Emphasis on Techno-functional Properties of Bacillus Strains Involved in Ivorian Cocoa Fermentation towards their Use as Potential Starter

Abstract

Aims: To investigate in Bacillus strains some functional properties potentially interesting for cocoa fermentation processing Place and Duration of Study: Laboratory of Biotechnology, UFR Biosciences, University Félix Houphouet-Boigny (Côte d’Ivoire), between May 2014 and March 2015. Methodology: Spontaneous heaps fermentation were conducted in three cocoa producing regions. Bacilluswere isolated from cocoa fermentation using plate agar on nutrient medium and analyzed for pectinolytic enzymes production, citric acid breakdown, acidification and thermotolerance: these properties are known as essential for cocoa fermentation. Results: A total of 600 Bacillus strains were isolated and 42.50% of them produced pectinolytic activity with different levels of enzymes production. The production of these enzymes is influenced by sugars content and ethanol beyond 2%, while the influence of acid was sharper with 0.15% as limit of tolerance. A large proportion of Bacillus population (67.16%) exhibited acidifying capacity, this property was accompanied by gas production in some strains. The total acidity yield ranged from 30 to 300 mg/L and strains presenting gas production tend to produce more acid. Additionally, more than 75% of acidifying strains presented the ability to breakdown citric acid. Moreover, all the strains exhibited a strong thermotolerance at 45ºC with a level of bacterial growth round 80% of that reached at 35ºC, the optimal growth temperature. The distribution of these properties in the Bacillus population was not uniform in the different regions. Conclusion: This study indicates that Bacillus strains involved in Ivorian cocoa fermentation possess some properties such as ability to produce pectinolytic enzymes, capacity to breakdown citric acid and strong thermotolerance at 45ºC, essential for a well-fermented cocoa. These strains may play a more important role in cocoa fermentation, than it is believed at date. Taken together, these results show that Bacillusstudied should be potential candidate as starter for cocoa fermentation control.