| The research on soybean oligosaccharides is a popular subject in nutrition nowadays because of its multiple bioactivities and better performance of processing. Therefore, the demand of consumer is also increasing every year. In the study, the soy whey waste water is utilized to separate soybean oligosaccharides for purpose of reducing soybean whey emissions and environmental pollution; increase the added value, while improving a theoretical reference for the extraction of soybean oligosaccharides production process. And the pretreatment of soybean whey oligosaccharides, separation and purification, physical and chemical properties, and membrane cleaning are researched. The research results as follows:1.Application of coagulant to pretreatment of extracting the soybean oligosaccharides by ultr afiltration. It were investigated that effects of pretreatment ways of Chitosan flocculation, lime flocculation, transglutaminase polymerization to soy whey wastewater on the seperation of soy oligosaccharide using ultrafiltration and its pretreatment process optimization in this paper. The results showed that the optimum conditions of chitosan flocculation were:addition amount of magnetic chitosan microsphere0.8g/L, contacting time60min, temperature30℃, and pH5.5.The protein removal rate was61.21%, whereas hardly has any significant effect on total sugar of soybean,the loss rate was3%. Color value was reduced by24.5%, and the transmissivity was increased by99.4%. After pretreatment, the attenuation of the flux was reduced from6.31L/m2h to2.5L/m2h, Membrane fouling was declinded effectively.2.Separation performance of soybean oligosaccharides from soy whey were investigated by regenerated cellulose Ultrafiltration membrane (UF) membrane with a molecular weight cut-offs (MWCO) of5000on retention efficiency of soy whey protein and penetration efficiency of total sugar, degree of membrane fouling and penetration flux. Firstly, the optimal parameters obtained by the single factor experiments were that pretreated soy whey filtered at concentration ratio of4:1, TMP40-60KPa, pH6.5～7.5and diafiltration times0～2。The response surface design was employed to optimize the process parameters. The results showed that the pressure55KPa, pH7.30, once diluted using batch operation of cross-flow ultrafiltration.The retention efficiency of Soy whey protein and penetration efficiency of total sugar was95.87%and82.14%respectively. The content of protein and color value was reduced by93.54%and62.42%respectively. The transmissivity of improved syrup was increased from68.4%to90.1%. By HPLC analysis, the content of sucrose, raffinose, stachyose of the soy oligosaccharides was1.77mg/ml、0.57mg/ml、4.89mg/ml respectively. 3. The water dynamic flushing and chemical cleaning of the ultrafiltration membrane were systematically researched to cross-flow ultrafiltration process. The results showed that the dynamic flushing required to be operated with surface flushing under the condition of50KPa at35℃for10min, while the flux recovery rate was32%. The chemical cleaning was operated subsequently. It seemed that0.2mol/L NaOH with20min of cleaning time was a better selection for cleaning UF membrane fouled by soybean whey wastewater as that its permeate flux recovery rate could reach90%and more. Higher concentration of cleaning agents might change the characteristics of membrane. Alkali soak was indispensable after dynamic washed to increase the flux recovery; the longer the time of membrane fouling, the soaking time should be increased accordingly.4. Application of ion exchange resin was investigated to enrichment of soybean oligosaccharides. The results showed that the optimal desalination and decoloration conditions was to purify4BV soybean oligosaccharides with001x7strong acid cation exchange resin and D301-T macroporous weak basic anion exchange resin series connection, volume ratio of cation resin to anion resin1:1, flow rate2.4BV/h, room temperature. The desalination rate and decoloration rate of soybean oligosaccharides were81%and94%respectively under the condition. The retention rate of total sugar was more than91%. By HPLC analysis, the soybean oligosaccharides content increased by13.43%compared with UF sample. The purified soybean oligosaccharides and the functional oligosaccharides were51.64%and47.96%accounting for total solids respectively, the content of raffinose, stachyose was4.74%、33.22%respectively.5. The quality analysis and physicochemical properties of soybean oligosaccharides were researched. The preparated soybean oligosaccharides were white powder, and the indicators of GB/T22491-2008were reached. The viscosity of soybean oligosaccharides decreased with increasing temperature, and viscosity of the greater concentration decreased significantly. The solubility was less under alkaline conditions than that of the same concentration under acidic and neutral conditions. The browning degree was lower under acidic and neutral conditions, and was higher under alkaline conditions. |
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