Sintering of fat crystal networks in oil during post‐crystallization processes

Abstract

Several foods contain semi-solid fats that consist of solid crystals dispersed in a liquid oil. In oil-continuous margarine, butter, and chocolate, fat crystals determine properties such as consistency, stability against oiling-out, and emulsion stability. Trends toward foods with less fat and/or less saturated fat create a need for understanding and controlling the properties of fat crystal dispersions. Fat crystals form a network in oil due to mutual adhesion. One source of strong adhesion is formation of solid bridges (sintering), which has been studied in this work through sedimentation and rheological experiments. Results indicate that sintering may be created by crystalIization of a fat phase with a melting point between that of the oil and the crystal. Generally speaking, [~" crystals were sintered by 13" fat bridges, favored by rapid cooling, and 13 crystals by 13 fat bridges, favored by slow cooling. The existence of the same polymorphic form of the crystal and bridge indicated that solid bridges, rather than bridges formed by small crystal nuclei, were formed. A maximum in sintering ability for an optimal sintering fat concentration occurred due to competition between bridge formation and other crystallization processes. Some emulsifiers influenced the sintering process. For example, monooolein made it more pronounced, while technical lecithin had the opposite effect. JAOCS 72, 911-920 (1995).

Changes in microstructural, thermal, and rheological properties of olive oil/monoglyceride networks during storage

“…Smaller b-crystals could form bridges between larger coagel crystal clusters. The overall effect is a gluing together of the network and consequent increase in hardness (Johansson & Bergenstahl, 1995).…”

The role of physical properties data in product development

“…Between structuring fats based on either partially hydrogenated fats or palm oil/palmkernel fat-based interesterifications or straight palm oil, this factor k can, however, vary by up to 50%. This variation is not concerning the difference between primary and secondary bond type, but occurs for plastic product structures relating primarily to secondary bonds [12]. On top of this variation of the factor k as a function of composition, the time a product is subjected to shear during crystallization has a substantial influence on the product hardness.…”

Effects of temperature on water-in-oil emulsions stabilised solely by wax microparticles

“…We are not aware of any report on the use of wax particles alone as emulsifiers of oil and water, although studies exist in which their influence on the properties of surfactantstabilised emulsions has been established [4][5][6] and a very recent paper shows that Shellac wax particles are good stabilisers of aqueous foams [7]. It is also known that emulsions can be stabilised partly by triglyceride [8] or fat particles [9,10], although these are not strictly classified as waxes.…”