Dry and hydro-thermal processing: A study on the nutritional, physical and functional attributes of raw and germinated sorghum flour

Sorghum is often subjected to different pre-treatments to improve its nutritional profile and palatability. However, selecting appropriate treatments and understanding their effects on sorghum are challenging. Therefore, an attempt was made to assess the effect of dry- and hydro-thermal treatments on the proximate, physical and functional properties of raw and germinated sorghum flour. The raw (R) and germinated (G) grains subjected to hydro-thermal treatment by blanching at 93 °C for 600 s, followed by drying to produce raw hydro-thermal treated (RHT) and germinated hydro-thermal treated (GHT) grains. For dry thermal treatment, sorghums were roasted at 150 ± 5 °C for 600 s to obtain raw dry-thermal treated (RDT) and germinated dry-thermal treated (GDT) grains. The dry-thermal treatment increased the bulk density and tapped bulk density, fat, fibre and carbohydrate content. In contrast, the hydro-thermal treatment increased all the physical properties, moisture and fat contents of raw and germinated sorghum flours. The water and oil absorption capacity was highest for raw-dry-thermally treated (229.40%) and germinated (185.40%) flours, respectively, while it was lowest for germinated (223.40%) and raw-hydro-thermally treated (173.65%) flours. The highest and lowest water retention capacity was observed for germinated (205.38%) and raw-dry-thermally treated (150.00%) flours. The FTIR spectra showed increased starch content and functional group activity due to thermal treatment. Dry- and hydro-thermal treatment conditions significantly alter sorghum flour's proximate, physical and functional properties.