What is the raw material for the production of citric acid? Urgent!!!

There are two ways to produce citric acid, one is to use starch and sugar as raw materials, such as corn, dried potatoes, rice, rice, taro and even straw to produce by microbial fermentation; In 1891, the German Wehme first discovered that Penicillium could produce citric acid, but it could not be industrialized due to problems such as pollution and fermentation process. In 1916, Thorn in the United States discovered that Aspergillus niger could produce citric acid, and in the same year, Currie used Aspergillus niger to industrialize the production of citric acid by shallow disc fermentation, and established the first factory in Belgium.

A citric acid production process. Using rice as raw material, the rice is ground into rice milk, high-temperature liquid amylase is added, filtered, fermented in seed tanks, filtered, neutralized by adding calcium carbonate, acid adjustment, decolorization, discrossing, concentration, crystallization, and drying to obtain citric acid.

The other is extracted from acid-rich raw materials, especially in fruit processing, such as the salty and sour juice discharged after making plum embryos, the acid content can reach 4-5%, and the salty and sour juices discharged after making citrus embryos are very good raw materials for extracting citric acid. The process is:

1.Clarification and filtration of raw materials: orange juice and plum juice contain a lot of pectin and impurities, which need to be clarified to promote the precipitation of impurities, and then filter with a filter press.

2.Neutralization: It can be neutralized with calcium carbonate or lime, and it should be pre-adjusted into a slurry, and it is best to add 15% calcium carbonate to neutralize.

The specific method is: when the salty and sour water such as orange juice and plum juice is heated to 75 degrees Celsius, calcium carbonate milk slurry is gradually added, and the heating is continued for 2 hours, the initial temperature is controlled at about 5 degrees Celsius, and finally it can be raised to 100 degrees Celsius, and when the solution is blue-green, it means that the neutralization reaction has been completed. Then let it stand to precipitate, and this precipitate is calcium fruit acid (mainly calcium citrate).

3.Salt removal: The obtained calcium citrate contains salt, which can be washed with water, heated to 70-80 degrees Celsius, repeated many times until the salt is removed, and dried for later use.

4.Acid decolorization: calcium citrate slurry is heated to 60-70 degrees Celsius, sulfuric acid with a concentration of 35% is added, boiled for about 3 hours, and the calcium citrate decomposition is completed, that is, it is precipitated statically, and the supernatant is a citric acid solution.

The dark red citric acid is decolorized with 1-2% activated charcoal for half an hour to obtain a colorless clear solution.

5.Concentration and crystallization: The colorless citric acid solution is concentrated to 75% of the solid content, and then crystallized in the crystallization cylinder. Crystallization can be completed in 4-5 days.

6.Centrifugation and drying: citric acid crystals also contain certain water and impurities, which need to be removed by centrifuge. It is then dried at 75 degrees Celsius until the moisture content reaches less than 1%, and finally it is sifted, graded and packaged as the finished product.

There is not much difference between the north and the south in production now, it depends on which raw materials you can easily get and which kind of cost is low!

1. Citric acid is an organic acid with a high yield in the world and is an anhydrous substance. The production process of citric acid mainly includes biological fermentation, fruit extraction and chemical synthesis. Take corn flour.

The production of citric acid as a raw material is conducive to achieving the goals of low energy consumption, low pollution and high efficiency.

After filtration, corn residue and excess protein fermentation process, pressure and sugar mixing ventilation with sterile air for deep fermentation, fermentation tanks to maintain a proper growth temperature 35 37 environment, compared with traditional dried potatoes as raw materials, using corn as a raw material for the production of emerging citric acid and producing acid is fast, the fermentation cycle is short, the cost is low, and the dissolved oxygen capacity is strong. Overall, acid production can be increased by about 10 percent.

2. In order to improve the production process of traditional corn flour fermentation of citric acid to produce dried potatoes as raw materials, through fermentation and calcium salt extraction technology, the product quality produced by this method is poor, the cost is high, and the environmental pollution is serious, in order to further expand the economic benefits, improve the production efficiency, and achieve clean and pollution-free production, it is necessary to improve the extraction process of citric acid production.

3. In terms of raw materials, the corn flour, rice stuffy content and straw in this study, etc., for the ion chromatography of the industrial process, the mother liquor purification treatment and the first waste liquid sugar technology, not only effectively reduce the cost, but also rationally optimize the by-products of citric acid production, and the emission of waste skin and waste waste is conducive to environmental protection.

When corn produces citric acid, only the starch from the corn is used. Other nutrients in corn.

It can be produced**, purified and developed in the production process to produce corn gluten meal, fibre feed and high value-added corn oil.

and other by-products. The production concept of "eat and squeeze" effectively improves the economic benefits.

4. In order to raise the medium.

In the production process, impurities (solids) and excess nutrients in the medium should be removed in time, so that the medium presents a clear liquid state, enhances the dissolved oxygen capacity, and shortens the fermentation cycle.

