Optimization of Rapid-Visco Analyser test conditions for predicting Asian noodle quality

A variety of Rapid-Visco Analyser (RVA) operating conditions have been tested with starch, flour, and wholemeal for predicting the quality of wheats for the manufacture of Japanese white-salted noodles. Using starch as the substrate, an initial temperature of 60 degrees C has been found to be optimum, and the best heating time from this initial temperature to the peak temperature of 95 degrees C was approximate to 6 min. Significant correlations were found between peak viscosity of starch pastes and noodle quality under these operating conditions. For flour and wholemeal samples, the correlations were not as high as for isolated starch. The correlations with wholemeal or flour and noodle quality could be improved by the addition of cr-amylase inhibitors. Measuring RVA viscosity of flour or wholemeal in the presence of silver nitrate gave viscosities which showed highly significant correlations with noodle quality. These correlations were similar to those obtained with isolated starch. It appears that the improvement is due to inhibition of the a-amylase present in grain and flour. Correlations were also observed between flour paste viscosity and alkaline noodle quality These could be increased either by inhibiting alpha-amylase with silver nitrate or by pH adjustment with sodium carbonate but the change was not significant. The improvement of the correlations by alpha-amylase inhibitors in this sample set was not as great as observed with Japanese white noodles.