Characteristics of Isolated Starch Granules of Two Sorghum Varieties
Sorghum, like other cereals, is a good source of starch, that reached to about 60– 80% of kernels which had an brilliant potential for global industrial claims. In this study, starch had been isolated from tow sorghum varieties (low tannin; Giza 15 and high tannin; Assiut 14) using different extraction procedures (boiling in water and in alkaline media and soaking in alkaline media).Starch yield, gel consistencies, degree of syneresis, gelatinization temperature range, shape and size of starch granules, and starch color had been assayed for the isolated starch. The results revealed that Giza 15 had higher starch yield for all extraction procedures, gels made from (Giza 15) was thinnest than that made from (Assiut 14), the degree of syneresis increased by way of starch gel decrease. Results also showed that neither significant difference of gelatinization temperature between white and pigmented sorghum starches nor between the extractions procedure for the pigmented starch was noted. Giza 15 starch had the highest L* value (91.3) however Assiut 14 variety gave a little darker starch. The pigmented sorghum starch appearance was comparable to that of white variety. The starch granules were mostly spherical and polygonal, with indentations and pores on the surface radial, tube-like channels of granules penetrate from the external surface into a cavity at the hilum, starch granule size of Giza 15 exhibited not significantly difference for larger size compared to that of Assiut 14 extracted using different extraction procedures. The result concluded that the starch isolated from pigmented sorghum grains using the alkaline procedure was comparable to white starches; thereby it could be replace it in the food industry fields.