Soy Flour, a Support for Freeze Drying of Acetobacter Pasteurianus Starter for Cocoa Fermentation in Côte d’Ivoire

Abstract

Starters are of great economic importance to our society because of their use in various sectors. It is then important to maintain their viability during the manufacturing process and storage. Freeze drying is one method that is commonly used to preserve bacteria. In this study, various flours were compared with two known cryoprotectants, mannitol, and saccharose, for their cryoprotective potential for acetic acid bacteria. A strain of Acetobacter pasteurianus was grown in YEPG broth and centrifuged. The pellet was then collected and mixed with 20% saccharose, 20% mannitol, a combination of 10% mannitol with corn flour, sorghum flour, millet flour, rice flour, soy flour, a combination of 20% saccharose with maize flour, sorghum flour, millet flour, rice four, soy flour. The freeze-dried starters were stored at room temperature (25 °C), and viability was checked weekly after freeze drying for a storage period of 5 weeks. The results show that sorghum flour, soy flour, and maize flour had survival rates in the order of 73%–78% when used alone. Soy flour alone helped maintain the viability of the strain above 50% during storage for 4 weeks. Soy flour could be used as new potential support for the freeze-drying of Acetobacter pasteurianus. This could help solve one of the many problems in the cocoa culture.