and OPA reactions were found almost same. This result was
not surprised as the calibration of pH-stat with both methods
was characterized by good linear correlations. Nielsen et
al. (2001) has also reported high correlation (r = 0.999) between
the TNBS and OPA method for soy protein hydrolysates. Hence,
considering all the results, the mean pK values of corn gluten
hydrolysates were obtained as 6.83, 6.59 and 6.36 for 40, 50 and
60 ◦C, respectively