FOOD. Science. Technology. Quality

Food. SCIENCE. Technology. Quality

Food. Science. TECHNOLOGY. Quality

Food. Science. Technology. QUALITY




Mass exchange in osmotic dehydration process of kiwi fruits


Removing water from fruit tissue using a drying method causes their nutritional value and sensory properties to change. On the other hand, more and more people are continuously interested in products showing a low processing degree. Therefore, technologies are searched to produce functional products of high nutritional value and, at the same time, consumer-friendly and ready-to eat. Osmotic dehydration is a very gentle method of partially removing water from a plant tissue. The objective of this study was to analyze kinetics of osmotic dehydration of green kiwi fruit. The impact was examined of the dehydration temperature on changes in: mass loss, water content, water loss, dry matter increase, and solids gain. The osmotic dehydration was performed in a 61.5% sucrose solution, during periods ranging from 0 to 300 minutes, at three temperatures: 25, 35, and 45 °C. A ratio: kiwi mass to osmotic solution mass was 1:5. The research performed showed that the osmotic dehydration was the most dynamic process during the first hour, i.e. during this time, the highest mass and water loss were reported, as were the highest increases in dry matter and solids gain, regardless of the process temperature. During the osmotic dehydration process, a material shrinkage was found to occur along with the water loss. The process parameters impacted the changes in the thickness of kiwi slices. Along with the increase in the temperature and with the extension of the process time, the thickness of kiwi slices decreased. Furthermore, the effectiveness coefficient of osmotic dehydration was determined; it was the highest for the dehydration process running at the highest temperature. The efficiency of the process became constant after 60 minutes, when the process was carried out at a temperature of 45 °C, and after ca. 30 minutes at a temperature of 25 and 35 °C.


green kiwi, dehydration effectiveness, content of solids, slices thickness