In addition, after reasonable adjustments, there is no need to add trace elements.

auxin, nitrogen source, inorganic salts.

The medium with the appropriate ratio of various components can greatly improve the conversion rate.

and acid production rate. The use of low-temperature liquefaction technology under normal pressure conditions can not only ensure the quality of the medium, but also meet the requirements of complete liquefaction.

5. When planting corn, mutagenesis breeding methods, selecting suitable corn varieties and mass propagation for the production of citric acid (such as mutant varieties with high starch content), using high-concentration corn flour and high-tech plate acclimation of citric acid, cultivating and selecting high conversion rate, short fermentation cycle speed and high acid strain quality. The application of high-tech methods to the large-scale fermentation process has achieved a double harvest of economic and environmental benefits.

Citric acid is an important organic acid, also known as citric acid, colorless crystal, often containing a molecule of crystal water, odorless, has a strong sour taste, soluble in water. Its calcium salt is more soluble in cold water than in hot water, and this property is often used to identify and isolate citric acid. Anhydrous citric acid can be obtained by controlling the appropriate temperature during crystallization.

It has a very many uses in industry, food industry, cosmetics industry, etc.

Natural citric acid is widely distributed in nature, and natural citric acid is found in the bones, muscles, and blood of plants such as lemons, citrus, pineapples, and other fruits and animals. Synthetic citric acid is prepared by fermentation of sugar-containing substances such as sugar, molasses, starch, grapes, etc., and can be divided into anhydrous and hydrate. Pure citric acid is a colorless transparent crystal or white powder, odorless, with an attractive sour taste.

Many kinds of fruits and vegetables, especially those of the citrus genus, contain high levels of citric acid, especially lemons and limes, which contain a lot of citric acid, which can reach up to 8% after drying (about 47 g l in fruit juice [3]). In citrus fruits, the amount of citric acid is between moll for oranges and grapes and moll for lemons and limes. This content varies with the growth of different cultivars and plants.

Since 1940, when Krebs proposed the theory of the three carboxyl cycles, the fermentation mechanism of citric acid has gradually been recognized. It has been shown that in the biochemical process of producing citric acid from sugar raw materials, the process of converting sugar into pyruvate is the same as that of alcoholic fermentation, that is, it is digested through the E-M pathway (hexose diphosphate pathway). Pyruvate is then further oxidized and decarboxylated to acetyl-CoA, and oxaloacetate produced by carboxylation of acetyl-CoA and pyruvate is condensed to citric acid and enters the tricarboxylic cycle pathway.

Citric acid is an intermediate product in the metabolic process. During the fermentation process, when the activity of aconitate hydratase and isocitrate dehydrogenase in microorganisms is very low, and the activity of citrate synthase is high, it is conducive to the accumulation of large amounts of citric acid.

Sodium citrate, also known as sodium citrate, is an organic compound with white to colorless crystals in appearance. Odorless, cool, salty and spicy. It is stable at room temperature and in air, slightly soluble in humid air, and weathering occurs in hot air.

Heat to 150 degrees to lose crystal water. Soluble in water, soluble in glycerol, insoluble in alcohols and other organic solvents, superthermal decomposition, slightly deliquescent in a humid environment, slightly weathered in hot air, its solution pH value is about 8.

Preparation method: According to the different production raw materials, the preparation methods of sodium citrate mainly include:

Citric acid + sodium hydroxide method.

This is also the earliest production process developed by research and development. Citric acid is dissolved in water, added to sodium hydroxide solution, neutralization reaction occurs and a large amount of heat is generated, and the finished product is obtained by filtration, concentration, crystallization and drying. The process of this method is simple and the product purity is good; The disadvantage is that the production of finished products is high.

It is now only used for the preparation of laboratory supplies.

Citric acid + soda ash method.

Neutralization method improves the process, as a raw material, soda ash is easy to procure, easy to preserve, and has the advantages of low production cost; It is a production method commonly used by various industrial enterprises at present.

Citric acid + baking soda.

This method is an improved preparation method for soda ash products that are not suitable for the pharmaceutical industry. This method uses high-quality baking soda, which is dissolved in water and neutralized with citric acid according to the calculated amount, and processed by concentration and crystallization to prepare pharmaceutical-grade sodium citrate. It is characterized by mild reaction conditions, excellent product quality and good process operability.

At present, this method is mainly used in some pharmaceutical factories.

Calcium citrate + soda ash method.

This method uses calcium citrate mixed with soda ash to meta-decompose to filter out insoluble matter to obtain sodium citrate. The product is of poor purity and the operation process is long. In previous years, it was reported that by adjusting the pH value of the mixing conditions, the process flow was simplified, the production cost was reduced, and a better quality product was obtained.

