Bound water: its definition, estimation and characteristics

Abstract

Parameters of Caurie's [International Journal of Food Science and Technology 40 (2005) 283] unimolecular adsorption equation have been used to calculate total bound water to equal the square of the primary water capacity or m 0 2 grams. Current freezing methods predict bound water up to nm 0 grams which leaves a fraction of the total bound water with limited freezing properties unaccounted for. From these studies three types of bound water have been identified at room temperature along a decreasing energy gradient. It has been shown that the stability of processed and blended foods will improve with formula modifications consistent with expansion of type II bound water molecules and processed foods will be more stable the smaller the fractional ratio of type III to type II bound water molecules.

Effects of Moisture on the Mechanical Properties of Microcrystalline Cellulose and the Mobility of the Water Molecules as Studied by the Hybrid Molecular Mechanics–Molecular Dynamics Simulation Method

“…Those with restricted mobility can be considered as bound water while those with higher mobility are so‐called free water . The bound and free water terms are not yet standardized and their exact meaning depends on the different experimental techniques used to determine them, such as NMR, thermal analysis, dielectric measurement, viscoelastic measurement, and so on …”

Effect of bound water on the quality of dried Lentinus edodes during storage

“…The first two types of water can be easily removed during food drying process, whereas bound water has proved to be the main type of water in dried foods . Bound water is maintained in such a manner that the water‐driven chemical reactions and quality deterioration are not affected in dried foods but, due to absorption during storage, the bound water can show solvent or liquid‐like properties and may cause both chemical and enzymatic reactions . Bound water is therefore very important in the physical and chemical stability of dried foods with regard to lipid oxidation, enzyme activity, non‐enzymatic browning, and structural characteristics .…”

A method to correct the wide discrepancy between Brunauer, Emmett and Teller water and N2 surface areas of adsorbents

“…Equation indicates that the total surface area of an absorbent is directly proportional to n cm 3 pockets of space and inversely proportional to the diameter d of an adsorbate molecule with a constant of proportionality equal to 10 −6 . It is into these n cm 3 pockets of space per 100 g solids that a total of m 0 2 g of adsorbate molecules are bound in a single layer (Caurie, ).…”

“…In the proposed methods (eqns and ), the adsorbent surface is stated to be proportional to n cm 3 pockets of space. But by definition (Caurie, , ) n = m 0 /C 1/ n which reveals that in both the BET and the proposed methods, specific surface area is indeed directly proportional to the weight of primary adsorbate molecules or m 0 grams. In the proposed methods, however, a density factor C 1/ n is introduced that converts the m 0 grams from weight to volume units.…”