Caking and adhesion free energy of maltitol: Studying of mechanism in adhesion process

Caking is a common phenomenon of maltitol that causes problems of separation, processing and transportation. To study the mechanism of caking, method of capillary rise was used to measure the contact angles between maltitol particles and relevant liquids. Based on the calculation of adhesion free energy of maltitol particles in different liquids by Lifshitz–van der Waals acid-base theory, the relationship between adhesion free energy and the maltitol particles size has been established. It is concluded that the adhesion free energy of maltitol with rinsing liquid plays a key role in caking. When the adhesion free energy is higher than a critical value (about 60 mJ/m2), the repulsion between the particles can avoid caking. In general, the adhesion free energy depends on the rinsing liquid used and maltitol particles size. The adhesion free energy increases with increasing the particles size of maltitol and type of liquids (water, ethyl acetate, formamide, ethylene glycol, ethanol, methanol in sequence). Hence, controlling particles size distribution and screening of rinsing liquid are crucial factors to avoid caking.