Calcium regulation of carbohydrate modification in sorghum

Two improved Nigeria sorghum cultivars (KSV 8 and ICSV 400) were used to evaluate the effects of steep water Ca super(2+) treatment on carbohydrate modification in sorghum. The response of all the carbohydrate mobilization indicators evaluated that, a- and b- amylases, diastatic activity (DP), extract and cold water soluble carbohydrates (CWS-carbohydrates), to steep water Ca super(2+) treatment was highly significantly (p , 0.001) cultivar and steep water Ca super(2+) treatment dependent. In contrast to KSV 8, Ca super(2+) treatment generally caused significant repression of a- amylase development in ICSV 400. Development of b-amylolytic activity in KSV 8 was however, significantly repressed by Ca super(2+) treatment. Interestingly, b-amylase activity constituting well over 80% of total diastatic activity was attained in ICSV 400 grains subjected to 100 ppm Ca super(2+) treatment. Hot water extract (HWE) showed statistically insignificant (p . 0.1) linear variation with Ca super(2+) treatment. Although Ca super(2+) treatment significantly (p , .001) repressed CWS-carbohydrates in both cultivars, significantly higher CWS-carbohydrates and HWE were released in ICSV 400 for each DP unit than the corresponding DP in KSV 8 malts would permit. Thus, suggesting important roles for factors other than DP, possibly proteolysis, in determining HWE and CWS-carbohydrates. The benefits of reduced kernel growth and malting loss were neutralized by the general repression of carbohydrate modification indices for both cultivars.