## 3 Results and Discussion
This means that the sample was brighter compared to the FD and CD powders. Similar relationships were obtained for the sensory colour evaluation of the powders; the colour of the SD powder was evaluated as light red and that of the FD and CD samples as dark red. The values of parameter a* determined for the SD powder and the FD powder were also higher as compared to the CD powder, which means that the SD and FD samples had a greater colour shift towards red. There were no major differences in the colour parameter b* for all samples tested, which means that these samples had a similar shade of yellow. Taking into account the RGB colour model, it can be seen that the SD and FD powders showed higher R values compared to the CD powder, which indicates that the SD and FD powders had a higher saturation of red colour. The value of the colour parameter B (blue) was the highest for the SD powder, which indicates that it was more saturated with blue colour. No major differences were observed for the green colour (parameter G). The results obtained in the colour of the powders evaluated by the instrumental method and the subjective sensory evaluation show a large difference in the colour of the powders obtained by different methods. Long-lasting drying of fruit by the CD method at 70 \({}^{\circ}\)C caused large changes in the content of anthocyanins, providing a characteristic colour change for strawberries (light red) towards dark red (brown). The resulting differences in the colour of the powders depending on the method of preparation should be taken into account in their selection as natural food colouring additives. The CD powders were characterised by a different dark red/brown colour, as opposed to the FD and SD powders, which were light red. Figure 1: Sensory quality of strawberry drinks prepared with FD, CD and SD powders (a–d: values marked by different letters differ significantly (\(p<0.05\)); FD: freeze drying, CD: convective drying, SD: spray drying). Figure 2: Graphical interpretation of strawberry powders colour distribution using the instrumental method (‘electronic eye’). (**a**) CD powder; (**b**) FD powder; (**c**) SD powder. In order to determine whether there is a relationship between the tested properties of the powders and their microstructure, images of their surfaces were taken with a scanning electron microscope (Figure 3). In the powders obtained from FD and CD strawberries, the original, porous structure of the fruit was largely destroyed as a result of the grinding process. This had a marked impact on the physical properties, especially WHC, which was only slightly higher in FD powders than in CD ones, where large changes occurred, deforming the texture of the fruit. In the FD powders, along with the destruction of the original spongy structure, these valuable properties of water absorption were much lower. A larger number of pores and a less firm, more easily disintegrating structure could have an impact on obtaining higher WSI values compared to the CD powders. In the SD powders, water was quickly evaporated at a high temperature with a high rotary atomiser speed, which resulted in the formation of round and oval shapes with some concavities on the surface, and multiple creases and other deformations. The solubility of the SD powders was high (WSI 885.4 g kg\({}^{-1}\)), which was a result of both the processing method and their composition (juice with the carrier). The obtained microstructure images and their relationships to the properties of strawberry powders prepared using the studied methods are similar to the results obtained in previous studies by the authors of this \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Colour Code**} & \multicolumn{6}{c}{**CD**} \\ \cline{2-7}  & **L** & **a** & **b** & **R** & **G** & **B** \\ \hline  
\hline \hline \end{tabular}
\end{table} 
Table 3: Colour parameters in L*a*b* and RGB space obtained for organic strawberry powders prepared by various methods (FD: freeze drying, CD: convective drying, SD: spray drying).