Abstract

SOME NOTES ON THE CHARACTERISTICS OF WATER

Michele Vitolo*

ABSTRACT

Water is the smallest biomolecule (18 g/mol) found in all living organisms. The particular distribution of the atoms inside the water molecular structure leads to an imbalance of electrical charges, providing the biomolecule with a polarized configuration. Such condition allows the appearance of a weak chemical bond called hydrogen bond. Hydrogen bonds maintain the water molecules bound in any physical state (solid, liquid, and vapor), interfering with its colligative properties. Moreover, hydrogen bonds allow the dissolution of any hydrophilic substance in water, thus becoming a universal solvent. The dissolution of a salt mixture in water may result in a solution called buffer that resists to pH changing. Several biochemical events occur in a buffered medium. The enzyme activity, either in vivo (cell metabolism) or in vitro (industrial processes), is the most dependent event on water. Buffers such as H2CO3/HCO3- and oxy/deoxy hemoglobin contribute significantly to body homeostasis. Depending on the moisture content  expressed as water activity (AW)  in biological products (foods, medicines, cultures media, among others), product shelf life may decrease or increase. AW may vary from zero (dried product) to one (humid product).

Keywords: Water, buffers, colligative properties, water activity.