(1) Properties and uses of malic acid
Food additive malic acid, scientific name. Hydroxysuccinic acid,It is more abundant in apples,It is colorless or slightly yellow knotted wood or pink wood: odorless, with a slightly irritating and refreshing sour taste, and the melting point is128-131 C; easily soluble in water, slightly soluble in alcohol and acyl; highly hygroscopic, easy to store Damp.It10%Aqueous solutionpHValues are2, 4.
The food additive malic acid has a soft sour taste and long persistence. Theoretically, it can replace all or most of the citric acid used in food and beverages. And to achieve the same effect, the dosage of malic acid is 8% to 12% less than that of citric acid. Particularly When used in fruit-flavored foods, carbonated beverages and other foods, geranic acid can effectively improve their fruity flavor.
(2)Production method of malic acid
①Hydration method: First, maleic acid is hydrated to produce maleic acid, which is then hydrated to produce malic acid.
The process flow is shown in Figure 2-15. Dissolve 200kg smoothly in a stainless steel autoclave (1) containing 400kg of steamed water (withstand pressure 1.5MPa) and heat it up to 185+3°C. The pressure is controlled at 1.0MPa and stirred. The addition reaction is about 6~ Stop heating after 8 hours. When cooled to below IDCTC, put the material into the steamer (2). Turn on the vacuum and reduce the pressure to 6OC, 8, OkPa, concentrate, cool and crystallize, filter, and dry to obtain about 200kg of malic acid.
There are many methods for refining DL-malic acid, such as extraction with organic solvents: Germany uses isobutyl acetate or diethyl ketone, acetaminophen, etc. to remove Male and fumaric acid; Japan heats DL-malic acid containing 1-2% maleic acid to 00’C for 2 hours to make the impurities reach trace amounts. France uses target carbon catalytic hydrogenation to make butene The diacid is converted into succinic acid for separation and removal, while the US uses a strong alkaline anion exchange resin for purification.
During the reaction, maleic acid, transbutyric acid enedioic acid and DL-malic acid can form the following equilibrium:
At equilibrium, the ratio of fumaric acid to DL-malic acid is 1:1.7. If fumaric acid is added in proportion during the reaction, Then all the maleic acid is hydrated into DL-malic acid, and the yield increases from 63% to more than 90%.
② Beta method for producing malic acid
Furfural and hydrogen peroxide synthesis method This method uses furfural as raw material, undergoes HQ treatment, and is converted into crystalline DL-malic acid under the action of ultrasonic waves, and at the same time obtains Butenedioic acid,
b. Lactone hydrolysis method. This method uses beta-lactone as raw material, hydrolyzes it at 70 CT for 5 hours, and then treats it with water to obtain 5 final apples. The acid solution is separated by polymer exchange resin and crystallized in acetic acid-benzene to obtain DI malic acid.
C. Fermentation method to produce malic acid, there are two methods: direct fermentation of sugar raw materials and mixed two-step fermentation “with starch , glucose and butenedioic acid are used as raw materials, and are fermented with Brevibacterium flavum, Aspergillus flavus, etc., the sugar conversion rate is 30% ~ 86%, and a product with a purity of more than 98% can be obtained after crystallization.
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