Production and physiological action of the disaccharide lactulose

The disaccharide lactulose is an artificial sugar with a significant impact on human digestion. It can be generated by either alkaline isomerization of lactose via the Lobry de Bruyn – Alberda van Ekenstein rearrangement or by enzyme-catalyzed synthesis. Based on the first reaction, different process schemes for the preparation of lactulose have been developed. Maximum yield of lactulose relative to initial lactose concentration Ylactu/lacto appears to be restricted to 30%, but the presence of complexing agents and further down streaming processes lift Ylactu/lacto up to 88%. The enzymatic synthesis of lactulose can be carried out using different pathways with the transgalactosylation reaction being the most promising. The dose-dependent effects of lactulose include the enhancement of probiotic intestinal flora as well as an increased colonic motility. The physiological action of lactulose has been focussed by clinical trials for over five decades, leading to its application as pharmaceutical as well as a prebiotic food ingredient.