The first-order reaction kinetics were determined for
chlorophyll degradation and visual colour loss in
blanched green peas in buffered solutions of pH 5.5, 6.5
and 7.5 in the temperature range 70–100 C. The rate constants
of green colour loss and chlorophyll degradation
decreased with increasing pH, indicating that the green
colour was retained at higher pH conditions. It was found
that chlorophyll a degraded faster than chlorophyll b at
all pH values for each temperature applied. The results
revealed that chlorophyll a was more susceptible to thermal
degradation than chlorophyll b in acidic conditions.
The significant relationship (r = 0.9301–0.9986; p < 0.05)
found between the change of visual colour parameters
(a, a/b and h values) and degradation of chlorophyll
a, as well as chlorophyll b (r = 0.9141–0.9984; p < 0.05),
indicated that the objective colour measurements can be
used for determining the degradation kinetics of chlorophyll
a and b instead of expensive and time-consuming
HPLC analysis.