Microorganism preservation by convective air-drying—A review

At present, microorganisms are mainly preserved by freeze-drying. There is, however, lack of studies conducted on various cheaper yet promising convective air-drying alternatives. Convective air-drying has been proven to produce dried culture with comparable cell survival and final moisture content to that of freeze-drying. This paper aims to draw an understanding to application and suitability of convective air-drying which includes spray, oven, heat pump, fluidized bed, conveyor, and rotary drying to preserve microorganisms. The paper concludes that drying near ambient temperature and the addition of dehydration protectants are important to obtain satisfactory drying quality.