Flavan-3-ols Monomer and Oligomer, and Flavor Profiles of Chocolates Produced from Fermented Cocoa Beans under Different Roasting Degree in Taiwan

Abstract

Taiwan cocoa beans were fermented in a wooden box by natural occurring microorganisms for seven days. Six types of chocolate were manufactured from the fermented cocoa beans under different roasting degree. The fermentation parameters including the count of microorganisms, fermenting mass temperature, pH value of the pulp and cotyledons of cocoa bean along with the fermentation time were determined. Furthermore, the flavan-3-ols monomer and oligomer (FMO) of chocolates were determined by normal phase HPLC and the volatile aroma compounds of the six types of chocolate were analyzed by electronic nose to identify the important flavors and odors. Primary component analysis (PCA) was performed to distinguish the flavor profiles among the chocolates. The sensory assessment was conducted to evaluate the organoleptic properties of the six types of chocolate and their overall acceptability. The results showed that the total amount of FMO and proanthocyanidins in the chocolate both decrease with the intensity of the roasting degree of cocoa beans. Twenty-three important volatile aroma compounds were identified by electronic nose analysis. Differences in the amount of each compound were determined in the investigated chocolate and these are expected to cause sensory differences among the six types of chocolate. As a result, chocolates produced from beans under medium roasting condition (130°C and 25min) rated the highest score of overall acceptability among the chocolates. It was significantly higher than those of chocolate produced from light roasting beans. On the other hand, chocolate produced from cocoa bean under light roasting degree was retained more content of the bioactive compounds and could be a potent candidate of health functional food. PCA was successful to discriminate the flavor profiles of the six types of chocolate produced from beans under different roasting degree and could be used as a tool to recognize the origin of chocolate product. These results of this study could provide an important approach for producing chocolate products with desired flavor properties and bioactive compounds that have positive benefits for human health.