SINTERING OF FAT CRYSTAL NETWORKS IN OIL DURING POST-CRYSTALLIZATION PROCESSES

Several foods contain semi-solid fats that consist of solid crystals d ispersed in a liquid oil. In oil-continuous margarine, butter, and cho colate, fat crystals determine properties such as consistency, stabili ty against oiling-out, and emulsion stability. Trends toward foods wit h less fat and/or less saturated fat create a need for understanding a nti controlling the properties of fat crystal dispersions. Fat crystal s form a network in oil due to mutual adhesion. One source of strong a dhesion is formation of solid bridges (sintering), which has been stud ied in this work through sedimentation and theological experiments. Re sults indicate that sintering may be created by crystallization of a f at phase with a melting point between that of the oil and the crystal. Generally speaking, beta' crystals were sintered by beta' fat bridges , favored by rapid cooling, and beta crystals by beta fat bridges, fav ored by slow cooling. The existence of the same polymorphic form of th e crystal and bridge indicated that solid bridges, rather than bridges formed by small crystal nuclei, were formed. A maximum in sintering a bility for an optimal sintering fat concentration occurred due to comp etition between bridge formation and other crystallization processes. Some emulsifiers influenced the sintering process. For example, monooo lein made it more pronounced, while technical lecithin had the opposit e effect.