Comparison of Polyphenol Concentration and Composition between Genetically Diverse Cacao (Theobroma cacao L.) Accessions Selected for High Yield

Abstract

There is abundant evidence that consumption of cacao and dark chocolate promotes human health and that the main cacao components contributing positive health effects are polyphenols. The polyphenols in cacao bean constitute 12–18% dry weight of the whole bean and are predominantly catechins (37% w/w), procyanidins (58% w/w) and anthocyanins (4% w/w). Variation in cacao polyphenol composition and concentration can result from differences in genetic backgroud, agro‐environment and cultural practices. It is therefore important to consider several factors when selecting cacao seed (beans) for research investigating the mechanisms underlying its health benefits. In this study, dried unfermented seeds of five different cacao clones (TARS‐9, TARS‐14, TARS‐27, TARS‐30, TARS‐31) were obtained from USDA‐ARS Tropical Agriculture Research Station (TARS) located in Mayaguez, Puerto Rico. These clones were developed through controlled‐pollinated hybridization for improved agronomic performance, specifically high yield. Prior sensory evaluation of 65% chocolate made from these clones revealed that each conferred distinct profiles in bitterness. We thus hypothesized that differences in polyphenol profiles would exist between these clones. To test this hypothesis, total polyphenols, total flavan‐3ols, polyphenol extraction yield, and qualitative flavanol profile were compared between the five cacao clones. TARS‐27 had the lowest total polyphenol concentration (36 ± 1.2 mg gallic acid equivalents/g cacao bean) (mean ± STDEV), whereas TARS‐14 showed highest concentration (66 ± 4.7 mg gallic acid equivalents/g cacao bean). For total flavan‐3‐ols, a similar trend was observed; TARS‐27 showed the lowest concentration (42.3 ± 1.1 mg procyanidin B2 equivalents/g cacao bean) with TARS‐9 having the highest concentration (76.7 ± 4 mg procyanidin B2 equivalents/g cacao bean). Polyphenol extraction yield (cacao extract weight/cocoa bean weight) differed among clones ranging from 0.1–0.16. Qualitative flavanol profiles obtained using normal‐phase high‐performance liquid chromatography (HPLC) indicated that mean degree of polymerization (mDP) of polyphenols is likely similar between these clones. Further research is required to quantitatively determine mDP, and to identify and quantify individual polyphenols. In conclusion, these insights into the variability of polyphenol composition among genetically diverse cacao will help to inform targeted selection of cacao clones for future studies investigating the impact of cacao consumption on human health.Support or Funding InformationFunding was provided, in part, by the Virginia Agricultural Experiment Station and the Hatch Program of the National Institute of Food and Agriculture (NIFA), U.S. Department of Agriculture