Water transport in cellular tissues during thermal processing

Abstract

in Wiley Online Library (wileyonlinelibrary.com).Accurate modeling of water transport in food materials requires knowledge of how transport properties depend on the material structure. Water transport in a cellular tissue depends on its pathway (intracellular versus extracellular), which in turn depends on temperature. Using a combination of permeability measurement, pore-size distribution analysis and bioimpedance analysis, it is shown that water in a cellular tissue (e.g., potatoes) is mostly intracellular at lower temperatures at which cell membranes are intact. During drying at high-temperatures, cell membranes in potatoes are damaged, and the moisture transport pathway is primarily extracellular (through intercellular spaces and the lacunae created by the killed cells), with a much lower resistance to water transport. The difference in moisture diffusivity in potatoes for the two pathways has been estimated to be three orders of magnitude. Therefore, transport properties measured or predicted at low temperatures cannot be used for high temperatures because they correspond to different moisture migration pathways.

Effects of sodium alginate‐based coating pretreatment on drying characteristics and quality of heat pump dried scallop adductors

“…Finally, during drying of food materials, the driving force of water migration in the matrix is water and pressure gradient between intracellular and intercellular space. The gradient of water potential between cells and the intercellular spaces gradually decreases as drying proceeds . Shrinkage stress occurs owing to the unbalance of internal and external pressure of the food matrix, which subsequently results in tissue contraction or cellular shrinkage.…”

Microwave puffing: Determination of optimal conditions using a coupled multiphase porous media – Large deformation model

“…This is to account for the Klinkenberg effect, which is the enhanced gas flow due to slip flow of gas at pore walls when pore sizes are very small. The pore size distribution for potato has been reported as 0.542-3.88 lm (Halder et al, 2011) which makes it important to account for the Klinkenberg effect in this study. Conservation of energy includes heat transfer due to convection, conduction, phase change and microwave heating:…”

Effect of microwave and infrared drying over polyphenol content in Vaccinium meridionale (Swartz) dry leaves

“…Drying can be done by different techniques like near infrared furnace (resistance furnace), halogen bulb (far infrared), convection oven, lyophilization, microwave oven (2.45 GHz), among others (Wojdyło, Figiel, & Oszmiański, ). Such techniques allow water extraction from inside the vegetal porous matrix (Halder, Datta, & Spanswick, ), but water extraction from the matrix causes the extraction of organic compounds like polyphenols (Alean, Chejne, & Rojano, ; Rabeta & Vithyia, ).…”