Optimization of Vapor Induced Puffing in Apple Dehydration

Vapor induced puffing during high temperature fluidized bed (HTFB) dehydration of apple cubes was optimized using response surface methodology (RSM). Osmoblanching in sugar syrup prevented enzymatic browning. Successtil puffing was achieved by creating a surface barrier to vapor by dipping the cubes in starch solution and manipulating the temperature and time of exposure in the HTFB. Optimum conditions for minimum bulk density with acceptable levels of nonenzymatic browning included dipping osmoblanched apple cubes in 1% starch solution, followed by HTFB drying 11 min at 157°C. Product bulk density exhibited a minimum while nonenzymatic browning values did not display an optimum. Minimum value of bulk density predicted by RSM and browning values were very close to those verified experimentally for product processed under the identified optimum conditions.