Enzymatic production of galacto-oligosaccharides

Galacto-oligosaccharides (GOSs) are properly considered as a prebiotic based on scientific evidence about their physiological effects, having some unique properties among prebiotics that allow them to be used as supplement in formulas for infants where they mimic the physiological effect of human milk oligosaccharides, which are key components in breast milk. GOSs are produced by enzymatic transgalactosylation of lactose with β-galactosidases, so their production technology is tightly connected to the field of enzyme biocatalysis. The chapter thoroughly reviews all aspects of GOS production with whole cells and isolated enzymes, both free in solution and immobilized. Special attention is given to downstream processing of the raw GOS produced to cope with the quality standards imposed by their use as special food components. Cost of downstream operations is a major issue, so advances in GOS purification by different strategies are analyzed. Finally, current applications and perspectives of GOS within the prebiotic sector are reviewed and appraised. Competition with other well-established prebiotics (inulin and fructo-oligosaccharides) and potential prebiotic newcomers is envisaged, so the unique properties of lactose in terms of their physiological effect and functional properties are on the basis of GOS consolidation in an increasingly competitive market.