Malic acid

Malic acid, also known as 2-hydroxybutanedioic acid, has two stereoisomers due to the presence of an asymmetric carbon atom in its molecule. In nature, it exists in three forms: D-malic acid, L-malic acid, and their mixture DL-malic acid. (1) D-Malic acid: Density 1.595, melting point 101°C, decomposition point 140°C, specific optical rotation +2.92° (in methanol); soluble in water, methanol, ethanol, and propanone. (2) L-Malic acid: Density 1.595, melting point 100°C, decomposition point 140°C, specific optical rotation -2.3° (8.5 g/100 ml of water); soluble in water, methanol, propanol, and dioxane, insoluble in benzene. An equal mixture of the levorotatory and dextrorotatory forms yields a racemate. Density 1.601 ； Melting point 131-132°C, decomposition point 150℃ ； Soluble in water, methanol, ethanol, dioxane, and propane; insoluble in benzene. The most common one is the levorotatory form, L-malic acid, which is found in the juices of unripe hawthorn, apple, and grape fruits. It can also be produced through biological fermentation of fumaric acid. It is an important intermediate product in the body’s internal circulation and is easily absorbed by the human body; therefore, as a high-performance food additive and functional food, it is widely used in fields such as food, cosmetics, medicine, and health products. The racemate can be obtained from fumaric acid or maleic acid under high temperature and pressure in the presence of a catalyst and water vapor. 　　L-malic acid is an intermediate in the tricarboxylic acid cycle in organisms. It has a taste similar to that of natural fruit juices and possesses a natural aroma. Compared to citric acid, it produces fewer calories and offers a better taste, which is why it is widely used in various foods such as alcoholic beverages, drinks, jams, and chewing gum, and it is gradually replacing citric acid. It is one of the organic acids with the highest usage and the best prospects for development in the global food industry at present. 　　L-malic acid contains natural moisturizing ingredients that can easily dissolve the \"adhesives\" sticking between dry, scaly dead cells, thereby removing wrinkles from the skin surface and making the skin softer, fairer, smoother, and more elastic; for this reason it is highly favored in cosmetic formulations ； L-malic acid can be used to formulate various flavors and fragrances, which are applied in a range of daily chemical products such as toothpaste and shampoo ； Compared to citric acid, L-malic acid has a milder and distinct sour taste; for this reason, it is used abroad as a substitute for citric acid in the production of new types of detergent additives for high-end specialty detergents. L-malic acid can be used in pharmaceutical formulations, tablets, and syrups; it can also be added to amino acid solutions, thereby significantly improving the absorption rate of those amino acids ； L-malic acid can be used to treat various diseases such as liver disease, anemia, low immunity, uremia, hypertension, and liver failure, and it can reduce the toxic effects of anticancer drugs on normal cells ； It can also be used to prepare and synthesize insecticides, anti-tartar agents, etc. Additionally, L-malic acid can also be used as an industrial cleaning agent, a resin curing agent, a plasticizer for synthetic materials, and a feed additive. III. Applications and Functions of Malic Acid 3.1 Applications of Malic Acid in the Food Industry L-malic acid is an important component of natural juices. Compared to citric acid, it has a higher acidity level (its sourness is 20% stronger than that of citric acid), but its taste is milder (it has a higher buffer index). It also possesses a distinctive aroma, does not damage the mouth or teeth, facilitates the absorption of amino acids during metabolism, and does not lead to fat accumulation. As a new generation of food acidulant, it is regarded by the biological and nutritional communities as \"the most ideal food acidulant.