A comparison of lipid shortening functionality as a function of molecular ensemble and shear: microstructure, polymorphism, solid fat content and texture

The polymorphism, microstructure, SFC, and hardness of 24 shortening systems containing fully hydrogenated fats in dilutions of 10-25% (w/w) in soybean oil was studied, as was that of five commercially available shortenings. The mixtures of fully hydrogenated fats in soybean oil were processed using a constant cooling scheme designed to cool soybean oil at 10 degreesC/min. Each shortening system used was processed with and without shearing. Pulse nuclear magnetic resonance was used to determine the SFC of the sheared and unsheared samples. The polymorphism of the samples was determined through the use of XRD. The microstructure of the samples were obtained via the use of a high resolution polarized light microscope. An Instron cone penetrometer was used to determine the hardness of the shortening samples. It was found that molecular ensemble had a large effect on SFC, polymorphism and hardness, but that the presence or absence of shear affected polymorphism and hardness tremendously, even with identical molecular ensembles. Furthermore, SEC was found to be relatively unpredictive of final hardness, while changes in polymorphism incurred by shear could be explained from differences in the molecular ensemble of particular fat systems. In many cases, similar microstructure was not indicative of corresponding hardness behavior. (C) 2003 Elsevier Ltd. All rights reserved.