Cocoa By-products As An Alternative to Expensive Cryoprotectants for Freeze-drying of <i>Lactobacillus plantarum</i>

Lactobacillus plantarum is a lactic acid bacterium involved in a number of fermentations, including cocoa. This strain is subject to genetic modification if poorly preserved, hence the importance of lyophilisation. However, synthetic cryoprotectants are used to protect the strain during freeze-drying. However, these cryoprotectants are expensive and increase the cost of freeze-drying. The aim of this work is to develop a cheaper freeze-drying medium for Lactobacillus plantarum from cocoa by-products. To achieve this, the Lactobacillus plantarum strain was cultured, centrifuged and the resulting pellet was recovered. Cocoa pulp and cocoa pod powder were prepared and autoclaved at 121°C for 15 minutes each, then added to the pellet alone or in combination. A sucrose control was made samples were frozen and lyophilised. Survival rate and acid production were assessed after freeze-drying. The highest viability rate after freeze-drying was recorded with cocoa bean liquor (82.88 ± 0.37) compared to 76.83 ± 0.21 for the control. The acidity of the cocoa bean liquor after freeze-drying was identical to that of the control. Cocoa bean liquor could be used as an alternative to cryoprotectants, which are too expensive for freeze-drying Lactobacillus plantarum.