Effect of the Improvement of Cocoa Raw Material Quality by Application of Anti-Fungal Bacillus Strains during Fermentation on the Chocolate Sensory Attributes

This chapter focuses on evaluating the effect of application of anti-fungal Bacillus strains on cocoa beans fermentation. Contamination with filamentous fungi reduces the quality of cocoa beans and poses a health risk for consumers due to the potential accumulation of mycotoxins. This study involved in developing antifungal Bacillus strains culture to enhance the process of cocoa beans.

Seven strains of the genus Bacillus, namely Bacillus mycoides, B. protéolyticus, B. albus, B. subtilis, B. paramycoides, B. toyonensis and B. thuringiensis strain ATCC 10792 were used in this study. The antagonistic bacteria of the genus Bacillus were obtained from spontaneous cocoa beans fermentation.

Solid culture media inoculated with bacterial and fungal isolates were cultivated under aerobic conditions at 30ºC for 5 days. All the strain have strong antifungal activity and the cocoa beans in Cote d'Ivoire were inoculated into 180-kg boxes for fermentation in three time-independent replications, each with a spontaneous control fermentation. This chapter revealed that the B. thuringiensis strain ATCC 10792 did not affected the fermentation process and cocoa bean quality. The anti-fungal in vivo assays revealed that the B. thuringiensis strain ATCC 10792 completely inhibited growth of all fungi on the surface of cocoa beans. The result demonstrated that there are no appreciable variations in the sensory assessment of chocolates forall treatments. B. thuringiensis strain ATCC 10792 did not affect the aroma, texture, or appearance of the chocolate, as evidenced by the excellent sensory quality of the control and chocolates made from the inoculated cocoa beans.

B. thuringiensis strain ATCC 10792 isolated from cocoa beans showed the highest inhibitory activity against Aspergillus carbonarius voucher IHEM 661 and contributed in a significant suppress fungal growth when it was cultured in combination with cocoa beans contaminated by molds. About sensory evaluation of chocolates made from the inoculated cocoa beans with B. thuringiensis strain ATCC 10792 and non-inoculated control, consumers did not report a significant preference for either chocolate (p < 0.5). Due to an acceptable sensory property, it can be concluded that B. thuringiensis strain ATCC 10792 could be successfully used in the production of dark chocolate. This observation allows thinking that B. thuringiensis strain ATCC 10792 cultures should be investigated in further studies for an effective biological control of mycotoxins during the traditional processing of cocoa.