## 3 Results and Discussion
### Ftir  
FTIR has been used to compare the secondary structure of the anthraquinone-loaded casein micelles (CMAQP, CMFDP, CMWLG) before and after spray-drying, as shown in Figure 4a,b. The controlled casein micelles (CMs) and anthraquinone-loaded casein micelles (CMAQP, CMFDP, CMWLAG) showed altered bands both in frequencies and intensities before (a) and after spray-drying (b). Generally, the FTIR spectra of casein micelles (Figure 4a,b) showed peaks for amide A band (3280-3225 cm\({}^{-1}\)), amide I (1700-1600 cm\({}^{-1}\)) amide II (1450-1550 cm\({}^{-1}\)) and amide III (1350-1200 cm\({}^{-1}\)) bands [62]. The discreetly intense peak near 1086 cm\({}^{-1}\) and 1065 cm\({}^{-1}\) can be related to phosphate stretching of colloidal calcium phosphate [63]. Spray drying of CMAQP shifted the amide I and amide II bands to higher and lower energy levels, respectively, as shown in Figure 4b. Before spray-drying, amide I bands were located at 1635 cm\({}^{-1}\) (Figure 4a), however, the amide I peak shifted from 1635 from 1642 cm\({}^{-1}\) after spray-drying. This shift to higher energy can be attributed to the shrinkage of protein structure upon spray-drying. The shifting in amide II bands in CMAQP Figure 4a towards lower energy from 1547 to 1537 cm\({}^{-1}\) indicates that upon spray-drying, the casein micelles have relaxed with a broader range of conformational geometry. These spectral changes are consistent with previous studies and can be attributed to the loosening and shrinkage of protein structure due to spray-drying. A change in intensities at 2980 and 2969 cm\({}^{-1}\) after spray-drying in CMQP corresponds to hydrophobic interactions [64], suggesting the methyl stretching of aliphatic chains of anthraquinones. These hydrophobic interactions are due to the accommodation of anthraquinones on hydrophobic regions of casein micelles after spray-drying that was attached to CM through hydrogen bondings while in solution. The secondary structure of casein micelles remained  
Figure 3: Scanning electron micrographs of freshly produced powders of CM controlled (**A**), CMAQP (**B**), CMFDP (**C**), and CMWLAG (**D**). Photographs (**1a–1d**) were taken originally using a magnification of 10,000\(\times\), and the scale bar 10 \(\upmu\)m scale, Photographs (**2a–2d**) were originally taken using a magnification of 5000\(\times\) and the scale bar 20 \(\upmu\)m, (**3a–3d** represent particle size distribution of CM control, CMAQP, CMFDP and CMWLAG, respectively). unchanged in CMAQP after spray-drying, suggesting the therapeutic effectiveness and functional properties of spray-dried anthraquinone-loaded casein micelles. The peak at 1065 cm\({}^{-1}\) after spray-drying in CMAQP corresponds to CCP due to rapid aggregation of CMs after spray-drying, which was absent before spray-drying in CMAQP. Regarding CMFDP (Figure 4b), the disappearance of amide I and amide II bands at 1641 and 1537 cm\({}^{-1}\), respectively, after spray demonstrated deformation of the casein micelle's structure due to folding and unfolding of casein micelles. Even before spray-drying (Figure 4a) in CMFDP, these bands are present at 1635 and 1545 cm\({}^{-1}\). This suggests that the secondary structure of casein micelles had been altered after drying. The strong peaks at 1065 cm\({}^{-1}\) in CMFDP after spray-drying (Figure 4b) correspond to calcium-casein complexes after the Maillard reaction that coated the surface of aggregated and reassembled casein micelles. However, these peaks were absent in the aqueous phase suggesting the absence Maillard reaction. Regarding CMWLAG, both amide I and amide II bands vanished after spray-drying. However, before spray-drying, a change in the amide II band and disappearance of amide I can be observed. The sharp peaks at 1065 cm\({}^{-1}\) in CMWLAG before spray-drying (Figure 4a) correspond to calcium phosphate liberation due to acid-induced precipitation of CMs [59]. However, after spray-drying, the peak intensity enhanced, suggesting the coating of calcium ions on the powdered surface.