Decortication induced changes in the physico-chemical, anti-nutrient, and functional properties of sorghum

[Display omitted] •Significant effect of decortication on milling characteristics.•Loss of both proximate composition and minerals owing to decortication.•Substantial reduction in total condensed tannins and phytic acid.•Whole grain flour suitable for emulsion-type food formulations.•Improvement in color properties of flour after decortication. The milling characteristics, physico-chemical properties, nutrient, and functional characteristics of sorghum were evaluated following field-level abrasive decortication to ascertain the impact of polishing parameters. Both grain moisture content and polishing time were found to significantly influence the degree of polish, endosperm yield, percentage broken, grain hardness, and thousand-grain weight. Both the proximate composition and mineral content of the flour decreased owing to decortication, indicating their dominant presence in the bran fractions. A more significant reduction in tannins was observed as compared to phytates meaning that phytates might be more localized in the inner layers, and tannins are majorly concentrated in the outer grain portions. Whole grain flour possessed better water and oil absorption capacities and lower bulk density value compared to polished fractions. There was also an increase in L* (lightness) and decrease in a* (red to green) and b* (yellow to blue) values in the polished flour samples indicating that decortication results in an overall improvement of the color of refined fractions. Results of PCA suggested a significant correlation between certain components namely fibre contents and tannin, ash content and mineral contents, and fibre and water absorption capacity, signifying that they co-vary with respect to one another. The cluster analysis suggested the importance of selected variables and their impact on the responses, as a clear demarcation was seen in the samples obtained from raw and polished grains.