Water is abundant in all living things and consequently, in almost all foods, unless steps have been taken to remove it. It is essential, even though it contributes no calories to the diet.
Water also greatly affects the texture of foods, as can be seen when comparing grapes and raisins (dried grapes), or fresh and wilted lettuce.
It gives crisp texture or turgor to fruits and vegetables, and it also affects perception of the tenderness of meat.
For some food products, such as potato chips, salt, or sugar ,lack of water is an important aspect of their quality, and keeping water out of such foods is important to maintain quality.
Almost all food processing techniques involves the use of water or modification of water in some form: freezing, drying, emulsification (trapping water in droplets), breadmaking, thickening of starch, and making pectin gels are a few examples.
Further, because bacteria cannot grow without water, the water content has a significant effect on maintaining quality of the food.
This explains why freezing, dehydration, or concentration of foods increases shelf life and inhibits bacterial growth.
Water is important as a solvent or dispersing medium, dissolving small molecules to form true solutions and dispersing larger molecules to form colloidal solutions.
Acids and bases ionize in water; water also necessary for many enzyme-catalyzed and chemical reactions to occur, including hydrolysis of compounds such as sugars. It is important as a heating and cooling medium and as a cleansing agent.
Water in Food
