FOOD. Science. Technology. Quality

Food. SCIENCE. Technology. Quality

Food. Science. TECHNOLOGY. Quality

Food. Science. Technology. QUALITY




Effect of temperature on mass transfer in apples osmotically dehydrated in sucrose solution


The objective of this research was the analysis of mass transfer (i.e. of water and osmotic substance) in the tissue of osmotically dehydrated apples. The samples shaped as rectangular prisms of 25x25x10 mm were osmotically dehydrated in a 60 % sucrose solution at a temperature of 30, 50, and 70 °C for 180 minutes. It was showed that the result of the osmotic dehydration of apples was a mass loss that occurred as a consequence of a higher decrease in the water content compared to the gain in dry matter. The higher the temperature and the longer the dehydration time were, the larger the mass transfer inside the apple tissue was. The rise in temperature caused an increase in the process intensity of osmotic dehydration and, in consequence, the time during which the whole system tried to achieve a state of equilibrium state was shortened. After about 45 minutes of the osmotic dehydration of apples at a lower temperature (30 °C), the mass loss was comparable with the effect obtained during a significantly shorter time of dehydration (about 10 minutes), however, at a higher temperature (70 °C). The efficiency of this process was higher when the ratio: water loss in the osmotically dehydrated apples to gain of osmotic substance from the surrounding solution (WL/SG) was higher, and, as for the samples investigated, it equalled 2.7-5.2, but this value only insignificantly depended on temperature.


apples, osmotic dehydration, mass transfer, water loss, dry mass gain