Much of the work in the area of the physical properties of fats is aimed at detennining the relationship between triglyceride structure, crystal properties, crystallization conditions, and the macroscopic properties of fats. In finished products containing fat, some of these macroscopic properties include spreadability of margarine, butter and spreads, snap of chocolate, blooming of chocolate, graininess, smoothness, mouthfeel, water binding, and emulsion stability of spreads,among many others. The picture has remained largely incomplete because of the complex and nonlinear fashion in which these factors interact to influence a particular macroscopic property. Of gmater importance, however, is the fact that a key factor has not been included in the picture - the quantification and visualization of the microstructure of the fat crystal network. Much research in the past has been focused on establishing relationships between triglyceride structure or polymorphism. and macroscopic properties of fats, without much consideration of the microstructure of the fat crystal network. The problem with this approach is one of scale. Triglycerides crystallize to form primary crystals in particular polymorphic states. These crystals grow and aggregate into larger structures, which further associate to form larger structures, until a continuous thr-ee-dimensional network is formed. The observed macroscopic rheological properties of a system are affected by all these levels of structure, however, more directly by the level of structure closest to the macroscopic world. Not including microstructure as a variable in the equation, will undoubtedly lead to failure in the prediction of macroscopic properties. In this work we propose to use confocal laser scanning microscopy and multiple photon microscopy of Nile-Blue stained solid plastic fat samples to attempt to visualize the fat crystal network in situ. Preliminary work in our lab has shown that the Nile Blue partitions into the solid phase, negatively staining the solid triglyceride network. We will also exploit a curious fluorescence property of a naturally occurring compound that co-crystallizes with the solid triglycerides. This compound has an excitation wavelength of 330nm. Since the solid state laser in the multiple photon unit has a wavelength of 1047nm, we will attempt visualizing the triglyceride crystal network using a dure-photon excitation. Knowledge of the structure of the fat crystal network in products such as chocolate, margarine, butter and diverse spreads will allow us to better control their quality. This information is of great industrial importance.
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