Abstract:

The effect of temperature on firmness degradation kinetics and microstructure of apples was investigated during pulsed vacuum osmodehydration. The samples submerged in 55% (W/W) sucrose solution were dehydrated for 8 h at 25 ℃, 40 ℃ and 50 ℃ under pulsed vacuum condition, respectively. The results indicated that the rate of firmness loss is high in the initial stage and relatively slow in the later stage with the increase of time, and the firmness loss and 1/k1 values increase with the increase of the osmosis temperature. Peleg’s model could reasonably describe firmness degradation kinetics of the apples under examined conditions, and the value of activation energy is 31182 J/mol. The osmotic temperature of 50 ℃ leads to the largest amount of firmness loss, the severest cell modification and structure collapse of osmodehydrated apples.

Key words: apple, firmness, pulsed vacuum osmodehydration, Peleg’s model, microstructure