Study On The Key Technology Of Fructooligosaccharides From Inulin

Fructooligosaccharides (FOS) is a functional food ingredient. Except used as dietary fiber, FOS can improve intestinal function, reduce blood fat, promote absorption of calcium, iron and other mineral, and widely used in food and healthy food industries. The main composition of Jerusalem artichoke is inulin. Inulin is a linear polymer of D-fructose containing a terminal D-glucose. Inulin is a mixture of fructan with different molecular weight and the degree of polymerization (DP) varies from 2 to 60. Frctan whose DP is 3~10 is called FOS. During the production of FOS from inulin, there are some key problems to be resolved, including deslating of inulin extract, purification of inulin extract and preparation of FOS. These key technique problems during FOS production were investigated in this work.Demineralization of inulin extract with ion exchange resins was investigated. According to the ability of demineralizaton, 6 ion exchange resins were selected from 16 different types of resins. They were divided into 4 groups and were assembled in the order of anionâ†'cationâ†'anion. The results of demineralizaton experiments showed that group A (D202â†'D001-Fâ†'D315) was the best resin group. After demineralizing inulin extract by the resins of group A, electric conductivity of inulin extract decreased from 5050μs/cm to 240μs/cm, which meets the quality demand of inulin product (ash content is less than 0.1 %), and the disposal volume was 4 times of column volume.Chromatography and fermentation methods were used to purify inulin extract in this work.Using static and dynamic screening, a Ca type resin with the best separation ability was selected from 7 resins. The influences of temperature, resin volume, feed volume and washing rate on the separation of sugars in inulin extract were investigated. The optimal separation conditions were: column temperature 70°C, resin volume 200 mL, feed volume 2 mL, washing rate 1 mL/min, the recovery rate was 84.71 %. However, the productivity was lower and needed to be improved.Using inulin extract as culture medium, purification of inulin extract was successfully carried out by inoculating Yanshan yeast and fermenting. The optimal fermentation conditions were: 8.0% inulin extract + 10 mmoL/L Na2SO3, inoculation volume 1.5 %, temperature 28°C, initial pH5.5, 200 r/min, and fermentation time 4 h. The removal rate of sugars was 81.84 %, which met the demand of inulin production. Only was the inulin concentration 30 % did the sediment of inulin in higher DP take place, and the volume of sediment increased when the inulin concentration increased. Lower temperature was helpful to precipitation of fructan with higher DP. Longer precipitation time was favourable to the separation between long-chain inulin and short-chain inulin. The preparation techology of FOS from inulin was as follows: 35 % inulin extraxt was frozen at -18°C, and then melted and put at 0°C for72 h. Through centrifugation, the supernatant obtain was FOS.