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Title:Impact of emulsifiers on physical, sensory, and microstructural properties in formulated dark chocolate with an innovative educational approach
Author(s):Tisoncik, Melissa A.
Advisor(s):Engeseth, Nicki J.
Department / Program:Food Science & Human Nutrition
Discipline:Food Science & Human Nutrition
Degree Granting Institution:University of Illinois at Urbana-Champaign
fat bloom
high school food science education program
Abstract:Dark chocolate has both a complex flavor profile and compositional matrix consisting of sugar and cocoa particles dispersed in a continuous phase of cocoa butter. The crystal structure of cocoa butter contributes to both the smooth mouthfeel and melting properties of chocolate that are favorable characteristics as perceived by consumers. Chocolate has a long shelf life of about a year; however, during storage structural changes occur, which may lead to development of fat bloom or sugar bloom, either of which compromises textural and visual quality. Due to unique interactions between structural lipid polymorphs in cocoa butter, quality parameters of chocolate such as texture and flavor release are impacted by the structural alterations during storage. Previous research in our laboratory involved characterization of physical, structural and microstructural properties of chocolate, dramatically affected by storage at different temperatures and with ranging relative humidity values. Temperature cycling of chocolate led to fat bloom formation and also had a dramatic impact on quality parameters. Some changes observed were speculated due to breakdown of emulsifier in the formulation. Thus, my research was focused on characterization of the impact of emulsifier type and concentration on fat bloom formation, physical, sensory, and microstructural properties in formulated dark chocolate. Three different emulsifiers were used in this study: soy lecithin, polyglycerol polyricinoleate (PGPR), and ammonium phosphatide. Chocolate was formulated with 0.2% or 0.5% emulsifier, conched/refined, tempered, and molded in the laboratory. Sample storage treatments included temperature cycling and long term storage. Instrumental analyses were utilized to evaluate lipid polymorphism, fat bloom formation, texture and sensory perceptual changes in chocolate. Texture and flavor of samples in long term storage were evaluated by a descriptive analysis panel. Temperature cycling significantly impacted appearance and texture in samples. Specifically, samples cycled at 34°C had increased whiteness index, and were harder than samples cycled at 37°C, which experienced dramatic changes of dimension and surface roughness. Samples stored at 37°C recrystallized into polymorph V and contained characteristics similar to untempered chocolate. Chocolate formulated with PGPR had the greatest impact on textural, melting, and physical properties undergoing long term storage and temperature cycling. Increased concentrations of all emulsifiers had the greatest impact on textural, physical, and melting properties in samples. Chocolates stored at 34°C experienced polymorphic transition to form VI, experienced increased hardness and surface roughness, and were perceived as hard, grainy, crumbly, had longer melt time, left a dry mouthfeel, and had a bland, chalky flavor. Sensory study results indicated samples stored at ambient temperature were not visually or texturally compromised and were creamy, cohesive, melted quicker, left a fatty mouth coating, and had a chocolaty, roasted, bitter, and sweet flavor. Sensory results indicated the type of emulsifier used in formulation did not have a significant impact on texture or flavor attributes assessed by panelists. An innovative educational effort to recruit bright, science-minded high school students to the field of food science complimented my research on lipid polymorphism and the role of emulsifiers in chocolate. The 2009 Chocolate Food Science Education Program taught students who may not have been exposed to food science about the many facets of this exciting field through the study of chocolate. Students learned about the concentrations of food science such as chemistry, microbiology, safety, processing, product development, sensory science, nanotechnology, and nutrition. Experiential learning sessions were taught through means of lectures, demonstrations, activities, field trips, research, and interactions with faculty, staff, graduate students, and industry professionals. Evaluation of the program documented that it was a beneficial program for participants and a powerful educational recruitment tool for future food scientists. Success of this experiential learning program will serve as a model for creative efforts of recruitment to fields that need more visibility at the high school level.
Issue Date:2010-05-18
Rights Information:Copyright 2010 Melissa A. Tisoncik
Date Available in IDEALS:2010-05-18
Date Deposited:May 2010

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