Lactose Hydrolysis and Enzyme Immobilisation
Galacto-oligosaccharides (GOS) have several health benefits and can be used as prebiotics
Galacto-oligosaccharides (GOS) have several health benefits and can be used as prebiotics. In the colon, as GOS are not digested in the upper part of the gastro-intestinal track, GOS stimulate the growth of beneficial (bifido)bacteria and the growth of harmful bacteria is inhibited. Besides, GOS inhibit the development of colon cancer.
Because GOS are naturally present in milk, GOS are also added to infant nutrition to resemble human breast milk as close as possible. (Boon 2000; Bruins 2003; Tuohy 2009)
GOS consist of a mixture of oligosaccharides with degree of polymerization (DP) 1 up to DP 10 with a varying amount of galactose molecules attached to a lactose molecule.
GOS are produced by conversion of lactose by β-galactosidases (EC 18.104.22.168). This enzyme possesses two kinds of activity: hydrolytic activity, which converts lactose into glucose and galactose, and transgalactosylic activity, which converts lactose into galacto-oligosaccharides. (Boon 2000; Bruins 2003)
Aim of the research
The final aim of this project is to optimize GOS production by constructing a process that results in a higher oligosaccharide yield and a lower lactose content.
The enzyme preparation used is a β-galactosidase from Bacillus circulans. The focus will be at determination of the kinetics of the enzyme preparation. This will be performed in microreactors. Next, a kinetic model will be constructed, which can be used to make predictions on oligosaccharide yield.
Subsequent process optimization might include other reactor concepts, increase of the substrate concentration, and change of pH and temperature.
- Boon, F. (2000). "Enzymatic synthesis of oligosaccharides." Process Engineering. Wageningen University. PhD thesis. Abstract
- Bruins, M. E. (2003). "Oligosaccharide production with thermophilic enzymes." Process Engineering. Wageningen University. PhD thesis. Abstract ; Full Text
- Tuohy, K. M. (2009). "Commentary on "Prebiotics, immune function, infection and inflammation: a review of the evidence"" British Journal of Nutrition 101(05): 631-632. Abstract ; Full Text