Lamine SAMAGACI^1,, Hadja OUATTARA¹, Victoria KADET¹, Syntyche BOGUI², Théodore DJENI², Sébastien NIAMKE¹

Microbial starters are of great economic importance to the food industry and many other sectors. These organisms ensure that food is processed to produce reproducible products of consistent quality. Maintaining their stability and viability during processing and storage is therefore a priority. Of all the methods proposed for their preservation, freeze-drying remains the most suitable for bacteria. In this study, cocoa pod flour and/or pulp was used as a cryoprotectant, in comparison with mannitol, the cryoprotectant that best protects acetic bacteria. Acetobacter pasteurianus strains were grown in YEPG broth and centrifuged. The pellets were then collected and mixed with 20% mannitol, cocoa pulp juice, cocoa pericarp flour, and a combination of cocoa pulp juice and cocoa pericarp flour. The samples were freeze-dried, and the survival rate after freeze-drying and during storage as well as acid production were assessed. The results show that the combination of cocoa pericarp and cocoa pulp juice preserved the strains better during lyophilization and storage (79.24 ± 0.32%) than the control (76.05 ± 0.37%) and the other trials. In addition, the acid production of the strain was better preserved by the combination of cocoa pericarp flour and cocoa pulp juice than in any of the other trials. Cocoa pericarp flour combined with cocoa pulp juice could be used as an alternative cryoprotectant for freeze-drying of Acetobacter pasteurianus. This could enable the valorisation of cocoa residues, such as pod and pulp.

Acetobacter pasteurianus, cocoa pulp, cocoa pericarp, cryoprotectants