Microencapsulation of Gram-Negative Bacteria by Spray Drying

This paper presents an experimental study on the 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 degrees C of the inlet air temperature, 12.5 ml/min of the feed flow rate, 1: 9 of the ratio between gum arabic and maltodextrin, and 50 ml of fluid nutrient medium with the bacteria. The bacteria survival rate reaches 84.57% associated with above conditions. Examination of storage performance shows that after preserving in plastic film bag for 6 months under ambient temperature from 18 degrees C to 30 degrees C, quantity of the viable gram-negative bacteria was increased by 148%, which was significantly improved compared to those inoculated from laboratory.