Water makes possible a vast number of chemical reactions that are important in foods. These include ionization, pH changes, salt formation, hydrolysis, and the release of carbon dioxide.
When particles dissolve in a solvent, the solution is either molecular or ionic in nature. Molecular solutions are those in which the dissolved particles remain “as is” in their molecular form. An example would be the dissolving of a flavored sugar mix in water to make a beverage. The sugar molecules remain unchanged in solution. Ionic solutions occur when the solute molecules ionize into electrically charged ions or electrolytes. When salt, or sodium chloride (NaC1), is dissolved in water, it ionizes into the individual ions of sodium (Na’) and chloride (CI-).
This chemical reaction is written: NaC1 —> Na. + Cl-
pH—Acids and Bases. Acids are substances that donate hydrogen (H+) ions, and bases provide hydroxide (OH-) ions. Another defining difference between acids and bases is that acids are proton donors, while bases are proton receptors. The pH scale (“pH” stands for “power” and “hydrogen”) is a numerical representation of the hydrogen (H+) ion concentration in a liquid. A solution with a pH of under 7 is considered acidic, while anything over 7 is alkaline or basic. A pH of 7 indicates that the solution is neutral, containing equal concentrations of hydrogen (H+) ions and hydroxyl (OH-) ions. Each number on the scale represents a tenfold change in degree of acidity.
Water is naturally neutral, but tap water is normally adjusted to be slightly alkaline (pH 7.5 to 8.5), because acidic water causes pipe corrosion. Overly alkaline water, however, results in deposits of carbonates that may block water pipes. Many coffee connoisseurs prefer distilled water for making coffee because of its neutral nature.
The universal solvent of water makes it possible to form salts, which occurs when a positive ion combines with a negative ion, as long as it is neither a hydrogen (H.) or hydroxide (OH-) ion. The primary example is sodium chloride (Na.C1-) resulting from sodium (Na`) combining with chloride (Cll. Salts can also be formed by combining an acid and base, or a metal and a nonmetal. Metal salts include potassium fluoride (K+F–) and lithium bromide (Li+Br).
Countless chemical reactions rely on hydrolysis. Just a few of the hydrolysis applications used in the food industry include breaking down cornstarch to yield corn syrup, dividing table sugar into its smaller components to create another sugar helpful in the manufacture of some candies, and creating protein hydrosylates, smaller molecules derived from protein hydrolysis, to add to foods to improve flavor, texture, foaming abilities, and nutrient content.
Carbon Dioxide Release
Many baked products are allowed to rise before baking. One of the agents making this possible is baking powder, which is a combination of baking soda and acid. It is only when baking powder is combined with water that the gas carbon dioxide is released, which causes baked products to rise. The chemical reaction is a two-step process:
N.1-1c03 eater NAY:. H,CO3
baking soda + acid –> salt + carbonic acid
H2CO3 > H20 + CO2
carbonic acid -> water + carbon dioxide