Recently, sodium citrate has been produced using the resin exchange method. The fermentation liquid was exchanged by ionic resin, and then the adsorbed citric acid was eluted with sodium hydroxide solution, and the sodium salt solution obtained by concentration and crystallization was used to obtain sodium citrate products. This method is pollution-free and low-cost, which is the way that citric acid fermentation manufacturers should develop.

Fermentation process of citric acid.

China is the world's largest producer and exporter of citric acid, and citric acid is currently synthesized.

There are three main methods: fruit extraction, chemical synthesis and microbial fermentation, compared with the other two.

Microbial fermentation method to produce citric acid has a short fermentation cycle, high yield, and is convenient for continuous and control, which is the main production method at present. The fermentation equation is as follows: C12H24O11

Sucrose) + h

2o + 3o2→

2C6H8O7 (citric acid).

The main processes of 4H2O are: strain culture, raw material treatment, inoculation, fermentation, citric acid leaching, acidolysis and decolorization, concentration and crystallization process, and the process flow chart is as follows: Figure 1 Flow chart of citric acid production by fermentation.

figure1

schematic diagram for producing citric acid by fermentation

The process can be briefly described as follows.

First, inoculated with aspergilloin on the culture medium and cultured for fine fermentation.

bacteria, and then inoculate the cultivated bacteria in sterile raw materials, and then send them to the koji chamber for fermentation, and after the fermentation is completed, the koji liquid is put into the soaking tank for soaking, and then the precipitant is added to the fermentation broth.

It is a lime precipitate solution that makes citric acid (c

6H8O7) precipitates to calcium citrate.

ca(c6h

2) After that, sulfuric acid calcium citrate is added to the fermentation broth, and the acid is removed by ion exchange resin.

fe2+，ca

2+ ions, which are then concentrated and crystallized to obtain citric acid. The equation is as follows:

ca(c6h

2+ 3h2so

4→2 c6h8

o7+ caso

4 At this time, a large amount of calcium sulfate precipitation will be produced, which is generally produced for every 1 ton of citric acid produced.

3-4 tons of calcium sulphate waste, which pollutes the environment, which is very undesirable from the point of view of environmental protection and sustainable development, and now there are some new ways to treat the fermentation broth.

This allows for the purpose of crystallizing citric acid, e.g. electrodialysis, by passing the fermentation broth through the negative membrane.

and the positive membrane are alternately combined according to the set order after the electrodialysis desalination chamber, by applying a certain straight.

Flow electric field, after continuous circulation under the action of the pump for a period of time, the citrate in the feed liquid.

It passes through an anion exchange membrane in ionic form and combines with hydrogen ions in a concentrating chamber to form citric acid (the diversion water in the concentrator chamber is deionized water).

So as to achieve the purpose of concentration and purification, and then the concentrate will be concentrated.

Metal ions are removed by cation exchange resin, and then concentrated crystallization to obtain citric acid.

The process is roughly as follows:

Fermentation broth filtration electrodialysis resin exchange concentration crystallization The product can be a combination of microfiltration and ultrafiltration, and if the fermentation broth is pure, ultrafiltration can be directly used.

It has been reported in the literature that the ** rate of citric acid can be achieved after electrodialysis operation.

StandardNO: GB 1987-2007

Chinese standard name standardtitle in Chinese: Food additive Citric acid.

English standard name: food additive - ctric acid

Release Date: 2007-10-29

Date of implementation executedate: June 1, 2008

Firstissuance date: Jul 10, 1980

standardstate: Current.

reviewaffirmance date:

Plan No: 20050815-Q-607

ReplacedStandard: GB 1987-1986

ReplacedStandard:

RevocatoryDate:

adoptedinternational standard no:

adoptedinternational standard name:

adoptedinternational standard:

International Standard Classification (ICS):

Chinese Standard Classification Code (CCS): X42

Standard Category: Product.

Standard page number ofpages:

Standard**(RMB) price( ).

Governor: Standardization Administration of the People's Republic of China.

Focal Unit TechnicalCommittees: National Technical Committee for Standardization of Food Additives.

DraftingCommittee: China Food and Fermentation Industry Research Institute.

Consumption of citric acid (content.

Citric acid, also known as citric acid. The molecular formula is C6H8O7, the molecular weight is widely distributed in plants such as lemons, gooseberries, raspberries and grape juice. Hydrate: 100 hours to melt, density.

Anhydrous: colorless crystals or powders, melting point 153

It has a strong sour taste. Soluble in water, ethanol and ether.

It can be extracted from plant raw materials and can also be prepared by citric acid fermentation of sugar.

It is used in the manufacture of medicines, soft drinks, candies, etc., and can also be used for metal cleaners, mordants, etc., and is an important part of the tricarboxylic acid cycle.

Citric acid is a kind of acidulant, mainly used with food, medicine, chemical sour additives, food use process according to different formulas to add different amounts of citric acid, the addition process is generally in the food main raw material feeding stage.