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Ethylcellulose-Stabilized Heat Resistant Chocolate

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Title: Ethylcellulose-Stabilized Heat Resistant Chocolate
Author: Stortz, Terri
Department: Department of Food Science
Program: Food Science
Advisor: Marangoni, Alejandro
Abstract: The ethylcellulose solvent substitution method was developed which added ethylcellulose solubilized in ethanol to molten chocolate and, after evaporation of the ethanol, produced heat resistance in the chocolate. Chocolate containing 2.17% ethylcellulose 10 cP had hardness of 18 N at 40°C measured by large deformation mechanical testing. The hardness of the chocolate was found to be dependent on the chocolate formulation and concentration of ethylcellulose, and independent of ethylcellulose viscosity. Mechanical testing on model systems revealed that polymer gelation of cocoa butter only played a minor role in the heat resistance observed. Instead, interactions between sucrose and ethylcellulose were responsible for the formation of a network within the chocolate that provided the majority of the mechanical strength and oil trapping at elevated temperatures. Atomic scale molecular dynamics simulations predicted the ability of ethylcellulose to hydrogen bond with sucrose and this was corroborated by Fourier – transform infrared (FTIR) spectroscopy. Scanning electron microscopy and mechanical testing showed the presence of an ethylcellulose - sucrose network that was able to resist deformation. Simulations predicted, and mechanical testing and FTIR, showed that lecithin, typically found at the surface of sucrose in chocolate, reduced heat resistance by impeding ethylcellulose - sucrose interactions. However, fluorescence microscopy revealed that the ethanol used to prepare the chocolate could remove some of the lecithin from the sucrose. Furthermore, ethanol dissolved a small amount of the sucrose and both of these effects positively impact heat resistance. Finally, a solvent-free method of introducing ethylcellulose to food systems was explored by the development of thixotropic ethylcellulose oleogels. It was found that thixotropy could be achieved by matching the Hansen hydrogen bonding solubility parameter of the oil phase to that of ethylcellulose. This was demonstrated with an oleogel made with 8% ethylcellulose 10 cP and vegetable oil and glycerol monooleate at a ratio of 55:45. These two methods represent novel strategies to introduce ethylcellulose to food systems and the solvent substitution method demonstrated how ethylcellulose can be used to provide structure in foods.
Date: 2014-08
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