Honors Theses

Date of Award

Spring 5-8-2020

Document Type

Undergraduate Thesis



First Advisor

Carol Britson

Second Advisor

Sarah Liljegren

Third Advisor

Colin Jackson

Relational Format



The aim of this experiment is to assess how a wide range of cocoa content in different types of chocolate samples effects oral motor activity for mastication events, along with the time between consumption and swallowing. A prior study assessed individual oral motor activity using surface electromyography (sEMG) for mastication events while eating four different chocolate samples, and this information was used to determine which aspects of the masticatory process underlie differences in individual chewing behavior as well as whether subjects retain their general characteristic eating behavior across a variety of chocolate samples. The study found that with chocolate samples containing 0%, 30%, and 90% cocoa, most people preferred the sample with 30% cocoa; however, there is limited knowledge because a gradually increasing range of cocoa solids was not tested. In this experiment, the range of the cocoa content of the chocolates was increased to determine a clear relationship between cocoa content, oral motor activity and preference. By using more samples with cocoa contents between 30% and 94% and testing each type of chocolate with each subject, this experiment determines the transition points among subjects’ positive and negative reactions to increasing cocoa content in chocolate. The results of this experiment reveal that while oral processing time and facial grimace status differed significantly across chocolate types, sEMG mastication did not. Regression analysis showed a significant correlation between oral processing time and some descriptive statistic rankings including hardness, bitterness, and satisfaction for certain chocolates. I hypothesize that (1) chocolate samples with higher cocoa composition will be preferred by subjects as assessed by subject evaluation of bitterness, hardness, mouth-coating, satiation, aftertaste, and overall ranking of four samples, (2) there will be a positive correlation between cocoa composition and preference until reach a threshold is potentially reached, and (3) preference will be significantly correlated with oral motor events (e.g., sEMG activity of the masseter and suprahyoid muscles; total mastication time; facial grimace status). Earlier studies have found that faster chewing or a higher number of chews shows preference, meaning that the individual’s eating behavior increases with increasing preference. However, this study did not support these findings, as it showed an overall trend of average oral processing time increasing as cocoa content increased and average satisfaction decreased. Through the use chocolates with an increased range of cocoa contents, this experiment ultimately expanded upon previous findings, supporting the hypothesis that there is a positive correlation between cocoa composition and preference until a threshold is reached.

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Creative Commons License

Creative Commons Attribution-NonCommercial 4.0 International License
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License



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