Potassium malate is the potassium salt of malic acid and has the formula K2(C2H4O(COO)2). It is a colorless crystalline powder and is easily soluble in water. It is widely known by its E number E351. Potassium malate is used in the food industry as flavouring agent, as an antioxidant and as acidity regulator. It is an important compound in the transport of nitrate from the roots of a plant to the leaves of the plant. Potassium malate is the salt that transports from the leaves to the root. At the root the potassium maleate oxidizes to potassium carbonate, then is converted to potassium nitrate by soil nitrate and transported back to the leaves.
The reaction of maleic acid with a hydroxide of potassium is carried out. In general this reaction is conducted by admixing maleic acid with an excess of the hydroxide in the presence of water. The reaction mixture is then heated for from about one day to about one month at temperatures ranging from about 50° C. to reflux temperatures. Naturally, the temperature range and time intervals employed may be reduced if this reaction is conducted under pressure.
Potassium malate is widely used as flavouring agent and as acidity regulator in the food industry. It is added to beverages, drinks, meats, desserts, confectionaries etc. It also helps to prolong the shelf life of the processed food by acting as flavouring acid and pH regulator.
Potassium malate serves as an effective humectant. It is widely used in creams, lotions, soaps etc. It helps in keeping our skin moist ad healthy.