A Novel Method to Assess Consumer Acceptance of Bitterness in Chocolate Products

Open Access
- Author:
- Harwood, Meriel Louisa
- Graduate Program:
- Food Science
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- March 22, 2013
- Committee Members:
- John E Hayes, Thesis Advisor/Co-Advisor
- Keywords:
- sensory evaluation
rejection thresholds
chocolate
food science
cocoa
polyphenols - Abstract:
- Sensory science provides powerful tools for investigating consumer preferences. Chocolate is a product that comes with a host of special considerations when applying sensory evaluation techniques. Refinement of the methodology, analysis and application of a recently developed method, rejection thresholds, to chocolate products, was the focus of this thesis work. Specifically, rejection thresholds for an added bitter compound (sucrose octaacetate, SOA) were determined in chocolate-flavored fluid milk, milk chocolate-flavored compound coating, and chocolate ice cream. Bitterness was investigated because it is a necessary component of chocolate flavor at low levels but can become objectionable at higher levels. Responses were analyzed based on participant groupings by self-reported preference for milk or dark chocolate. In all three matrices, the group preferring dark chocolate tolerated significantly more SOA than the group preferring milk chocolate. Chocolate milk acted as a model system in which analysis by sigmoid dose-response function was illustrated. In compound chocolate and chocolate ice cream, use of the method in more complex food systems was demonstrated. Finally, rejection thresholds for cocoa powder produced from under-fermented cocoa beans (high cocoa flavanol (CF) natural cocoa powder) was determined in semisweet solid chocolate. This threshold is of interest to the confectionery industry as recent research has focused on potential cardiovascular health benefits from naturally occurring cocoa polyphenols, the content of which is higher in cocoa products subjected to limited fermentation. No significant differences were observed between groups preferring milk chocolate or dark chocolate in this study. The group rejection threshold was 80.7% of the non-fat cocoa solids coming from the high CF natural cocoa powder in a semisweet chocolate.