## 3 Results and Discussions
### Mean Particle Size of Bio-Calcium and Calcine Bones  
All samples showed differences in the mean diameter (d\({}_{\text{d3}}\)), which ranged from 22.21 to 27.53 \(\upmu\)m. Bio-cal-A showed larger particle size than Bio-cal-H (\(p<0.05\)) (Table 2). For Cal-A, the higher calcination time resulted in the decrease in particle size. On the other hand, a slightly higher size was found for Cal-H when calcination time was increased (\(p<0.05\)). Bio-cal-A showed a bi-modal distribution because of non-homogenous particles as indicated by the peak with the shoulder, while Bio-cal-H showed a mono-modal distribution, indicating the presence of homogeneous particles (Figure 2). The surface moisture, protein, and fat concentration are the factors affecting the stickiness and agglomeration of particles, thus influencing the particle size distribution [26]. During alkaline treatment, the collagen in the bone matrix, which is tightly linked with HAp, might be removed. This could bring about the weakened matrix, and the size could be reduced with ease.  
For calcined samples, Cal-A and Cal-H had a more ordered and compact form with uniform particle size distribution as shown by mono-modal distribution. In addition, the removal of organic compounds possibly resulted in the lower particle diameters due to more compactness of HAp.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline
**Parameters** & **Bio-Cal-A** & **Bio-Cal-H** & **Cal-A (6 h)** & **Cal-H (6 h)** & **Cal-A (9 h)** & **Cal-H (9 h)** \\ \hline Mean particle size (d\({}_{\text{d3}}\), \(\upmu\)m) & 26.53 \(\pm\) 3.49 \({}^{d}\) & 24.05 \(\pm\) 3.14 \({}^{d}\) & 25.36 \(\pm\) 2.78 \({}^{d}\) & 22.21 \(\pm\) 2.84 \({}^{d}\) & 22.39 \(\pm\) 2.64 \({}^{b}\) & 23.12 \(\pm\) 2.94 \({}^{c}\) \\ L\({}^{*}\) & 95.29 \(\pm\) 0.08 \({}^{d}\) & 94.84 \(\pm\) 0.08 \({}^{d}\) & 93.61 \(\pm\) 0.01 \({}^{d}\) & 69.49 \(\pm\) 0.04 \({}^{d}\) & 95.01 \(\pm\) 0.01 \({}^{d}\) & 80.68 \(\pm\) 0.01 \({}^{b}\) \\ A\({}^{*}\) & \({}^{-0.60}\pm 0.02\)\({}^{c}\) & \({}^{-0.31}\pm 0.07\)\({}^{d}\) & \({}^{-1.59}\pm 0.01\)\({}^{b}\) & \({}^{-0.23}\pm 0.04\)\({}^{e}\) & \({}^{-2.63}\pm 0.01\)\({}^{a}\) & \({}^{-0.36}\pm 0.03\)\({}^{d}\) \\ B\({}^{*}\) & 7.13 \(\pm\) 0.02 \({}^{d}\) & 6.86 \(\pm\) 0.14 \({}^{c}\) & \({}^{-0.19}\pm 0.02\)\({}^{b}\) & \({}^{-0.10}\pm 0.07\)\({}^{b}\) & \({}^{-1.67}\pm 0.01\)\({}^{a}\) & \({}^{-0.22}\pm 0.01\)\({}^{b}\) \\ \(\Delta\)E\({}^{*}\) & 6.94 \(\pm\) 0.12 \({}^{d}\) & 6.60 \(\pm\) 0.08 \({}^{c}\) & 0.87 \(\pm\) 0.14 \({}^{a}\) & 24.15 \(\pm\) 0.15 \({}^{d}\) & 3.00 \(\pm\) 0.14 \({}^{b}\) & 12.97 \(\pm\) 0.09 \({}^{e}\) \\ \(\Delta\)C\({}^{*}\) & 7.15 \(\pm\) 0.03 \({}^{f}\) & 6.87 \(\pm\) 0.14 \({}^{e}\) & 1.60 \(\pm\) 0.01 \({}^{c}\) & 0.26 \(\pm\) 0.06 \({}^{a}\) & 3.11 \(\pm\) 0.00 \({}^{d}\) & 0.42 \(\pm\) 0.01 \({}^{b}\) \\ \hline Values are presented as mean \(\pm\) SD (n = 3). Different lowercase letters in the same row indicate significant difference (\(p<0.05\)). & & & & & \\ \end{tabular}
\end{table}
Table 2: Mean particle size and color values of bio-calcium and calcined powders from salmon frame.  
Figure 2: Particle size distribution of bio-calcium and calcined bone powders from salmon bones.  
Therefore, the particle size distribution was greatly affected by the alkaline pre-treatment and calcination temperatures.