Galactosyl-oligosaccharide formation during lactose hydrolysis: a review

Enzymatic hydrolysis of lactose is accompanied by galactosyl transfer to other sugars, thereby producing oligosaccharides. These are hydrolyzed slowly, both in vitro and in vivo. They can be thought of as low molecular weight, non-viscous, water-soluble, dietary fibre. They are considered to be physiologically functional foods which promote the growth of bifidobacteria in the colon and a wide variety of health benefits has been claimed in connection with this effect. This article reviews the mechanism of oligosaccharide formation, and then discusses the amount and nature of the products as well as the factors which influence them. The appearance and disappearance of oligosaccharides is explored through consideration of the kinetics of tranferase activity. The consequences of oligosaccharide formation for dairy processing, food analysis, nutrition and health are then briefly discussed.