Relationships Among Grain Sorghum Quality Factors

Cereal Chern. 75(1):100-104 Correlations among grain sorghum quality factors (proximate composition, physical properties, and water absorption properties) were evaluated. Samples of 46 commercial hybrids (24 and 22 from crop years 1993 and 1994) were analyzed for starch, protein, crude free fat, test weight, absolute density, 1,000 kernel weight, percent kernel abraded, water absorption index, initial water absorption rate, and moisture saturation point. Test weight, absolute density, and percent kernel abraded were positively correlated among themselves (r > 0.5). Protein was negatively correlated with both test weight and absolute density (r < -0.5), while moisture Grain sorghum (Sorghum bicolor L. Moench) is an important crop in semiarid regions because of its drought resistance (Watson 1970). Lately, there has been increased interest in sorghum with respect to its potential for starch production because its wet-milling process is similar to that of corn (Subramanian et al 1994). There is also interest in the utilization of sorghum by-products such as surface wax and kafirin, the alcohol-soluble (prolamin) protein fraction. In contrast to rice and wheat, consumption of sorghum as a staple food in arid regions of Africa and Asia is so diverse that no single criterion of quality can be identified. This has hindered progress of plant breeders in selecting agronomically improved sorghum hybrids with acceptable grain quality (Cagampang and Kirleis 1984). Subramanian and J ambunathan (1981) established relationships among physicochemical characteristics of 45 sorghum hybrids. The 100 grain weight associated negatively with protein and positively with amylose content. Protein content showed a strong negative correlation with starch and water-soluble amylose contents in the grain and was positively related to water-soluble protein and ash contents. Starch content was positively associated with water-soluble amylose. Soluble sugars correlated positively with protein and negatively with amylose. Cagampang and Kirleis (1984) used selected physical and chemical measurements to determine grain quality of 15 sorghum hybrids differing widely in degree of hardness and vitreousness. Results of adhesion test, back-extrusion test, alkali gel stiffness test, and weight ratio of cooked to uncooked grain were strongly correlated with grain vitreousness. Fat, ash, total sugars, and water-soluble proteins were negatively correlated with hardness, whereas kafirin and amylose contents were positively correlated with vitreousness. Maxson et al (1971) studied 11 sorghum varieties of diverse genetic background with regard to the effect of milling time and physical properties of the grain on dry-milling performance. Endosperm texture (relative proportions of corneous to floury) was the property most highly correlated with milling yield. Density and hardness correlated inversely with milling yield. Endosperm texture was negatively correlated with hardness, test