# Characterization of Sorghum Processed through Dry Heat Treatment and Milling
## 2 Materials and Methods
### Methods  
#### 2.2.1 Functional Properties  
Hydration Capacity (HC)  
HC was evaluated in duplicate, following the protocol presented by [PERSON] et al. [23]. An amount of 5 g sorghum flour was weighed and mixed with 30 mL tap water by using a rod for 30 s every 10 min for 1 h. The rod was washed with 10 mL water at the end and the suspension was centrifuged for 20 min at 2300 rpm. The supernatant was discarded and the sample kept at 50 \({}^{\circ}\)C for 25 min, then it was weighed after reaching room temperature. The HC was calculated according to Equation (1):  
\[\text{HC }(\%)=\frac{(w_{2}-w_{0})-w_{1}}{w_{1}}\times 100 \tag{1}\]  
where \(w_{0}\) = tube weight, \(w_{1}\) = sample weight before analysis, and \(w_{2}\) = sample weight after water absorption.  
Oil-Absorption Capacity (OAC)  
OAC was evaluated in duplicate using a protocol adapted from the one described by [PERSON] and [PERSON] [24]. For this purpose, 3 g sorghum flour was mixed with sunflower oil (30 mL) and stirred for 1 min at 10 min intervals for 30 min. Then, the mix was centrifuged at 3000 rpm for 15 min, the supernatant discarded, and the pellet weighed after 5 min of draining. OAC was calculated using Equation (2):  
\[\text{OAC }(\%)=\frac{w_{1}}{w_{0}}\times 100 \tag{2}\]  
where \(w_{0}\) = sample weight before analysis and \(w_{1}\) = sample weight after supernatant discard.  
Water-Retention Capacity (WRC)  
WRC was evaluated in duplicate using the method presented by [PERSON] et al. [25]. An amount of 1 g sorghum flour was mixed with 30 mL distilled water and left for 18 h at room temperature in a sealed tube. After centrifugation at 3000 rpm for 20 min, the supernatant was discarded, the sample dried for 2 h at 105 \({}^{\circ}\)C in a convection oven, and weighed. WRC was calculated with Equation (3):  
\[\text{WRC }\left(\frac{\text{g}}{\text{g}}\right)=\frac{w_{1}-w_{2}}{w_{2}} \tag{3}\]  
where \(w_{1}\) = sample weight before drying an \(w_{2}\) = sample weight after drying.  
Swelling Power (SP)  
SP was evaluated in duplicate following the protocol described by [PERSON] and [PERSON] [24], with some modifications. The sorghum flour (0.5 g) was mixed with 15 mL distilled water and heated in a water bath at 90 \({}^{\circ}\)C for 30 min. After cooling at room temperature (15 min) and centrifugation at 3000 rpm for 25 min, the supernatant was discarded and the swollen sorghum flour sediment was weighed.  
Emulsion Activity (EA) and Stability (ES)  
The emulsifying characteristics of sorghum flour fractions were achieved in duplicate following the protocol presented by [PERSON] and [PERSON] [24]. For EA determination, 2 g sorghum flour was mixed with 20 mL distilled water at 4 \({}^{\circ}\)C and 20 mL of sunflower oil. After stirring for 20 min and centrifugation at 4000 rpm for 10 min, the height of the emulsion layer formed was measured. The EA was calculated with Equation (4):  
\[\text{EA }(\%)=\frac{H_{e}}{H_{\text{g}}}\times 100 \tag{4}\]where \(H_{e}\) = height of the emulsion layer and \(H_{w}\) = height of the whole layer.  
For ES evaluation, the emulsion formed in the previous step was heated in a water bath at 80 \({}^{\circ}\)C for 30 min, then it was cooled at room temperature for 20 min. After another centrifugation at 4000 rpm for 10 min, the height of the emulsified layer was measured and ES calculated with Equation (5):  
\[\text{ES}\;(\%)=\frac{H_{eh}}{H_{w}}\times\text{100} \tag{5}\]  
where \(H_{eh}\) = height of the emulsion layer after heating and \(H_{w}\) = height of the whole layer.