Effect of essential oils on the antibacterial activity and technological properties of dark chocolate

Salmonella outbreaks associated with chocolate consumption are periodically reported. To address this issue, essential oils (EOs) have been proposed to be effective against foodborne pathogens. In addition, EOs constituents appear to modify the lipid phase of the product, leading to an improvement in quality. This study aimed to investigate the antimicrobial potential of EOs from Thymus vulgaris EO (TvEO) and the combination of T. vulgaris and Cymbopogon citratus EO (TvCcEO) in dark chocolate against S. Typhimurium ATCC 14028, as well as their influence on the technological properties during storage. The findings indicate that the EOs had no significant impact on the reduction of the target microorganism. Furthermore, the polymorphic transition from unstable crystals to the most stable form was detected in the chocolate control sample and chocolate with TvEO from 21 days of storage, while the transition in chocolate with TvCcEO was detected from 30 days of storage. Moreover, the addition of EOs reduced the chocolate's tensile strength and retarded the development of fat bloom from 62 days of storage. Therefore, these findings could prove valuable for future research investigating the potential of EOs in chocolate with the aim of delaying fat bloom development or inhibiting microbial growth.