Stability and colour characteristics of PEF-treated cyanidin-3-glucoside during storage

The stability and colour characteristics of PEF (pulsed electric field)-treated cyanidin-3-glucoside (Cy-3-glu) was investigated during storage at 4, 24 and 37 °C. The degradation of Cy-3-glu was analyzed using a first reaction kinetics while its colour characteristics was evaluated using colour indices such as colour density (CD) and CIE L∗a∗b∗ parameters. PEF had no post-effect on the stability and colour characteristics of Cy-3-glu during storage while the storage temperature had a significant effect (p < 0.05). The degradation of PEF-treated Cy-3-glu during storage conformed to the first-order reaction kinetics with regression coefficients R2 greater than 0.9300. Corresponding to 4, 24 and 37 °C, the degradation rate constant k in Cy-3-glu significantly increased in the exponential order level of 10−4, 10−3 and 10−2, while the t1/2 (the time that 50% Cy-3-glu degradation would take) and D-value (the time that 90% Cy-3-glu degradation would take) of Cy-3-glu during storage decreased in the exponential order level of 103, 102 and 10. The reduction of CD was closely related to the Cy-3-glu content in this study, the Cy-3-glu content was perfectly predicted using CD with a higher coefficient R2 > 0.9999. A significant decrease in b∗ and H0 value was obtained at all storage temperature (p < 0.05). A positive correlation was found between the Cy-3-glu content and b∗ value or H0 value with a coefficients R2 > 0.8400 during storage. ΔE increased significantly, ΔE was less than 2 at 4 °C while it was greater than 2 at 24 and 37 °C.