# Characterization of Sorghum Processed through Dry Heat Treatment and Milling
## 3 Results and Discussion
### Characterization of the Optimal Samples
#### 3.2.2 Color and Molecular Characteristics  
The color properties of optimal sorghum flours compared to the controls are presented in Table 7. No significant differences regarding \(L^{*}\), \(a^{*}\) and \(b^{*}\) values were recorded between Optimal S and Control S, while in the case of M and L fractions the optimal samples exhibited higher \(L^{*}\) and lower \(a^{*}\) and \(b^{*}\) compared to the controls. All the studied samples showed red nuances indicated by the positive values of \(a^{*}\) and yellow nuances suggested by the positive values of \(b^{*}\). Fraction dimension increase determined a decrease of \(L^{*}\), while the values of the \(a^{*}\) parameter increased. The color of sorghum products is influenced by the quantity and type of phenols and metal ions found in the grains [51]. The differences between the three fractions in terms of color and luminosity may be attributed to the distribution of these phenolics in the sorghum grain, it being known that the color of the pericarp seems to be generated by a combination of primarily anthocyanin and anthocyanin pigments and other flavonoid compounds [52]. [PERSON] et al. [51] reported an increase in redness of tortillas as the fraction size was higher due to the presence of larger quantities of bran. FT-IR spectra (Figure 5) interpretation allowed the identification of the main molecular characteristics of the optimal and control samples. The results obtained showed that for L fraction, the FT-IR spectra of the optimal sample registered some differences among peaks in the regions 1545, 1746 and 2338-2367 cm\({}^{-1}\) (Figure 5a). The peaks found at 1200 to 1900 cm\({}^{-1}\) indicate some functional groups and compounds, such as amides, amino acids, -C=O in aldehydes, C-O in esters, C'O in anhydrides, =O in lactones, \(t\)-butyl groups, N-O pyridine groups, esters, lactones, etc. [14]. Changes in the amide II fraction after dry heat treatment can be observed at 1545 cm\({}^{-1}\), which is given by the joining of N-H bond vibrations with CN stretching [53]. A prominent peak was observed at 1746 cm\({}^{-1}\) for the Optimal L sample, suggesting the changes of amide I fractions caused by the heat treatment that determined denaturation of sorghum proteins. The differences in the 2338-2367 cm\({}^{-1}\) regions could be related to the browning reactions that may occur during heat treatment \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Property**} & \multicolumn{5}{c}{**Sample**} \\ \cline{2-6}  & **Optimal S** & **Control S** & **Optimal M** & **Control M** & **Optimal L** & **Control L** \\ \hline \(L^{*}\) & 85.23 \(\pm\) 0.04 \({}^{\text{SF}}\) & 85.51 \(\pm\) 0.03 \({}^{\text{ACh}}\) & 84.54 \(\pm\) 0.04 \({}^{\text{MC}}\) & 83.25 \(\pm\) 0.07 \({}^{\text{AB}}\) & 78.88 \(\pm\) 0.12 \({}^{\text{H}}\) & 77.08 \(\pm\) 0.17 \({}^{\text{KC}}\) \\ \(a^{*}\) & 0.97 \(\pm\) 0.01 \({}^{\text{SF}}\) & 0.78 \(\pm\) 0.03 \({}^{\text{NC}}\) & 1.11 \(\pm\) 0.02 \({}^{\text{ZF}}\) & 1.23 \(\pm\) 0.03 \({}^{\text{NB}}\) & 1.11 \(\pm\) 0.05 \({}^{\text{KG}}\) & 1.93 \(\pm\) 0.03 \({}^{\text{JA}}\) \\ \(b^{*}\) & 11.68 \(\pm\) 0.07 \({}^{\text{SF}}\) & 11.69 \(\pm\) 0.01 \({}^{\text{JC}}\) & 12.00 \(\pm\) 0.05 \({}^{\text{GC}}\) & 12.63 \(\pm\) 0.01 \({}^{\text{NB}}\) & 15.24 \(\pm\) 0.04 \({}^{\text{HH}}\) & 15.80 \(\pm\) 0.11 \({}^{\text{JA}}\) \\ \(\alpha\)-helix/\(\beta\) sheets & 3.80 \(\pm\) 0.37 \({}^{\text{SF}}\) & 2.11 \(\pm\) 0.15 \({}^{\text{YA}}\) & 2.46 \(\pm\) 0.09 \({}^{\text{WG}}\) & 3.01 \(\pm\) 0.69 \({}^{\text{WA}}\) & 1.66 \(\pm\) 0.21 \({}^{\text{IH}}\) & 2.36 \(\pm\) 0.02 \({}^{\text{JA}}\) \\ Crystallin/amorphous & 1.96 \(\pm\) 0.00 \({}^{\text{MG}}\) & 1.06 \(\pm\) 0.01 \({}^{\text{NB}}\) & 1.79 \(\pm\) 0.02 \({}^{\text{WH}}\) & 1.05 \(\pm\) 0.01 \({}^{\text{AB}}\) & 2.03 \(\pm\) 0.03 \({}^{\text{JF}}\) & 2.06 \(\pm\) 0.16 \({}^{\text{JA}}\) \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Color and molecular characteristics of optimal and control samples.