Microencapsulation of Gram-Negative Bacteria by Spray Drying

This paper presents an experimental study on preparation of gram-negative bacteria microcapsules by spray drying. Effects of operating conditions on the bacteria survival rate were examined by single factor analysis. Through orthogonal experiment, appropriate conditions were determined as 160°C of the inlet air temperature, 12.5 ml/min of the feed flow rate, 1:9 of the ratio of gum arabic to maltodextrin and 50 ml for fluid nutrient medium with the bacteria. The bacteria survival rate reaches 84.57 %. Examination of storage performance shows that quantity of the viable gram-negative bacteria was increased by 148 % after preserving in plastic film bag for 6 months under ambient temperature from 18°C to 30°C, viability of the bacteria were improved compared to those inoculated from laboratory.