Effects of salt and alkaline reagents on dynamic rheological properties of raw Oriental wheat noodles

To gain further understanding of the functionality of ingredients in oriental wheat noodles, the rheological properties of raw noodles made using high protein (Red Bicycle) or low protein (Sandow) wheat flours and various additives (salt or alkaline reagents at concentrations of 0, 0.1, 0.5, 1.0, 2.0, 3.0, and 4.0%) were investigated using frequency sweep and temperature sweep oscillatory tests. Generally, both the elastic modulus (G') and viscous modulus (G") of raw noodles increased when various levels of salt or alkaline (kansui and NaOH) reagents were included in the formulation, with the exception of Red Bicycle noodles where the G" was not significantly affected by the salt. The G' was significantly decreased in the presence of sodium chloride at concentrations less than or equal to 4.0% and kansui at <0.5%. The change in rheological properties of raw noodles was related to the wheat flour quality, type, level of additive, and frequency. The G', G", phase angle, and complex viscosity changed in a similar pattern when raw noodles were heated from 25 to 100 degrees C. These parameters decreased initially with increasing temperature until they reached a valley and then increased either to a plateau or continuously in noodles containing kansui. The appearance of valley points at 75.5 and 77.2 degrees C during heating of Sandow and Red Bicycle noodles containing salt, and 89.4, and 83.2 degrees C during heating of Sandow and Red Bicycle noodles containing kansui, respectively, was not associated with starch gelatinization as determined using differential scanning calorimetry. The continuous increase in G', G", and complex viscosity observed with noodles containing kansui during the hold period at 100 degrees C was attributed to the high pH environment and not to the inactivation of alpha-amylase.