The presence of polyphenol oxidase (PPO) impairs the quality of prepared fruits and vegetables and limits their
commercialization in the market. Therefore, this study investigated effects of conventional blanching at 80-90
°C for 60-240 s on PPO inactivation and color of pumpkin sticks and slices. Fresh pumpkin was rich in nutrition
(9.70±0.48 % protein, 0.14±0.01 % fat, 4.13±0.04 % ash, 7.68±0.38 % crude fiber, 78.35±0.82 % carbohydrate
and 117.42±1.70 mg/100 g carotenoid); however, the intense PPO activity (62.54±3.09 U/g dry matter) implied
it was prone to browning reactions. The results demonstrated that PPO activity from pumpkins decreased with
the increasing blanching temperature and time. PPO inactivation kinetics followed the first-order model with
large determination coefficients (R2 = 0.81-0.97) and recorded kinetic parameters at 90 °C were k =
130.49±21.28x10-4 s-1, D = 179±27 s, Ea = 152±33 kJ.mol-1, and z = 13.61±0.76 °C (pumpkin sticks); or k =
142.82±17.84x10-4 s-1, D = 163±22 s, Ea = 91±22 kJ.mol-1, and z = 10.84±0.88 °C (pumpkin slices). These
findings indicated that pumpkin slices were more sensitive to temperature increase than pumpkin sticks;
however, the D values showed no significant differences (p > 0.05). The surface color of pumpkins was also
reduced significantly during blanching, with a higher color retain in pumpkin slices (L* = 84 %, a = 61 %, and b
= 74 % of its initial values).