Phenomenological study of the synthesis of pure anhydrous β-lactose in alcoholic solution.

Lactose is an important additive because of its food, pharmaceutical, and cosmetic applications. Among lactose polymorphs, anhydrous β-lactose stands out due to its thermodynamic stability. Thus, a simple method to produce the inter-conversion from monohydrate α-lactose to anhydrous β-lactose was investigated employing a methanolic solution and different reaction variables (catalyst type, temperature, and stirring). Pure β-lactose powders were synthesized in short reaction time (2-16 h), with a moderate temperature (reflux: 65 °C), and low concentration (0.014 M) of catalysts (NaOH and KOH). The SEM analysis revealed a change in the morphology from fine needles to tomahawk shape, which is dependent on the content of β-lactose. The products were appropriately characterized using common analytic procedures (XRD, FTIR, and MDSC). In addition, an exhaustive discussion of the obtained results is provided. Finally, it seems to be the first work, where the inter-conversion to pure β-lactose is reported successfully.