Laboratory separation of crystals from plastic fats using detergent solution

An improved laboratory technique for isolating the solid‐fat fraction from plastic fats is described. The fat first is dispersed in an aqueous detergent solution; then the oil and solid fat fractions are separated by high speed centrifugation. To facilitate the separation, a 25% ammonia solution is added to adjust the density of the water phase to between those of the oil and the solid‐fat phase. After rinsing with cold ethanol, a solid‐fat fraction is obtained‐contaminated with only ca. 5% oil‐which can directly be used for differential thermal and X‐ray analyses. The method also can be applied for a quick determination of the solid‐fat content according to the dye dilution principle and for obtaining oil‐free fat crystals for electron microscopy.