Malic acid has three isomers: L-malic acid, D-malic acid and DL-malic acid. Naturally occurring malic acid is L-shaped, and it is present in almost all fruits, with the most in pome fruit. Malic acid is a colorless needle-like crystal or a white crystal powder, odorless, with a pungent and refreshing sour taste, melting point 127-130℃, easily soluble in water, 55.59/100mL (20℃), soluble in ethanol, insoluble In ether. It is hygroscopic, and the pH value of 1% (mass) aqueous solution is 2.4.
Food industry applications
L-malic acid is an important component of natural fruit juice. Compared with citric acid, it has high acidity (the acidity is 20% stronger than citric acid), but it tastes soft (has a higher buffer index), has a special fragrance, and does not damage the mouth and teeth. It is metabolically beneficial to the absorption of amino acids and does not accumulate fat. It is a new generation of food soursing agents. It is hailed as "the most ideal food soursing agent" by the biological and nutritional circles. It has been replacing citric acid in food for the elderly and children since 2013. .
L-malic acid is an organic acid necessary for the human body and an ideal food additive for low calories. When 50% L-malic acid is used with 20% citric acid, it can present a strong natural fruit flavor.
Beverages (various refreshing drinks): Soft drinks prepared with L-malic acid are thirst-quenching and refreshing, with a sour taste of apple, close to natural fruit juice. Some large domestic food companies, 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. The taste is close to natural fruit juice and has natural flavor. Compared with citric acid, it produces lower calories and better taste. Therefore, it is widely used in wines, beverages and jams. , Chewing gum and other foods, and gradually replace 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 emollient ingredients, which can easily dissolve the "stickies" stuck between dry and scaly dead cells, which can remove wrinkles on the skin surface and make the skin white and smooth But it is elastic, so it is favored in cosmetic formulations; L-malic acid can be used to formulate a variety of flavors and spices, and used in a variety of daily chemical products, such as toothpaste, shampoo, etc.; compared with citric acid, L-malic acid Malic acid has a soft and unique sour taste, so it is used abroad as a new type of detergent as a substitute for citric acid to synthesize high-end specialty detergents.
L-malic acid can be used to treat liver disease, anemia, low immunity, uremia, hypertension, liver failure and other diseases, and can reduce the toxic effect of anticancer drugs on normal cells; it can also be used for preparation and synthesis of anthelmintics Agent, anti-tartar agent, etc.
Function 1: Sour taste regulator
The taste of L-malic acid is close to the sour taste of natural apples. Compared with citric acid, it has the characteristics of large acidity, soft taste, and long residence time. It has been widely used in high-end beverages, food and other industries, and has become the consumption after citric acid and lactic acid. The third food sour agent. The beverage prepared with L-malic acid is more sour, sweet and delicious, close to the flavor of natural juice. The combination of malic acid and citric acid can mimic the sour taste of natural fruits, making the taste more natural, harmonious and plump. Malic acid can be added to soft drinks, powdered drinks, lactic acid drinks, milk drinks and fruit juice drinks to improve their taste and flavor. Malic acid is often used in conjunction with the synthetic dipeptide sweetener ASPARTME as a soft drink The flavor fixative is added. 100 grams of malic acid is almost 1.25 times stronger than adding 100 grams of citric acid, or 80 grams of malic acid and 100 grams of citric acid form the same sourness intensity, so to achieve the same sourness intensity, using L-malic acid can reduce The dosage is 20%. For some foods, adding malic acid can save 10%-20% of white sugar. Because its sour taste is better than citric acid, and the US FDA (Food and Drug Administration) has restricted the use of citric acid in children and elderly foods. Therefore, the application of L-malic acid in the food industry has gradually replaced citric acid in recent years.
Fermentation
L-malic acid is an intermediate in the tricarboxylic acid cycle of organisms, can participate in the fermentation process of microorganisms, and can be used as a carbon source for the growth of microorganisms, so it can be used as a food starter. For example, it can be used as a yeast growth promoter, or it can be added to fermented milk.
Gelation
When there is a certain amount of pectin and sugar, acid is the key condition for gel formation. To prevent flocculation and coagulation in the production of concentrated fruit juice, it is necessary to control the conditions of coagulation caused by pectin. Therefore, L-malic acid can make pectin gel, so it can be used to make fruit cakes, jelly gel jams and fruit purees.
