Investigation On Enzymic Preparation Of Galactooligosaccharides And It's Application In Milk Powder

Preparation of galactooligosaccharides(GOS) by enzymatic synthesis from high concentration of whey and its application on milk powder as functional ingredients were investigated in this paper.Single factorial experiments were carried out to study the effects of factors on GOS preparation, then optimized the parameters by orthogonal design. The optimized parameters were temperature 50 , reaction time Ih, lactose concentration 30%(w/v), pH4.5, -galactosidase concentration 0.12%. GOS were separated and determined by thin-layer chromatography during the single factor experiments. Thin-layer was made of silica gel with 0.1mol/1 Na2HPO4 and activated at 110 for Ih. The solvent system was butanol:acetone:water=4:5:l. Samples were determined by HPLC during the orthogonal design and GOS content was 23.4% in the end product. The end product was spray dried or mixed with milk and GOS whey powder and GOS milk powder were acquired. The contents of GOS powder milk were protein21.7%, fat!9.7%, saccharide58.6%, and GOS7.5%. In order to evaluate the bifidofactor, functionality of GOS, experiments were carried out in vitro and GOS whey powder and GOS milk powder showed higher bifidobacterium growth activity compared with skimmed milk and commercial functional milk.Kinetic models of GOS production and lactose hydrolysis wereobtained by analysis of experimental data through Matlab data analysis software. As a result, the experiment data fitted well with these models.