Influence of milling methods and particle size on hydration properties of sorghum flour and quality of sorghum biscuits

• Particle size heterogeneity of sorghum flour affects hydration properties.
• Traditional milled flour has good functional properties to prepare sorghum biscuits.
• Traditional milled flour larger particle sizes (251 μm and 180 μm) were suitable for the preparation of biscuits.

The sorghum flour of different particle sizes (251, 178, 152, 104 and 75 μm) made from traditional milling process and hammer mill were obtained using different sieves and evaluated for hydration properties. Biscuits were prepared using the respective flours of various particle sizes and the physical, textural and organoleptic properties were evaluated. With the decrease in particle size of flour, the water absorption capacity (P < 0.05) and swelling power (P < 0.01) increased, Water binding capacity and oil binding capacity decreased (P < 0.05) in hammer milled flour than traditionally milled flour. The hardness (texture) was higher in biscuits prepared from flour of particle size 152, 104 and 75 μm compared to 251 μm and 180 μm. The color of biscuits was affected by the milling process, L* and b* were higher (P < 0.01) in hammer milled flour and a* and whiteness index were higher in traditionally milled flour. Acceptability was higher in biscuits prepared from the traditionally milled flour of particle sizes 251 μm and 180 μm.