Thermal, structural and spectroscopic properties of powder sheep milk obtained by different drying methods

The thermal, microstructural and spectroscopic properties of sheep's milk powder submitted to atomisation and freeze-drying were evaluated. Composition analysis, mid-infrared spectroscopy (MIR), scanning electron microscopy (SEM) and thermal analysis were performed. The MIR spectra showed similar vibration modes associated with each peak, but with a difference in absorption intensity. The SEM images revealed that the milk powder obtained by the atomisation method produced particles with a spherical and wrinkled shape, while the particles obtained by the freeze-drying method showed a continuous structure. Thermal analysis indicated one endothermic peak and four exothermic peaks for atomised milks, while for freeze-dried milks one endothermic peak and three exothermic peaks. MIR analysis showed that the milk powder obtained through atomisation had higher contents than the milk obtained through freeze-drying. This confirms that the atomisation method is more suitable for obtaining milk powder, mainly because it is a cost-effective technique compared with freeze-drying.(c) 2023 Elsevier Ltd. All rights reserved.