Study On Fermentation Of Kefiran

Exopolysacchaeid(EPS) of Lactobacillus has become one of focused researches recently. Kefiran is one kind of Lactobacillus EPSs, it has many important physiological functions, and is widely used in many fields, i.e. clinical medicine, food industry, chemical industry and so onIn this paper, the fermention conditions of Lactobacillus kefiranofaciens to produce Kefiran.were studied, Kefiran was separated and purified The composition, structure and characteristics of Kefiran were investigated.The main contents of this dissertation were as follows:1. The initial fermented characteristics of L.kefiranofaciens were studied. The inoculation ratio, initial seed age and the fermentation time were confirmed. The morphologe of the cell was observed in the process of the fermentation.2. The fermentation conditions were optimized by single factor experiment and orthogonal design. The results show that the temperature of culture and pH to be controlled during the fermentation process made a remarkable effect on growth of cell and production of EPS. When adopted CaCO3 to control pH and cultured at constant temperature 25℃, the yield of Kefiran could reach to 1.96g/L3. The composition of culture medium was optimized and the yield of EPS could arrive at 2.5g/L when malt juice and domestic yeast powder as the industrial raw materials were used during the fermentation process. The Kefiran yield further raised to 2.6g/L after dosage of mineral and trace element were optimized by Response Surface Analysis.4. Several methods to remove of protein from crude Kefiran were studied. The results showed that the alcalase treatement combined with Sevage reagent method was better.5. HPGFC, HPLC and IR were used to research on properties of Kefiran. Structures and properties of two kind of Kefiran produced from two different culture mediums (MRSL and malt juice) were contrasted, and the result indicated that if ingredients of culture mediums were different, properties and configuration of polysaccharides obtained after fermentation also presented quite difference. Rheology property of Kefiran was investigated and [η] was 73.86[100mL/g].