Survival of Brevibacterium linens (ATCC 9174) after spray drying, freeze drying, or freezing

The objectives of this work were to: (1) contrast spray drying, freeze drying and freezing for large-scale preservation of B. linens, (2) determine the thermal resistance curves, and (3) measure the storage stability. When B. linens was freeze-dried and frozen in feed suspensions containing 3% (w/v) cell paste and 25% (w/w) total solids, survival was 100%. During spray drying, lethal thermal injury was the main cause of loss of viability. Accordingly, by extrapolation, 100% viability would be possible at an outlet-air temperature of 57 degrees C. Spray-dried and freeze-dried cells were stable during storage at 4 degrees C in the absence of oxygen and moisture.