physicochemical properties of the universal solvent, water.
second only to oxygen, water is crucial to the existence of all
living organisms; they can live without food for a few weeks but
for only a few days without water. Being an integral part of
animal and vegetable tissues, water serves as an excellent medium
for the cellular reactions. It functions in the digestion,
absorption, transport of nutrients, and excretion of waste
products. Water helps to maintain the electrolyte balance and
temperature of the body. It is either a reactant or a product in
many of the reactions.
is the basic molecule of life, forming the natural environment of
the cells. It constitutes an interface for exchanges that occur
between living and nonliving regions, thus connecting the physical
world with the biological one. Water is widely distributed in its
solid, liquid, or gaseous state and is a predominant constituent
of foods and drinks, such as fruits and vegetables (around 90% ),
milk (87% ), meat (60-75% ) and dried fruits (20-30% ). Even dried
foods such as cereals, pulses, and other grains also contain
appreciable amounts of water. Water influences the appearance,
texture, and flavor of foods. It is involved in most of the
changes taking place during cooking and processing. It is also
related to the spoilage and deterioration of food by favoring the
growth of undesirable microorganisms. Shelf life of many foods can
be enhanced by keeping the water activity of foods to its minimum.