EFFECTS OF AIR REST PERIOD ON THE MOBILIZATION OF SORGHUM RESERVE PROTEINS

The influence of air rest treatment period on the mobilisation of stor age proteins of two improved Nigerian sorghum cultivars ICSV 400 and K SV 8 was evaluated. Grains were steeped in distilled water for a total period of 48 h at 30 degrees C with a 6 h final warm steep at 40 degr ees C under four different cycles incorporating 1, 2, 3 or 4 h air res t period respectively. Cold water soluble protein, cold water soluble protein modification index, total cold water solubles, total free alph a amino acid nitrogen, carboxypeptidase and proteinase activities were determined after 6 days malting. All these protein modification indic es were highly significantly affected by length of air rest and cultiv ar, plus their pair-wise interactions. The levels of all these variabl es were also higher in sorghum cultivar ICSV 400 compared to KSV 8 exc ept for proteinase activity. Significant differences in grain storage protein complexity and structure coupled with probable differences in key proteinase iso-forms are advanced as possible explanation for the higher proteinase activity recorded in KSV 8 malts.