Crystallization of lactose from Carbopol gels

Purpose. To crystallize lactose under static conditions with a view to prep aring crystals of well-defined morphology. Methods. alpha-lactase monohydrate was crystallized from neutralized Carbop ol 934 gels. When the majority of crystals had grown to maturity, the gels were acidified using diluted hydrochloric acid and the crystals were harves ted by filtration or centrifugation and washed with ethanol-water mixtures. Results. Crystals prepared from the gel had a consistently narrower size di stribution than control crystals, prepared from solution under constant sti rring. If crystallization was effected in the gel without sedimentation of the crystals, then the resultant crystals had smooth surfaces without visua lly detectable surface roughness or asperities viewed by optical microscopy . The crystals from Carbopol gels also exhibited the uniform shape of an el ongated tomahawk regardless of the crystallization conditions, in contrast to crystallization under constant stirring, where the crystal shape of lact ose changed with crystallization conditions especially as a function of the initial concentration of lactose. All batches of lactose crystals prepared from Carbopol gels existed as ol-lactose monohydrate, which showed better flowability than the controls of a similar particle size. Conclusions. Crystallization from Carbopol gel produces lactose crystals of uniform size, regular shape, smooth surface, and improved flowability.