Effects of Salt Addition in Sugar Based Osmotic Dehydration on Mass Transfer and Browning Reaction of Green Pumpkin

The effects of immersion temperature and time, sugar concentration, and salt addition on water loss, solid gain, molality and rate parameter of green pumpkins during osmotic dehydration were analyzed by a response surface methodology, and osmotic dehydration effects on browning reduction of air-dried green pumpkins were also evaluated. The water loss, solid gain and molality are fast in the beginning of process and then increase slowly during remainder of the process. After 20 min of immersion time, water loss and solid gain of 100 g wet green pumpkin at , Brix sugar solution with 0, 2, 4% salt addition were 50.5, 54.8 and 58.6 g water loss and 10.4, 10.0 and 9.7 g solid gain, respectively. Based on the coefficients of determination, all second degree polynomial regression models were highly fitted to the experimental data at the level of 0.01%. Rate parameter, K, values were increased as the immersion temperature and sugar concentration increased. Browning degree was decreased as the immersion temperature, time and salt concentration increased. Minimum browning degree of dried green pumpkins (O.D. = 0.076) could be achieved using binary solutions (Brix sugar solution with 4% salt addition) with 20 min of immersion time compared to control (O.D. = 0.364) and blanching with 20 min of immersion time (O.D. = 0.122).