Particularities and challenges in the crystallization of nonsucrose sugars

Nonsucrose sugars include sugar substitutes (such as erythritol, maltitol, mannitol or xylitol), also known as sugar alcohols or polyols, and so-called rare sugars (such as allulose, arabinose or tagatose) which are also made available for industrial use through the development of new synthesis processes and methods. There is a growing demand for these products in crystalline form. Besides being used as sweeteners in the food industry, they are now also used in pharmaceutical and cosmetic products, and as a platform chemical in green chemistry. Because of their specific chemical structures, the nonsucrose sugars have different chemical and physical properties. The solubility, crystal growth and form of the individual sugars and sugar substitutes therefore also differ. In particular, they differ from the known sucrose properties and data. This requires different approaches to crystallization and to all other applied process steps. Thanks to specific analytical methods, the characteristics of various sugars can be assessed, variants for technical processes recommended, and apparatus and equipment designed and adapted to the specific features of the sugars. Based on the findings, an initial technical concept for a crystallization plant can be developed.