Malic acid, also known as 2-hydroxysuccinic acidAsymmetric carbon atom, there are two stereoisomers.In nature, it exists in three forms, namely D-malic acidL-malic acidAnd its mixtureDL-malic acid It is a white crystal or crystalline powder with strong hygroscopicity, easily soluble in water and ethanol, and has a special pleasant sour taste.Malic acid is mainly used in food and pharmaceutical industries.
Chinese name
malic acid
Foreign name
malic acid
Alias
2-hydroxysuccinic acid
Molecular formula
CfourHsixOfive
molecular weight
one hundred and thirty-four point zero nine
Configuration
Type D (right rotation);L-type (left-handed);DL type (racemic)
There are three isomers of malic acid: L-malic acid, D-malic acid and DL malic acid.The naturally occurring malic acid is L-type, which is found in almost all fruits, with the most in kernel fruits.Malic acid is colorless acicular crystal or white crystal powder, odorless, with irritating, refreshing and sour taste,[1]
(1) D-malic acid[4]
Density: 1.595g/cmthree
Melting point: 98-104 ℃[4]
Boiling point: 306.4 ℃
Flash point: 153.4 ℃
Refractive index: 1.529[4]
Specific rotation:+2.92 ° (methanol)
Solubility: soluble in water, methanol, ethanol and acetone.
(2) L-malic acid[5]
Density: 1.595g/cmthree
Melting point: 101-103 ℃[5]
Boiling point: 306.4 ℃
Flash point: 153.4 ℃
Refractive index: 1.529[5]
Specific rotation: - 2.3 ° (8.5 g/100 ml water)
Solubility: soluble in water, methanol, acetone, dioxane, insoluble in benzene
(3) DL malic acid[6]
The same amount of left and right handed bodies are mixedRacemate。
Density: 1.601
Melting point: 130-132 ℃[6]
Boiling point: 206.4 ℃
Flash point: 153.4 ℃
Refractive index: 1.529[6]
Solubility: soluble in water, methanol, ethanol, dioxane, acetone, insoluble in benzene
The most common is L-malic acid, which is found in the pulp of immature hawthorn, apple and grape fruits.It can also be controlled byFumaric acidIt is produced by biological fermentation.It is an important intermediate product of human internal circulation, easy to be absorbed by human body, so it has excellent performancefood additivesAnd functional food are widely used in food, cosmetics, medical and health products and other fields.Racemes can be prepared by fumaric acid or maleic acid under the action of catalyst under high temperature and pressure and water vapor.
Production method
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The production method of L-malic acid has developed from the early single extraction method to the following methods: extraction, chemical synthesis, one-step fermentation, two-step fermentation, immobilized enzyme or cell transformation.At present, the existing problem is still the lack of excellent production strains. While researching and breeding excellent strains, it is very necessary to pay attention to strengthening the research of extraction technology and other related technologies, and do a good job in the research and development of supporting technologies for upstream and downstream projects.
preparation
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(1) Extraction method: Boil the juice of immature apples, grapes, peaches, etc., add lime water to generate calcium salt precipitation, and then process to generate free malic acid.
(2) Synthesis method: catalytic oxidation of benzene to obtainMaleic acidandFumaric acidAnd then hydrate under high temperature and pressure.Hydration reaction conditions are usually 3-5 h at 180-220'C and 1.4-1.8 MPa.The reaction products are mainly malic acid and a small amount of fumaric acid. Adjust the content of malic acid to 40% at 40 ℃ and cool the solution to about 15'C, filter and separate fumaric acid crystals, concentrate mother liquor, centrifuge and separate solids to obtain crude malic acid, and then refine and crystallize to obtain finished products.
(3) Fermentation method: L-malic acid is produced from fumaric acid by biological enzyme fermentation.[2]
Storage and transportation
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This product is packed in cardboard drums lined with double-layer food grade polyethylene plastic bags. This product is easy to absorb moisture and oxidize. It should be covered during transportation. It should not be mixed with toxic, odor and colored powder. It should be stored in a cool, dry warehouse to avoid the sun.[3]
Application and function
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Food industry application
L-malic acid is an important component of natural fruit juice. Compared with citric acid, L-malic acid has a high acidity (20% stronger than citric acid), but it tastes soft (with a high buffer index), has a special flavor, does not damage the mouth and teeth, is metabolically conducive to the absorption of amino acids, and does not accumulate fat. It is a new generation of food acid,It is praised as the "most ideal food sour agent" by the biological and nutritional circles, and has been replacing citric acid in foods for the elderly and children since 2013.
L-malic acid is an essential organic acid for human body and an ideal food additive with low calorie.When 50% L-malic acid and 20% citric acid are used together, they can present strong natural fruit flavor.
Beverages (various cool drinks): soft drinks prepared with L-malic acid are thirst quenching and refreshing, with malic acid taste, 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 circulating intermediate of biological tricarboxylic acid, which tastes close to natural fruit juice and has a natural flavorcitric acidCompared with, it produces less heat and tastes better, so it is widely used in alcohol, drinks, jam, chewing gum and other foods, and has the tendency to gradually replace citric acid.It is one of the most widely used organic acids in the world food industry and has a good development prospect.
L-malic acid contains natural moisturizing ingredients, which can easily dissolve the "glue" stuck between the dry scaly dead cells, so as to remove the wrinkles on the skin surface and make the skin tender, white, smooth and elastic, so it is popular in cosmetics formulations;L-malic acid can be used to prepare a variety of essences and spices for a variety of daily chemical products, such as toothpaste, shampoo, etc;Compared with citric acid, L-malic acid has a soft and unique sour taste, so it is used abroad to replace citric acid as a new detergent auxiliary to synthesize high-grade special 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 anti-cancer drugs on normal cells;It can also be used to prepare and synthesize insect repellents, anti tartar agents, etc.
Application in pharmaceutical industry
When malic acid is added to various tablets and syrups, it can present fruit flavor, and is conducive to absorption and diffusion in the body. It is often added to compound amino acid injection to improve the utilization rate of amino acids.Its sodium salt is an effective drug for treating liver dysfunction, especially hypertension.Potassium L-malate is a good potassium supplement, which can maintain the water balance of the human body and treat edema, hypertension and fat accumulation.
L-malic acid can be used in pharmaceutical preparations, tablets, syrups, and can also be mixed 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, hypertension, liver failure and other diseases, reduce the toxic effect of anticancer drugs on normal cells, and also be 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, synthetic material plasticizer, feed additive, etc.
Application in daily chemical industry
Zinc L-malate is used in toothpastes as an anti plaque agent, an anti calculus agent, and a synthetic spice formula.
Chemical industry application
It can be used as one of the synthetic materials of scale remover and fluorescent whitening agent.When added to shellac varnish or other varnishes, the paint surface can be prevented from skinning. The polyester resin and alkyd resin produced with this acid are plastics for special purposes.
Agriculture
In November 2022, Chinese scientists will studyIt was found that the selection of organic acids (flavors) such as malic acid was completed in the process of watermelon improvementChoose.[7]
