%0 Journal Article
%T Microwave-Osmotic Dehydration of Cranberries under Continuous Flow Medium Spray Conditions
%A Derek Wray
%A Hosahalli S. Ramaswamy
%J International Journal of Microwave Science and Technology
%D 2013
%I Hindawi Publishing Corporation
%R 10.1155/2013/207308
%X Microwave-osmotic dehydration of cranberries was evaluated under continuous flow medium spray (MWODS) conditions after some pretreatments. A central composite rotatable design was used with three input variables at five levels (temperature, 33¡ãC¨C67¡ãC; sucrose concentration, 33¡ãB¨C67¡ãB; and contact time, 5¨C55£¿min). Responses were moisture loss (ML), solids gain (SG), and weight reduction (WR) as well as color and texture parameters. The responses were related to process variables using response surface methodology and statistical analysis: each model was tested for lack of fit to assure nonsignificance and each process variable was tested for significance . Temperature was found to have the most prominent effect as it was significant with all drying (ML, SG, and WR) and quality (hardness and chewiness) parameters, while contact time was found to be significant with ML and WR. Concentration wasn¡¯t found to be significant for any response. Increasing skin pretreatment severity generally promoted SG but had little effect on ML. The exception was chemical peeling, which favored ML but had no effect on SG. Overall, MWODS enables food dehydration in a much faster period of time than conventional osmotic dehydration (COD), while specifically promoting moisture loss over solids gain. 1. Introduction Dehydration is one of the oldest methods of food preservation and is still prevalent in the food industry. The main objective of the dehydration process is to remove moisture to a point where the product is microbiologically and enzymatically stable and limit product deterioration during storage [1]. There is also an interest in producing dried ingredients which can then be incorporated into other products like breakfast cereals or baked goods. Drying often results in degradation of flavor volatiles, deterioration of color and texture, and an overall decrease in nutritional value, largely due to exposure to high temperatures for long periods of time in the presence of air [2]. Therefore, the key to improving the quality of dried products is to limit changes to the aforementioned quality characteristics during processing. Osmotic dehydration (OD) represents a mild processing step in which texture is only moderately affected, nutritional value is well maintained, and the product quality, especially the color, can often be enhanced throughout the process [3]. In osmotic dehydration, the driving force is the osmotic pressure across a semipermeable membrane, which in food products is the cell wall. In addition to water exiting the plant tissue there is also a
%U http://www.hindawi.com/journals/ijmst/2013/207308/