Cereal Chem. 70:739-743   |  VIEW ARTICLE

Effects of Flour-to-Water Ratio and Time of Testing on Sorghum Porridge Firmness as Determined by a Uniaxial Compression Test.

A. A. Mohamed, B. R. Hamaker, and A. Aboubacar. Copyright 1993 by the American Association of Cereal Chemists, Inc. 

A compression test was conducted on specimens of porridge made from seven sorghum cultivars with different endosperm textures. Porridge was prepared using three flour-to-water (F-W) ratios and was tested at 15, 30, or 60 min after cooking. Two parameters, apparent deformability modulus (E[app]) and yield stress (S[max]), were compared as measures of porridge firmness. Sticky porridges, which are usually softer than nonsticky ones, scored higher in terms of S[max] because of frictional or bonding effects. This discrepancy was absent for E[app], which was observed at lower stain levels. E[app] was also more reproducible than S[max], and it was sensitive enough to detect differences between cultivars. The effect of the F-W ratio was highly significant, as was that of time of testing (TT) (P less than 0.001). A cultivar X F- W ratio interaction was significant (P less than 0.01), indicating that the F-W ratio effect was not consistent across cultivars. Most cultivars exhibited improved porridge firmness as the F-W ratio increased, but they were ranked differently at the three ratios investigated. A cultivar X TT interaction was significant (P less than 0.01) and revealed that the rate of firmness development was higher for hard-endosperm cultivars than it was for soft ones. Cultivar ranking according to porridge firmness was also different at TTs of 15, 30, or 60 min after cooking. Firmness measured after 60 min correlated significantly with grain vitreousness and amylose content.