Hydrolysis of Galactosylsucrose (lactosucrose) and the Mechanism of Monosaccharide Release by Small Intestinal Enzymes in Human and Rat
The health benefits of oligosaccharides should be accurately offered to the consumer based
on scientific evidence. In particular, the prebiotic effect of nondigestible oligosaccharide is concerned
with the digestibility and fermentability in the gastrointestinal tract. Since galactosylsucrose is resistant
to the digestion in the gastrointestinal tract, it is widely used as a prebiotic. But, it is still unknown
whether it is partially hydrolyzed by small intestinal enzymes. This is the first report that galactosylsucrose
is slowly hydrolyzed by human small intestinal enzymes. The present study investigated the hydrolysis of galactosylsucrose
using human and rat small intestinal enzymes. Galactosylsucrose was slowly hydrolyzed by small intestinal enzymes
from both humans and rats, although the hydrolyzing activity was lower than that for lactose. Galactose, which is
bonded via a β-4, 1 linkage to the glucose residue of sucrose, was the first moiety to be released from galactosylsucrose;
this increased linearly during the incubation. Glucose and fructose produced from sucrose (which is the hydrolyzed residue
of galactosylsucrose) also increased linearly after a delay during the early period of incubation. These results suggest
that initially lactase attacks the lactose unit of galactosylsucrose, and sucrase then hydrolyzes the resulting sucrose unit.
Thus, hydrolysis of galactosylsucrose starts from the β-4,1-linkage between galactose and glucose at the non-reducing
Keywords: Galactosylsucrose, hydrolysis, lactosucrose, monosaccharide, human small intestinal enzymes.
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