Study On Processing Technology Of Highly Purified Galacto-oligosaccharides

Galacto-oligosaccharide(GOS) is a kind of natural functional oligosaccharides.In nature, GOS usually exits in breast milk of animal and human, especially contents inthe breast milk of hunman is the most. The establishment of bifidobacterium in baby’sbody largrly depends on the GOS in breast milk. Because of its unique inhibition tointestinal putrefying bacteria, the improvation of lipoprotein metabolism, the reducingof cholesterol, the promotaion to mineral absorption, and its physiological function, ithas broad application prospects. However, now GOS made by enzymictransgalactosylation reactions has litmited application scope because of its poor purity.In this study, the HP GOS was produced by fermentation, and the main processesare as below: high concentration of lactose solution fermentation by Aspeigillus oryzae,ceramic membrane ultrafiltration, nanofiltration, chromatography, concentrated byevaporation and drying. Fermentation conditions were optimized, and the optimizationparameters are as below: fermentation temperature, fermentation time, fermentation pHlactose concentration, the quantity of β-galactosidase, and the ventilation. The optimumfermentation conditions were determined: lactose contration was40%, inoculumvolume was10%(m/V), fermentation pH was5.0, fermentation temperature was30°C,fermentation time was35h, the quantity of β-galactosidase was20mL/100mL, theventilation was the0.4m3/h, the stirring speed was250rpm and aeration rate was0.4m3/h.The separation and concentration process was carried on by cellulose acetatenanofiltration membranes(CA), a comparative analysis of the single factor wasimplemented to nanofiltration membrane operating pressure and feed concentration, andthe optimum separation conditions were determined: nanofiltration membrane operatingpressure was2.0MPa and the feed concentration was20%, the temperature was25-35℃, and the result showed that lactose, galactose and glucose were separated effectively,and the purification of GOS can be more than80%. The separation efficiency can beimproved by new four sequencial moving bed, and the purification of GOS can be90%.The purification of80%and90%of GOS product was got by using the processesabove, and the whole technology has many advantages, such as mild reaction conditions,easy to industrial production, high yield, short cycle, high efficiency and economy.