ABSTRACT

This study investigated the maintenance and assessment of microbial cell viability in selected carriers (cryoprotectants). Drinking yogurt and pap samples were collected for the laboratory isolation of lactic acid bacteria. Identification of the suspected colonies and probiotic characterization tests were carried out. The colonies were found to be lactic acid bacteria and they showed probiotic potentials. In the maintenance of the viability of this lactic acid bacteria cell, Freeze drying technique was selected and a cryoprotective carrier, combination of skim milk and sucrose was incorporated in the culture medium prior to freeze drying. A standard plate count was carried out on the culture before and after freeze drying in cryoprotectants. A plate count was also carried out on a control culture for freeze drying without cryoprotectants. Result showed that there was improvement of viability of the cells in culture freeze dried with cryoprotectants with increase in growth from 0.72×105 to 0.74×105 CFU after 7 days of storage at room temperature. While viability of cells freeze dried without cryoprotectants was partly contained but cells suffered from sub lethal injury during freezing. This study thus concludes that the incorporation of a cryoprotectants medium in microbial cell culture while freeze drying is very effective for the maintenance of the cell viability.