OPTIMIZATION OF RAPID-VISCO ANALYZER 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 o f wheats for the manufacture of Japanese white-salted noodles. Using s tarch as the substrate, an initial temperature of 60 degrees C has bee n found to be optimum, and the best heating time from this initial tem perature to the peak temperature of 95 degrees C was approximate to 6 min. Significant correlations were found between peak viscosity of sta rch pastes and noodle quality under these operating conditions. For fl our and wholemeal samples, the correlations were not as high as for is olated starch. The correlations with wholemeal or flour and noodle qua lity could be improved by the addition of cr-amylase inhibitors. Measu ring RVA viscosity of flour or wholemeal in the presence of silver nit rate gave viscosities which showed highly significant correlations wit h noodle quality. These correlations were similar to those obtained wi th isolated starch. It appears that the improvement is due to inhibiti on of the a-amylase present in grain and flour. Correlations were also observed between flour paste viscosity and alkaline noodle quality Th ese could be increased either by inhibiting alpha-amylase with silver nitrate or by pH adjustment with sodium carbonate but the change was n ot significant. The improvement of the correlations by alpha-amylase i nhibitors in this sample set was not as great as observed with Japanes e white noodles.