Semester of Graduation

Fall 2017


Master of Science (MS)


Nutrition and Food Science

Document Type



Cocoa is the fully fermented and dried seed of the cacao tree (Theobroma cacao L.) which has prebiotic properties, due to their high concentration of polyphenols. Therefore, the ingestion of cocoa could cause changes in the proportions of the intestinal microbiota that can influence the intestinal immune response. The objective of this study was to determine the effect of alkalization process of the cocoa bean in the diversity of the gut microbiota. The samples were “lavado” unprocessed cocoa powder, “natural” unprocessed cocoa powder, “D-11-S” as alkalized cocoa powder, “D-11-B” heavily alkalized cocoa powder, and raw cocoa “shells” and a control of fecal matter. The cocoa powders are rich in polyphenols and anthocyanins that are pH sensitive exhibiting different colors as their structure changes. Analyses of pH and color correlated to microbial diversity can help understanding for which forms of polyphenols and anthocyanins will be more active. To analyze the samples a digestion was conducted by simulating the human digestion system in vitro, with five samples and one control (fecal samples without cocoa). Microbial diversity and composition were analyzed with Illumina HiSeq with methods via bTEFAP® DNA analysis. Segments of the bacterial genome were amplified with the 515F and 806R primers specific for the universal Eubacterial 16S rRNA gene. Final operational taxonomic units (OTUs) were taxonomically classified using BLASTn against a database derived from GreenGenes/RDP/NCBI. Monte Carlo simulation was performed to detect features with significant differences. Firmicutes, Proteobacteria, and Bacteroidetes were the most predominant phyla in samples comprising >96% of all sequences (pBacteriodetes (F:B) by natural cocoa and D-11-B affected the diversity of the gut microbiota promoting a normal stable variety of OTUs. These data suggest that cocoa powder consumption aids in the prevalence of a beneficial microbiota in the human gut.



Committee Chair

Janes, Marlene