EFFECT OF OSMOTIC-AIR DEHYDRATION ON DRYING KINETICS AND MICROSTRUCTURE OF APPLE SLICES AND CUBES | ||||
| Journal of Food and Dairy Sciences | ||||
| Article 11, Volume 6, Issue 5, May 2015, Page 405-418 PDF (873.97 K) | ||||
| Document Type: Original Article | ||||
| DOI: 10.21608/jfds.2015.48852 | ||||
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| Authors | ||||
| M. K. Qubasi; L. A. H. Shekib; N. M. Elshimy; H. M. Mousa | ||||
| Food Science and Technology Dept., Fac. Of Agric, Alexandria Univ., 21545, El-Shatby, Alexandria, Egypt. | ||||
| Abstract | ||||
| Osmotic dehydration (OD) is a process of water removal from a high-moisture solid food by pressure created by a surrounding liquid medium. Meanwhile, air dehydration of foods involves vaporization of water and removal of the vapor with a stream of air. Major problems associated with air dehydration are poor product quality, unfavorable changes in color, flavor and nutritive value of dried products. The process of osmotic dehydration followed by air drying of apples was studied to improve the quality of dried apples, so it could be consumed as snake foods. Apple slices and cubes were initially immersed in sucrose solutions (40 or 50%) for 12 hours, according to the results of preliminary experiments for osmotic dehydration. Kinetic studies during soaking in osmotic solution show that soaking apples in 50% of sucrose solution resulted in increasing the solid gain (SG), water loss (WL) and weight reduction (WR) comparing to those which were soaked in 40% of sucrose solution. Also, apple slices had higher values for the forementioned parameters than cube ones. Moreover, kinetic studies during drying by hot air revealed that osmotic-air dried apples which were soaked in 40% of sugar solution had less drying time, higher (WL) and higher (WR) than those which were treated with 50%. Also, apple slices had better results than the cubes. Microstructure changes using scanning electron microscope in osmotic-air dried apple tissues were studied. The concentration of the soaking sugar solution affected the microstructure of both apple slices and cubes. Osmotic dried apple slices and cubes which were soaked in 50% resulted in higher cell shrinkage than those which were treated with 40% of sucrose solution. | ||||
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