The Experimental Investigation On Spray Drying Of Fructooligosaccharides

As a new-style sanitarian foodstuff, fructooligosaccharides has much outsta –nding property, it is liked by the majority of consumers. Compared with liquid fructooligosaccharides, solid fructooligosaccharides can overcome the inconvenience of selling and transportation that liquid fructooligosaccharides brings, and promote the use of fructooligosacharides in daily life. Melting point of fructooligosaccharides is lower, moisture absorption is very strong,so there are many difficulties during spray drying of fructooligosaccharides. Accordingly, making researches on spray drying of fructooligosaccharides has economic and scientific value. Comparing the economic cost of spray drying with that of vacuum freeze drying,production cost of spray drying is lower. By experiments, the technical project of spray drying of fructooligosaccharides is ascertained, the parameters of drying are optimized, the range of the parameters is obtained. Through X-diffraction, it is confirmed that the ingredient of fructooligosaccharides does not change during the process of spray drying. In order to scale up spray dryer of fructooligosaccharides in industry, Water is used as working fluid of atomization in this paper, investigating the spray characteristics about pressure nozzle, measuring the relation between nozzle flow capacity,spray angle,droplet diameter and pressure, the distribution of droplet diameter and radial spray flux of nozzle are also obtained. The experimental results show that pressure and nozzle aperture influence nozzle flux,spray angle,droplet diameter at the same time, droplet diameter mostly is 80～200μm, when P<7.0MPa, the air core of nozzle have little effect on the distribution of radial spray flux. Sticking wall is very serious in the course of spray drying of fructooligosacchari -des, it can be solved by the method using air curtain to cool the wall of the drying tower. Drying tower which is used in the experiment is made as a model, the effect of velocity of cooling air and the width of cirque on temperature field of drying medium in drying tower is analyzed. The results show that when the velocity of cooling air and the width of inlet-cirque are changed, the effects on wall cooling and high temperature region of drying-tower must be considered.