Function 2: Preservative
Malic acid can be widely used as a food preservative. Microorganisms need to grow and reproduce normally in a certain pH environment. If the pH value in the environment is not suitable, it may affect the charged properties of the cell surface, thereby causing changes in membrane permeability and affecting normal cell metabolism. The effect of acids on microorganisms is not only proportional to the concentration of hydrogen ions, but also related to the antioxidant effects of organic acids, acid anions and unionized molecules. Malic acid ionizes under neutral conditions but not under acidic conditions. Ionization, but the bactericidal ability under acidic conditions is more than 100 times greater than that under neutral conditions, mainly because molecular organic acids are more likely to penetrate cell membranes, while ionic acids cannot easily penetrate cells. In addition, it can also promote the thermal denaturation of proteins.
Inhibit enzymatic browning
Cutting vegetables is a new type of vegetable processing product that has emerged from abroad. Because of its convenience and quickness, it is increasingly favored by people. Especially in the United States, it is estimated that by 2005, cut vegetables will account for 30% of the total sales in the US retail market. Potato is an important economic crop in my country, and its browning has attracted people's attention. Malic acid can lower the pH value and produce chelation to inhibit the activity of phenol oxygenase and prevent browning. In addition, it also inhibits other causes of browning.
Function 3: In addition to fishy deodorant
Used as a deodorant, it can remove fishy, body odor and food storage. Adding L-malic acid to milk can also improve the quality.
Function 4: Pasta Enhancer
L-malic acid has a strengthening effect on pasta. It can increase the disulfide groups in the gluten protein, increase the protein molecules, form a macromolecular network structure, and enhance the air permeability, elasticity and toughness of the dough. In addition, the flour contains cysteine and cystine, they are protease activators, L-malic acid can make them lose their ability to activate the protease and prevent the protease from decomposing the protein in the flour. In addition, flour can be bleached to improve the binding effect of protein.
Function five: salt reduction effect
L-malic acid can be used to make salty foods and reduce the amount of salt. For example, sodium malate has moderate saltiness and can often be used to make salty foods. Malic acid can form many derivatives. In Japan, malate has been successfully used in sugar-reduced and salt-reduced foods in recent years. When some salts of malic acid are used instead of salt to immerse pickles, the salty taste is only salt 1/ In the case of 5-1/7, the macerating effect is twice that of table salt. At the same time, it can be used as a salt substitute for patients with nephritis. The addition of calcium malate to soy milk can effectively improve its taste and flavor.
Function 6: protect vitamin C, color retention
The color tone of the pigments contained in fruits and vegetables is often affected by the acidity and alkalinity. In some discoloration reactions, acid is often an important component. For example, chlorophyll will turn into yellow-brown pheophytin under acidic conditions. When the anthocyanin changes from acid to neutral, it will gradually change from red to purple. Tannins will form pink "red powder" under acidic conditions. Wait. Therefore, L-malic acid can be used as a color retention agent for some foods, such as a natural sherbet color retention agent.
Function 7: Anti-oxidation, inhibit oil rancidity
L-malic acid has good antioxidant capacity. The oxidation of lipids in food can cause rancidity, protein destruction and pigment oxidation, which will reduce the sensory properties of the food, reduce the nutritional value, and shorten the shelf life. Adding food antioxidants can delay oxidation, extend shelf life, and maintain the color, flavor and nutritional value of food.
Pharmaceutical industry application
Malate Shuttle System
Adding malic acid in various tablets and syrups can present a fruity taste and is beneficial to absorption and diffusion in the body. It is often mixed into compound amino acid injections to improve the utilization of amino acids. Its sodium salt is an effective drug for treating liver insufficiency, especially hypertension. L-potassium malate is a good potassium supplement. It can maintain the body's water balance and treat edema, high blood pressure and fat accumulation.
L-malic acid can be used in pharmaceutical preparations, tablets, syrups, and can also be formulated into amino acid solutions, which can significantly improve the absorption rate of amino acids; L-apple can be used to treat liver disease, anemia, low immunity, uremia, and hypertension. Blood pressure, liver failure and many other diseases, and can reduce the toxic effect of anti-cancer drugs on normal cells, and also used to prepare and synthesize insect repellents, anti-tartar agents, etc. In addition, L-malic acid can also be used as industrial cleaning agent, resin curing agent, plasticizer for synthetic materials, feed additive, etc.
