| Curdlan is an extra-polysaccharide produced by Alcaligenes faecalis. It has application potential in food industry for its peculiar thermo-gelling property. In this work, continuous fed-batch fermentation of curdlan by Alcaligenes faecalis WX-C12 was investigated. Preliminary study of curdlan vacuum drying technology was carried out. In addition, spray drying technology of curdlan was firstly investigated. This work was available for commercialization of curdlan.Based on the previous work, fed-batch fermentation process of curdlan was investigated. An optimal fermentation production process for curdlan The pH controlled at 7.0 by ammonia water with initial NH4Cl concentration at 0.5g/L in the medium was in favor of cell growth. While at the stage of curdlan formation, glucose controlled at 15g/L ~20g/L by the strategy of continuous fed-batch with pH controlled at 5.6 by NaOH were better for curdlan production. The highest yield of curdlan 72g/L with a conversion rate of 78.8% was achieved with the biomass of 11.9g/L, showing an increase of 157% as compared with batch fermentation. However, the yield of curdlan dropped down when the biomass continually increased. A mathematical model was adopted to model and predict the process of curdlan production.A method of vacuum drying was used for curdlan drying and a reasonable drying technology parameter was determined. The experiment of single parameter for vacuum drying was conducted under different conditions. The relationship between parameters (drying temperature, vacuum, material thickness) and vacuum drying ratio, moisture content were determined. Through analysis of orthogonal experiment, an optimum conditions were obtained: 50℃, vacuum of 0.07MPa and material thickness of 2mm.Spray drying of curdlan was carried out in a QZ-5 high-speed centrifugal spray dryer. The optimum processing parameters was obtained according to curdlan quality: the inlet curdlan of 1.5 %, the inlet flowing rate of 6 mL/min and the inlet temperature of 200℃.
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