\" ”It is currently replacing citric acid in foods for the elderly and children. L-malic acid is an organic acid essential for the human body, and it is also an ideal low-calorie food additive. When 50% L-malic acid is used together with 20% citric acid, it can produce a strong flavor reminiscent of natural fruits. Beverages (various refreshing drinks): Soft drinks prepared with L-malic acid are thirst-quenching and tasty, with a malic acid flavor that is similar to that of natural fruit juices. Some large domestic food companies, such as Wahaha Group and Jianlibao Group, have begun using L-malic acid in their beverages. Candies, jams (mayonnaise), and jellies; margarine; alcoholic beverages (liqueurs); chewing gum. 3.2 Applications of malic acid in the pharmaceutical industry: Adding malic acid to various tablets and syrups gives them a fruity flavor and facilitates their absorption and distribution in the body. It is often included in mixed amino acid injections to improve the utilization rate of those amino acids. Its sodium salt is an effective drug for treating hepatic insufficiency, especially hypertension. L—Potassium malate is an excellent source of potassium; it helps maintain the body’s water balance and can be used to treat conditions such as edema, high blood pressure, and fat accumulation. L-malic acid can be used in pharmaceutical formulations, tablets, and syrups; it can also be added to amino acid solutions, thereby significantly improving the absorption rate of those amino acids ； L-apple can be used to treat various diseases such as liver disease, anemia, low immunity, uremia, hypertension, and liver failure; it can also reduce the toxic effects of anticancer drugs on normal cells. Additionally, it is used in the preparation and synthesis of anthelmintics, anti-tartar agents, and other products. Additionally, L-malic acid can also be used as an industrial cleaning agent, a resin curing agent, a plasticizer for synthetic materials, and a feed additive. 3.3 Applications of malic acid in the cosmetics industry: Zinc L-malicate is used in toothpaste as an agent to prevent plaque formation and tartar buildup, as well as in synthetic fragrance formulations. 3.4 Applications of malic acid in the chemical industry: It can be used as a descaling agent and as one of the raw materials for the synthesis of fluorescent brighteners. Added to shellac varnishes or other varnishes, it prevents the formation of a crust on the paint surface. The polyester resins and alkyd resins produced using this acid are plastics with special applications. 3.5 Health benefits of malic acid Biological macromolecules are the foundation of all forms of life, and there are four important types of biological macromolecules: proteins, nucleic acids, polysaccharides, and lipids. And the most fundamental condition for them to possess physiological activity is that they should have a certain spatial conformation. For example, all 20 amino acids that make up proteins are of the L-type, because if D-amino acids were present in the long chains that constitute proteins, it would prevent the formation of their tight spatial structures. Similarly, other macromolecules should also follow this rule; they are generally of left-handed structure. L-malic acid is an important intermediate in the citric acid cycle in the human body. Since there is only L-malate dehydrogenase in the human body, both from a structural perspective and considering the actual physiological conditions, L-malic acid must be utilized. This is also why some developed Western countries prefer L-malic acid; for example, the United States has stipulated that DL-malic acid must not be used in infant foods, beverages, and medications, and instead L-malic acid must be used. In terms of the role of food in sustaining life, it is essentially involved in metabolic and energy conversion processes; proteins, lipids, carbohydrates, and so on all go through the citric acid cycle, which is the final and most important step in this conversion process. It plays a key role in ensuring that the body’s physiological functions operate properly. In this way, we integrate food and health organically. The health benefits of malic acid lie in preventing abnormal functioning of the citric acid cycle in the body due to a lack of L-malic acid, which could lead to metabolic disorders. L-malic acid possesses physiological activity and is widely present in organisms, although its amount varies from person to person. As the saying goes, \"food and medicine share the same origin.\" The health benefits of L-malic acid and related products in dietary therapy are as follows: A. Due to its special role in the metabolic pathways of the body, malic acid can directly participate in human metabolism and be absorbed by the body, thereby providing energy to the body in a short time and helping to reduce fatigue. It has anti-fatigue effects and helps to restore physical strength quickly. Utilizing the anti-fatigue properties of malic acid, as well as its benefits for protecting the liver, kidneys, and heart, it is possible to develop health drinks. 　B. The normal functioning of metabolism enables the proper breakdown of various nutrients, facilitating their absorption and metabolism in the body. With low calories, it can effectively prevent obesity and help with weight loss. 　