There are three isomers of malic acid: L- malic acid, D- malic acid and DL- malic acid. Naturally occurring malic acid is L-shaped and exists in almost all fruits, especially nut fruits. Malic acid is colorless needle crystal or white crystal powder, odorless, with pungent and refreshing sour taste, melting point 127- 130℃, easily soluble in water, 55.59/ 100 ml (20℃), soluble in ethanol and insoluble in ether. It has hygroscopicity, and the pH value of 1% (mass) aqueous solution is 2.4.
L- malic acid is an important component of natural fruit juice. Compared with citric acid, L- malic acid has a higher acidity (acidity is 20% stronger than citric acid), but it has a soft taste (higher buffer index), a special flavor, no harm to the mouth and teeth, and its metabolism is beneficial to the absorption of amino acids without accumulating fat. It is a new generation of food souring agent, and is praised as "the most ideal food souring agent" by biology and nutrition circles. Since 20 13, it is replacing citric acid in food for the elderly and children.
L- malic acid is an essential organic acid for human body and an ideal food additive with low calorie. When using 50% L- malic acid and 20% citric acid, it can present a strong natural fruit flavor.
Drinks (all kinds of cool drinks): soft drinks made of L- malic acid are dry, cool and refreshing, with apple sour taste, close to natural juice. Some large domestic food enterprises, such as Wahaha Group and Jianlibao Group, began to use L- malic acid in beverages.
L- malic acid is a cyclic intermediate of biological tricarboxylic acid. Its taste is close to that of natural fruit juice, and it has a natural fragrance. Compared with citric acid, L- malic acid produces less calories and tastes better. Therefore, it is widely used in wine, beverage, jam, chewing gum and other foods, and has the momentum of gradually replacing citric acid. It is one of the organic acids with the largest consumption and good development prospects in the world food industry.
L- malic acid contains natural moisturizing ingredients, which can easily dissolve the "stickies" stuck between dry squamous dead cells, thus removing wrinkles on the skin surface and making the skin white, smooth and elastic, so it is favored in cosmetic formulations. L- malic acid can be used to prepare flavors and fragrances of various daily chemical products, such as toothpaste and shampoo. Compared with citric acid, L- malic acid has a soft and unique sour taste, so it is used to replace citric acid as a new washing aid abroad and to synthesize advanced special detergents.
L- malic acid can be used to treat liver diseases, anemia, hypoimmunity, uremia, hypertension, liver failure and other diseases, and can reduce the toxic effect of anticancer drugs on normal cells; It can also be used to prepare and synthesize insect repellent, anticalculus agent, etc.