Effect of drying conditions on rehydration kinetics of sugar beet pulp

Abstract

© 2015 Nova Science Publishers, Inc. Dietary fibers are used for making numerous food products in various quantities and can be of different origin. The high moisture content of the sugar beet dietary fibers is suitable for the development of microorganisms, subsequently in order to extend the shelf life of sugar beet fibers they are dried. The drying process, which is necessary in order to obtain a product with high solid content, can significantly damage the sensory properties of dietary fiber (color, taste, texture, etc). Therefore, it is important to pay special attention to the choice of modes and parameters of the drying process. Rehydration of dried food products is one of the most important characteristics of this type of product. The changes that are monitored during the process of rehydration are the result of water penetration into the structure of the product. This process is based on diffusion, thus it is very dependent not only on the temperature of rehydration but also on the drying process parameters. For the purpose of modeling the rehydration process different models are applicable, among which the most commonly used are empirical models such as Peleg and Weibull model. The aim of this chapter is the examination of the influence of classical convective and microwave drying on rehydration of dietary fibers from sugar beet. Another goal was to investigate the effect of decolorizing pretreatment on the rehydration of sugar beet fibers. The experimental results suggest that Weibull and Peleg equations are good tool for description of the rehydration kinetics of sugar beet dietary fibers. The coefficients of determination (R2) are in range from 0.987 to 0.999 for Peleg equation whiles the Weibull equation within the limits of 0.984 to 0.999. Reciprocal values of Peleg equation parameters can be used to find dependences of the initial rate of rehydration and the equilibrium moisture content in the function of the drying temperature or power microwave drying and rehydration temperature using response surface methodology.