Mechanistic considerations of polymorphic transformations of tristearin in the presence of emulsifiers

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.

Liquid Crystalline Phases in the Structuring of Food Products

“…To explain these observations it should be realized that the transformation involves the transition from a loosely packed α-modification to a tightly packed -modification. Such transitions will be hindered by the presence of foreign compounds, acting as crystal structure modifiers or as retarders of polymorphic transformations (18). It is further observed that increasing amounts of phospholipid affect the hardness of the final coagel ( Table 1).…”

Modified soybean lecithins as inducers of the acceleration of cocoa butter crystallization

“…Bowser [12] showed that the addition of PGPR or standard soy lecithin to cocoa butter produces numerous crystals of small sizes or few crystals of larger size, respectively. In general, the effect of emulsifiers on fat is associated to the development of different crystalline organizations and/or imperfections [13]. Two different mechanisms have been reported in order to interpret the influence of emulsifiers on fats crystallization.…”

Structural characteristics of crystals formed in palm oil using sorbitan tristearate and sucrose stearate

“…Some emulsifiers can delay transformations via steric hindrance, while others lead to these transformations, thus favoring polymorphic transitions. [6] Two different procedures have been reported in the literature to analyze the effect of emulsifiers on fat crystallization. The first mechanism describes the action of these additives as heteronuclei, whereby the crystallization is accelerated by direct catalytic action as impurities.…”