The kinetics of polymorphic transformations in monoacid saturated triglycerides and the influence caused by the presence of certain solid surfactants were investigated. Selected emulsifiers can be incorporated at the level of 10 wt% within the triglyceride, without changing the crystal lattice; on the other hand, their presence affects the heat capacity of the triglyceride and the NMR relaxation time T1. Following the polymorphic transformation both during aging and during heating in the DSC, it was observed that both the mechanism and rate of transformation of the triglyceride strongly depend on the kinetic conditions and on its own chemical structure. In conjunction with these results it also was observed that the effect of the emulsifier is strongly dependent on the transformation conditions. The kinetic effect of the additive on the solid‐solid transformation has been found to be strictly associated with its hydrophilic moiety structure; a model of molecular incorporation has been proposed which describes the arrangement of the surfactant molecules parallel to the triglyceride chains and formation of vacancies. The selectivity of the additive concerning its effect of dynamic controller of polymorphic transformations has been explained by its capacity to create hydrogen bonds with the neighboring triglycerides, which was called the “Button Syndrome.” The wide range of different additives and triglycerides used supplied a better understanding of the factors which determine the polymorphic and crystallization behavior in triglycerides.

No abstract

No abstract

Fat polymorphs influence the quality of some food and cosmetic products. Emulsifiers traditionally have been added in order to retard undesired polymorphic transformations. The present study is an attempt to understand the role of selected emulsifiers on such transformations. Tristearin was heated or aged under controlled conditions using differential scanning calorimetry (DSC) and X‐ray techniques, and the extent of transformation was evaluated in view of the possible pathways of α transforming into β. The temperature regime controls the extent of mobility of fat molecules, the local crystal imperfections and the degree of liquefaction. As a result, it dictates the kinetics of the polymorphic transformation.The surfactant added as an impurity does not have a straightforward effect, as thought previously, but rather varies with the kinetic conditions. During aging some selected solid emulsifiers will retard the α‐β transformation while others still enhance it (during heating, all of them will inhibit β form crystallization). Their effect probably is related to different crystalline organizations and the creation of imperfections. Liquid emulsifiers in any case will enhance the α‐β transformation, due probably to their weak structure compatibility with tristearin, which causes a higher mobility of triglyceride molecules.

No abstract

The polymorphic behavior of cocoa butter in the presence of several food emulsifiers serving as crystal structure modifiers was investigated. Emphasis was placed on transitions among the relatively stable forms IV, V and VI, which are significant for a confectionery industry. As known from industry work, within the series of sorbitan esters and ethoxylated sorbitan esters, the solid emulsifiers were the most efficient in retarding transition of V form into VI modification. Blends of sorbitan monostearate (Span 60), ethoxylated sorbitan monostearate (Tween 60) and Span 60‐Tween 65 used in the present study were particularly effective. Surprisingly, it was found that some combinations of emulsifiers accelerate the transition of form IV into form V. Transition of form V into form VI occurs via the solid state, and other transitions are known to take place via the liquid phase. Emulsifier was found to increase liquid fraction of the fat prior to its transition. Mechanistic considerations concerning these transitions are suggested.

Cholesterol and calcium phosphate, the latter in the form of hydroxyapatite, accumulate in atherosclerotic lesions. In this report, we demonstrate that these organic and inorganic constituents of lesions can accumulate together, closely associated in crystal agglomerates. Using the fluorescent cholesterol probe, filipin, we identified unesterified cholesterol that was associated with calcium granules in tissue sections of lesions. We also have shown that small crystallites of cholesterol can associate with preformed hydroxyapatite crystals in vitro. Scanning electron microscopy coupled with energy-dispersive X-ray analysis demonstrated the physical association of many small crystallites of cholesterol with larger crystals of hydroxyapatite. These small crystallites of cholesterol associated with hydroxyapatite stained with filipin. This contrasted with the lack of filipin staining of unassociated larger cholesterol crystals or hydroxyapatite alone. How cholesterol and calcium come to be closely associated in crystal agglomerates within atherosclerotic lesions remains to be determined.

No abstract