Three small-scale laboratory steeping and wet-milling procedures for isolation of starch from sorghum grains cultivated in Sahara of Algeria

Starch was isolated from white and red sorghum. The values of thousand kernel weight, test weight, starch and protein contents were respectively 33.05 ± 0.5 (g), 692.85 ± 0.65 (g/l), 65.05 ± 0.19% and 12.27 ± 0.18% for the white sorghum grains and 27.70 ± 0.13 (g), 736.55 ± 0.25 (g/l), 66.37 ± 0.31% and 12.59 ± 0.03% for the red sorghum grains.Three small-scale laboratory steeping procedures were used: steeping in NaOH solution, in SO2 solution and in SO2 solution containing lactic acid. The effect of the concentration of steeping solutions and time of steeping on starch isolate and yield were studied. The starch recovery, starch purity, moisture, amylose, protein content and particle size distribution ranged from 64.8% to 80.4%, 92.61 ± 0.54% to 99.29 ± 0.55%, 11.84% to 14.43%, 27.71 ± 0.41% to 29.88 ± 0.56%, 0.31 ± 0.01% to 0.78 ± 0.01% and 4.0 μm to 36 μm, respectively.The high grain quality traits and isolated starch properties indicated that Algerian sorghum cultivars can have many applications in nutrition and food technology.

► The major grain sorghum cultivars grown in Sahara of Algeria are white and red color. ► Some physical properties and the chemical composition of white and red sorghum grains were determined. ► Starch can be isolated from grain by a small-scale laboratory wet milling procedure. ► High percentage of starch with high purity was recovered. ► Starch isolates have some specific characteristics (granule size distribution, amylose content and granule shape).