Several lactose samples containing various amounts of amorphicity were studied with an isothermal microcalorimetric technique,
which allow to detect the heat and the quantity of water sorption simultaneously. As interaction with vapor is characteristic
of different surfaces, the samples were easy to be discriminated from each other by studying sorption behavior. With the crystalline
lactose samples, the amount of sorbed water was too minor to be detected reliably with the technique, but differences were
found when the energy values (J g−1) were compared. In the future work, the measurement set-up will be improved so that sorption rates less than 0.1 nmol s−1 can be measured repeatably and reliably.