Physico-chemical and rheological properties of modified corn starches and its effect on noodle quality

In this study, three different modification methods (pregelatinization, acid-thinning and dextrinization) were used to produce the modified corn starches. Physicochemical and rheological properties of the native and modified corn starch were studied. In addition, the resultant modified corn starches were used at levels 5%, 10% and 15% to replace wheat flour in noodle processing.The crude protein and lipid contents of modified corn starches significantly decreased compared to native ones. Water and oil binding capacity of corn starch increased up to 1.49 and 2.35 g/g, respectively, after modifying by the pregelatinization method. Results also showed that the maximumsolubility was given by dextrinized corn starch after heat treatment at 90°C being 44.85%, which means about 5.9-fold increase in solubility as compared to native starch. However, acid-thinning modified corn starch showed a significant decreased effect on the syneresis of its gel in comparison to those of other modified starches and the native one. The maximum viscosity decreased in pregelatinized starch followed by acid-thinned starch in comparison to native corn starch. The same trend was found in the viscosity after holding at 95 °C for 15 min. The highest noodle weight and volume increases were recorded for noodles containing 5% and 10% of native corn starch followed by 10% of pregelatinized corn starch, as well as, the control. Replacing wheat flour with 5%, 10% and 15% of native or pregelatinized corn starch did not cause any negative effects on sensory attributes of noodles in comparison to the control sample. Finally, it could be concluded that the native and pregelatinized corn starch can be used up to 15% in noodle processing with high quality and acceptable sensory attributes.