Sonocrystallization: effect on lactose recovery and crystal habit

Sonocrystallization is the use of power ultrasound to control the crystallization process, commonly used during the nucleation phase of crystallization. However, in the present study a different approach has been tried, in which the whole process of lactose crystallization from model reconstituted lactose solutions was completed rapidly with the aid of ultrasound, in the presence of 'ethanol' as an anti-solvent, at temperature of 30+/-2 degrees C (ambient temperature). The lactose recovery and crystal properties from sonicated samples were compared with non-sonicated samples. For optimization of sonocrystallization process for rapid lactose recovery, variations in the time of sonication, lactose concentration, protein concentration and pH were tried. A lactose recovery of 91.48% was obtained in 5 min of sonication time, from a reconstituted lactose solution (17.5% w/v, pH 4.2) as against 14.63% under only stirring. Lactose recovery decreased with lowering of pH from 4.2 to 2.8. The protein showed maximum influence on lactose recovery even at concentration of 0.2% w/v. A rapid process of crystallization gave a better uniformity in crystal size distribution of lactose samples.