Oriented intergrowths and colouring of sucrose crystals effected by surface adsorption processes

Oriented intergrowths and colouring of sucrose crystals were investigated i n solutions containing glucose, fructose, raffinose, brown sugar and black tea extracts as additives and compared to their growth behaviour in pure so lutions, It was found that in laboratory experiments oriented intergrowths occur mor e often than exact twins, This is contrary to observations of industrial pr oducts. In pure solutions and in the presence of the additives, with the ex ception of raffinose, intergrown crystals are found on the {1-10} faces and on a part of the neighbouring faces; the intergrowths are connected to the host crystal by the negative poles of their b-axes, With raffinose, interg rowths occur on the {110} faces and on a part of the adjacent faces. These intergrowths are connected to the host crystal by the positive poles of the ir b-axes, Experiments have shown that larger crystallites grow together with the host crystal, Exact twins with [001] as the twin axis are found only near the e dges between the {1-10} and {110} faces. The twin type mentioned in literat ure with {100} as the composition plane seems to be a transition form of th e two types conditioned by growth. The mechanism for these growth effects c an be attributed to surface adsorption processes caused by different interf ace interactions.