FOOD. Science. Technology. Quality

Food. SCIENCE. Technology. Quality

Food. Science. TECHNOLOGY. Quality

Food. Science. Technology. QUALITY




The effect of C-vitamin on the osmotic dehydration process in apples


Mild parameters of osmotic dehydration can be applied to the technology of manufacturing minimally processed foods. At the present time, there is a growing interest in the so called minimally processed foods with well retained, natural features of raw materials, i.e. nutritious values and sensory characteristics. The tissue-related semi-permeable structure of apples makes it possible to decrease the water content through osmotic de-hydration process and to incorporate additional substances contained in an immersed solution. In this work, there were analyzed changes in the water content level, dry matter, and vitamin C, all of them contained in the osmotically dehydrated apples. Apple samples shaped as 10 mm cubes were held in su-crose and in concentrated apple juice solutions with a 2% C-vitamin added. The solution concentration levels corresponded to water activity being 0.9. Temperatures were varied in a range from 20 to 40°C. The osmotic dehydration of apples was performed in a period from 0 to 180 minutes. The process of dehydrating apples in a solution of concentrated apple juice and of sucrose, ensuing in the presence of vitamin C, did not significantly affect the water content level nor the losses in the water content compared to the dehydrating process ensuing without the vitamin C. However, during the osmotic dehydration of apples in the presence of vitamin C, the noted gain in dry matter mass was about 50% in the concentrated apple juice solution, and about 30% in the sucrose solution. The presence of vitamin C impacted the rate of removing water from apples. At a temperature of 40°C, the rate of water removal from apples was almost double in value compared with the rate when no vitamin C was present during the dehydration process. The content of vitamin C depended on the process temperature, especially, in the case of the concentrated apple juice solution. The content of vitamin C in the material investigated increased along with the temperatures increasing from 20 to 40°C. The presence of vitamin C in the osmotic solution caused the conventional water diffusion coefficient to raise, and the osmotic substance to more intensely permeate the apples during their being osmotically dehy-drated.


osmotic dehydration, mass change, saccharose, concentrated apple juice, vitamin C