2.7. Dynamic vapour sorption (DVS) analysis

The water vapour sorption–desorption isotherms of the spray dried samples were obtained at 25 °C using a DVS Advantage-1 instrument (Surface Measurements Systems Limited, London, UK). The samples were subjected to an initial equilibration under continuous nitrogen flow (to remove residual moisture) to determine the initial dry mass. Then, the relative humidity of the chamber was increased from of 0 to 90% RH, with 10% RH increments for the sorption cycles. Finally, the samples were subjected to a desorption cycle (i.e. decreasing relative humidity from 90 to 0% RH, with 10% RH decrements). Changes in the relative humidity occurred when the mass of the samples reached equilibrium (i.e. weight change over 10 min (dm/dt) ≤ 0.002 mg/min).