Fructo-oligosaccharides and sucrose crystal growth morphology – I. Experimental growth habits

Because in both cane and beet molasses fructo-oligosaccharides are normally present, the effect of such compounds on sucrose crystal growth morphology has been tested. Sucrose crystals nucleated in the presence of the above mentioned compounds showed an unusual triangular shape as a consequence of the abnormal development of the sizes of o-{1–11}, q-{0–11}, w-{1–1–1} forms and the considerable decrease of that of p-{1–10} form, up to the disappearance of the [001] edge between its faces. If the crystals grew on, even the o’-{111}, q’-{011}, w’-{11–1} forms appeared and steadily increased in size on the right pole, so decreasing the size of p’-{100} form. Consequently, even the right [001] edge disappeared, so that the final growth habit of the crystals exhibited an unusual “rhombic” shape. Growth morphologies of sucrose twins, grown under the same experimental conditions, were in agreement with those observed for single crystals. Finally, the ratios between the face kinetics, which have to be considered as inducing the observed habits, are qualitatively discussed.