from the supernatant.

Liquid‐liquid phase separation in acetone solutions of palm olein: Implications for solvent fractionation

“…4B, which would seem to confirm the existence of a binodal region. In this figure are plotted published data for cottonseed oil and groundnut oil [4], which show a similar relationship. Given the number of points, it is not possible to determine the temperature, T C , above which all mixtures of oil and acetone would be completely miscible.…”

“…However, studies in the past show that cottonseed oil and peanut oil solutions in acetone will undergo liquid-liquid phase separation and that this will occur at increasing temperature as the water content of the system is increased [4]. Similar observations have been made for soybean oil and linseed oil in acetone [5], and ternary phase diagrams for cottonseed oil-acetone-water systems have been published [6,7].…”

“…Liquid-liquid phase separation temperature of palm olein in acetone as a function of (A) water at various oil concentrations and (B) oil concentration at 0% water compared to cottonseed oil and groundnut oil data from Ref. [4].…”

“…Although liquid-liquid phase separation has been observed in solutions of edible fats in solvent [4][5][6][7], little has been reported since the 1950s. However, oiling out is commonly seen in protein solutions, some polymers and, more recently, for small molecules [8][9][10][11].…”

Phase relations in the solvent winterization of molecularly rearranged peanut oil and cottonseed oil

“…It has recently been shown that improved crystals can be obtained from acetone and from a solvent mixture consisting of 85 parts by weight of acetone and 15 parts of hexane and that these solvents have other advantages over hexane (2,3,7). The filtration behavior when hexane is the solvent is very unsatisfactory, especially for peanut oil.…”