# Valorization of Spent Osmotic Solutions by Production of Powders by Spray Drying
## 4 Conclusions  
This study demonstrated that some of the tested spent osmotic solutions can be oxidized to produce powders via spray drying, although this possibility depends on the type of solution. The application of inulin as an alternative carrier was tested. The application of inulin as a drying carrier was not very efficient in the case of acacia honey, apple juice concentrate, chokeberry juice concentrate, and cherry juice concentrate solutions--the yield of drying was low. On the contrary, for sucrose and buckwheat honey solutions, it was at an acceptable level. Mannitol solution could also be powdered successfully, even without the addition of a carrier. However, as the material has different characteristics, it requires adjustment of the powder separation method--particles of crystalline structure, very small in size, and of low bulk density are difficult to discharge by the standard cyclone. It has to be highlighted that the physical properties of the powders are highly dependent on their susceptibility to stickiness during drying. Highly sticky materials (acacia honey, apple juice concentrate, chokeberry juice concentrate, and cherry juice concentrate solutions) had significantly larger particles of more regular size distribution, higher hygroscopicity, and higher bulk density, but better flowability (lower Hausner ratio).  
Thus, sucrose and buckwheat honey can be spray dried with inulin as a carrier to produce powders for further food applications, but for other tested materials, other types of carriers should be selected to avoid stickiness.  
Figure 4: HCA dendrogram showing the clustering of powders obtained from different raw materials—spent osmotic solutions: sucrose (SUC), honey buckwheat (BWH), acacia honey (ACH), apple juice concentrate (APP), chokeberry juice concentrate (CHO), cherry juice concentrate (CHE), and mannitol (MAN).  
**Author Contributions:** Conceptualization, K.S., K.K., I.M., and M.N.; methodology, A.B.-D., K.K., A.J., and M.N.; validation, R.C. and M.N.; formal analysis, K.K.; investigation, K.S., A.B.-D., K.K., and A.J.; data curation, K.S., A.B.-D., A.J., and K.K.; writing--original draft preparation, K.S., R.C., K.K., and I.M.; writing--review and editing, K.S. and R.C.; visualization, K.S. and R.C.; supervision, K.S.; funding acquisition, M.N. All authors have read and agreed to the published version of the manuscript.  
**Funding:** The research for this publication was carried out with the use of equipment purchased as part of the \"Food and Nutrition Centre--modernization of the WULS campus to create a Food and Nutrition Research and Development Centre (CziZ)\", co-financed by the European Union from the European Regional Development Fund under the Regional Operational Programme of the Mazowieckie Voivodeship for 2014-2020 (Project No. YMA.01.01.00-14-8276/17).  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** The data presented in this study are openly available in RepOD at [[https://doi.org/10.18150/9](https://doi.org/10.18150/9) QACDK]([https://doi.org/10.18150/9](https://doi.org/10.18150/9) QACDK) (accessed on 22 May 2025).  
**Acknowledgments:** The authors from Warsaw University of Life Sciences and the Polytechnic Institute of Coimbra express their gratitude to UNIGREEN European University for fostering collaboration and providing the opportunity to work together. This support and encouragement have been invaluable for the development of this research.  
**Conflicts of Interest:** The authors declare no conflicts of interest.