Abstract
Ochratoxin A (OTA) is a mycotoxin causing serious adverse human and animals health effects while free fatty acids (FFA) are carboxilic acids from hydrolysis of cocoa butter due to the lipolytic filamentous fungi activity. During the primary post-harvest processing notably the storage, the quality of dry fermented cocoa beans is currently altered due to the elevated production of both FFA and OTA ascribed to the growth of both extracellular lipase and mycotoxins producing filamentous fungi species regarding. This study investigated the ability of two Bacillus species to reduce both the OTA and FFA production in dry fermented cocoa beans by inhibiting the growth of producing filamentous fungi strains. Cocoa beans were extracted from cocoa pods of the cultivar ripe pods Amelonado, Ivorian first generation of hybrids (Forastero) and open pollinated progenies harvested at farmer plantations in October 2020. Fourteen Bacillus species isolated from both fermented African locust seeds (9) and cocoa beans (5) were identified using molecular tools. Antifungal activity of these Bacillus species against the growth of OTA producing Aspergillus carbonarius strain was highlighted. Suspensions of each antifungal Bacillus strain cells adjusted to 108 CFU.mL-1 were individually inoculated to 80 kg of fresh cocoa beans extracted from cocoa pods stored during 0, 4, 7 and 10 days. Cocoa beans fermentation was processed with two turnings at 48 and 96 hours of the process for 6 days. Fermented cocoa beans were sun-dried until to 7-8% moisture. FFA and OTA of cocoa beans were quantified by Association of Official Analytical Chemists (AOAC) and high-performance liquid chromatography with fluorescence detection (HPLC-FD) methods respectively. Main results indicated that Bacillus halotolerans and Bacillus thuringiensis strain ATCC 10792 were greater antifungic than Bacillus paramycoides, Bacillus subtilis Subsp subtilis, Bacillus subtilis, Bacillus albus, Bacillus thuringiensis strain IAM 12077. Their inoculation to cocoa beans during spontaneously fermentation totally removed OTA and strongly reduced FFA production. The results of this study indicate that various Bacillus species could be applied as promising biological agents to improve the microbiological quality, to remove OTA from dry fermented cocoa beans and to reduce their FFA content without influencing the organoleptic attributes of the chocolate produced thereof.