Potassium sorbate is the potassium salt of sorbic acid and is a white crystalline powder at room temperature. It's primarily used as a food preservative and is also found in personal care products. Potassium sorbate is generally regarded as safe and effective for these purposes and has approximately the same toxicity as table salt.
Structure
Potassium sorbate has the molecular formula C6H7O2K although the formula (CH3)(CH)4COOK shows its structure more clearly. The first carbon atom on one end has three hydrogen atoms. The next four carbon atoms have one hydrogen atom, a single bond with one of the adjoining carbon atoms and a double bond with the other adjoining carbon atom. The carbon atom on the other end of the potassium sorbate molecule has a double bond with an oxygen atom and a single bond with the remaining oxygen atom. This oxygen atom also shares an ionic bond with the potassium atom.
Production
Potassium sorbate is produced commercially by reacting sorbic acid (C6H8O2) with potassium hydroxide (KOH) to produce potassium sorbate and water. The following equation shows this reaction: C6H8O2 + KOH -> C6H7O2K + H2O. This reaction simply exchanges the hydrogen atom in the hydroxide (OH-) ion of sorbic acid with the potassium ion in potassium hydroxide.
Properties
Potassium sorbate has a molar mass of 150.22 grams per mole and a density of 1.363 g per cubic centimeter. It decomposes at 270 degrees Celsius. It has a solubility of 58.2 percent in water at 20 degrees Celsius. Potassium sorbate is also soluble in ethanol and propylene glycol, and slightly soluble in acetone.
Food Preservative
Potassium sorbate is effective in inhibiting the growth of many yeasts and molds in foods. It's commonly added to dried fruits and meats, cheeses, yogurt and baked goods. Potassium sorbate is also routinely added to dietary supplements and personal care products to increase their shelf life.
Wine Stabilizer
Potassium sorbate is also added to wine when the winemaker wishes to prevent any fermentation. This is usually done when the wine is put into bottles to stabilize the wine at its current alcohol content. It's especially important to stabilize the wine when sweetening it prior to bottling to keep the fermentation process from restarting.
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