Physicochemical and functional properties of starch from two sorghum varieties

Interest is growing in the use of sorghum (Sorghum bicolor [L.] Moench) as an energy source in production of animal feed and human food. This cereal can function as a precursor for different ingredients used as additives in the food industry. Physical grain properties were evaluated for two sorghum varieties (white and red), and physicochemical and functional property analyses done of their respective native starches. Structural, thermal and morphological properties of starch were determined using the amylose-amylopectin ratio, optical microscopy, environment scanning electron microscopy (ESEM), particle size distribution, differential scanning calorimetry (DSC) and X-ray diffraction. Grain physical and morphological properties differed due to size and weight, which vary by variety. Starch yields in both varieties were high and their composition highly pure. Their physicochemical, morphological and functional properties were most affected by the amylose-amylopectin ratio and level of heterogeneity in particle size and particle size distribution, the white sorghum starch had greater particle size heterogeneity, a larger proportion of small particles and higher grain compaction in the endosperm compared to the red sorghum starch. Both starches are potentially useful as ingredients in food industry applications.