Effect of temperature and pH on browning intensity
Absorbance at 420 nm is often used as an indicator of the extent of the Maillard reaction, since it symbolizes the advanced stage of the browning reaction (Morales & Jiménez-Pérez, 2001). Effect of heating temperature on browning intensity of Galactose-BCP MRPs and BCP is presented in Fig. 1(A), during heat treatment at pH 9.0 for up to 3 h. A significant difference of browning intensity between Galactose-BCP MRPs and BCP (P < 0.05) could be noted. A sharp incensement in A420 of Galactose-BCP MRPs was observed at heating temperature ranging from 70 to 120 °C (P < 0.05). The heating temperature showed a high correlation (R2 = 0.9126) with the browning intensity of Galactose-BCP MRPs. The browning intensity of Galactose-BCP MRPs was increased by 83-fold when temperature rose from 70 to 120 °C. Browning intensity of bovine casein peptides slightly increased when temperature ranged from 70 to 120 °C (P < 0.05). These results indicated that high temperature could enhance the browning of bovine casein peptides reacted with galactose.