The influence of the amorphisation technique on the physico-chemical properties of amorphous lactulose has been investigated. Four different amorphisation techniques have been used: quenching of the melt, milling, spray-drying and freeze-drying, and amorphous samples have been analysed by DSC, NMR, and powder X-ray diffraction. Special attention has been paid to the tautomeric composition and to the glass transition of amorphised materials. It has been found that the tautomeric composition of the starting physical state (crystal, liquid or solution) is preserved during the amorphisation process and has a strong repercussion on the glass transition of the material. The correlation between these two properties as well as the plasticizing effect of the different tautomers have been clarified by molecular dynamic simulations.