C. Adding malic acid to drugs can increase their stability and facilitate their absorption and diffusion in the human body ； In the production of compound amino acid infusions, L-malic acid is utilized for its ability to regulate pH levels. As one of the components of mixed amino acid infusions, it helps improve the utilization rate of amino acids. It is used in the treatment of uremia, hypertension, etc., and helps reduce the damage caused by anticancer drugs to normal cells. It serves as an adjuvant therapy after cancer radiotherapy and chemotherapy, and can also promote wound healing in cases of burns. 　D, L-malic acid can promote ammonia metabolism, reduce blood ammonia levels, and provide protection for the liver; it is an effective treatment for hepatic insufficiency, liver failure, and liver cancer, especially for hyperammonemia caused by liver dysfunction. 　E, L—Malic acid, as one of the components of the basic solution used in the treatment of heart diseases, is employed to supplement K+ and Mg2+, maintain the energy metabolism of the myocardium, and provide protection for the ischemic myocardial layers in cases of myocardial infarction. 　F, L—Malic acid is a stabilizer for calcium lactate injection solutions; it can also serve as a precursor for anticancer drugs and as a promoter of animal growth. 　G. Anti-tartar effect: Malic acid has a high acidity level, a mild taste, a unique aroma, and its corrosive effect is relatively weak; as a result, less wear occurs to the enamel, and it does not cause damage to the mouth or teeth. 　H. It can improve the energy metabolism of brain tissue and regulate neurotransmitters in the brain, which is beneficial for the recovery of learning and memory functions; it has a significant positive effect on learning and memory.
I. Melatonin (MT) is an indole hormone primarily secreted by the pineal gland, and it possesses various biological activities. Since its synthetic production and launch as a health food, there has been a surge in research both domestically and internationally. Numerous animal experiments and clinical studies have shown that melatonin has good sedative and hypnotic effects. L-malic acid is a relatively ideal inhibitor of glutamate decarboxylase. The hypnotic effect of melatonin is related to glutamate decarboxylase, and L-malic acid may reduce sleep and increase excitability. 　J, L—Malic acid provides protection for human vascular endothelial cells and resists the effects on damaged endothelial cells. 　K and CCM are ideal calcium supplements with high biological activity; they can effectively replenish calcium. When other nutrients are adequately supplied, using CCM as a calcium source in feed can ensure and promote the growth and development of small animals. Acid taste regulator: L-malic acid has a taste similar to that of natural apples. Compared with citric acid, it features higher acidity, a milder flavor, and a longer lasting effect. It is now widely used in industries such as high-end beverages and food products, and has become the third most commonly used food acidulant after citric acid and lactic acid. Beverages prepared with L-malic acid are more sour and sweet, with a flavor close to that of natural fruit juice. The combined use of malic acid and citric acid can mimic the acidic characteristics of natural fruits, resulting in a more natural, balanced, and rich taste. Malic acid can be added to soft drinks, powdered beverages, lactic acid beverages, dairy beverages, and fruit juice beverages to improve their taste and flavor. It is often used in combination with the synthetically produced dipeptide sweetener aspartame (ASPARTAME) as a flavor stabilizer in soft drinks. 100 grams of malic acid is almost 1.25 times more effective than 100 grams of citric acid; in other words, 80 grams of malic acid has a similar level of acidity to 100 grams of citric acid. Therefore, using L-malic acid allows for a 20% reduction in the amount needed to achieve the same level of acidity. In some foods, the use of malic acid can help save 10% to 20% of the sugar required. Since its acidic effect is stronger than that of citric acid, and the U.S. FDA has restricted the use of citric acid in foods intended for children and the elderly, L-malic acid has gradually come to replace citric acid in the food industry over the past few years. Fermentation L-malic acid is an intermediate in the tricarboxylic acid cycle of organisms; it can participate in the fermentation processes of microorganisms and serve as a carbon source for their growth, which makes it suitable for use as a food fermenting agent. For example, it can be used as a promoter for yeast growth, or it can be added to fermented milk. There are many more, but knowing the above is sufficient.