Industrial production method of organic DHA oil

Abstract

The invention discloses an industrial production method of organic DHA oil, and belongs to the technical field of oil nutrition products. The method replaces non-organic nitrogen sources and expensive organic nitrogen sources with organic soybean meal enzymatic hydrolysate, selects an organic carbon source, eliminates the use of non-organic auxiliary materials such as vitamins, and realizes low-cost industrial production of organic DHA oil through seed culture and fermentation culture. The invention pre-treats the soybean meal by adding citric acid before enzymatic hydrolysis, which not only makes the enzymatic hydrolysis more sufficient, but also shortens the enzymatic hydrolysis time by at least 12 hours, and the industrial production energy consumption is lower, which greatly reduces the production cost, and realizes the industrial low-cost production of organic DHA oil.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and fat nutritional products, and in particular relates to an industrial production method of organic docosahexaenoic acid (DHA) oil. Background Art

[0002] Docosahexaenoic acid (DHA) is an important ω-3 polyunsaturated fatty acid that cannot be synthesized by the human body. It is an important component of the brain development and retina of infants and young children. It promotes the intellectual and visual development of infants and young children. It also has a series of physiological functions for the elderly, such as softening blood vessels, lowering cholesterol, and regulating blood cells. Its nutritional value and commercial significance are becoming increasingly significant.

[0003] At present, with the rapid development of global organic agriculture and organic nutrition product processing industries, the demand for organic DHA oil products is also increasing. DHA oils are mainly derived from deep-sea fish oil and microbial fermentation. Due to various pollutions faced by the ocean in recent years, all deep-sea fish oil DHA cannot meet the processing conditions of organic products. Another source is microbial fermentation of fish oil. This method can theoretically meet the regulatory requirements of organic products, but in the actual production process, it is impossible to buy cheap organic nitrogen sources suitable for industrial production. The non-organic nitrogen sources used in traditional fermentation, such as yeast extract, are sold at a market price of 18,000 yuan / ton, while the market price of organic yeast extract is 200,000 to 300,000 yuan / ton, and it is difficult to buy pure organic yeast extract on the market, which brings great difficulties to the fermentation of organic DHA oil, resulting in the inability of related companies to carry out large-scale industrial production. In order to reduce production costs, Chinese patent CN104212846A discloses a method for fermenting Schizochytrium to produce DHA using cheap soybean meal as a nitrogen source. However, this technology uses non-organic raw and auxiliary materials such as sodium glutamate and vitamins, resulting in the resulting products not complying with organic regulations and cannot be sold as "organic food". In addition, the soybean meal hydrolysis method involved in this technology takes a long time and the hydrolysis is not sufficient, resulting in complicated subsequent processing steps for the obtained nitrogen source and high production costs.

[0004] Due to regulatory restrictions on organic product processing, organic DHA oils cannot be produced industrially or the production costs are extremely high. Therefore, it is urgent to develop a new low-cost industrial production process. Summary of the invention

[0005] In view of the shortcomings of the prior art and the limitations of relevant regulatory requirements, the purpose of the present invention is to provide an industrial production method of docosahexaenoic acid (DHA) oil with simple operating steps, low production cost and full compliance with organic agricultural processing regulations.

[0006] In order to achieve the above technical objectives, the inventors conducted a large number of experimental studies and made unremitting efforts. Finally, they replaced non-organic nitrogen sources and expensive organic nitrogen sources with organic soybean meal enzymatic hydrolysate, selected organic carbon sources, eliminated the use of non-organic auxiliary materials such as vitamins, and realized low-cost industrial production of organic DHA oils through seed culture and fermentation culture.

[0007] Specifically, the object of the present invention is achieved by providing an industrial production method of organic DHA oil, the method comprising the following steps:

[0008] (1) Preparation of nitrogen source: grind the organic soybean meal raw material and add water to prepare a dispersion, adjust the pH to 2.9-3.1 with citric acid solution, heat to 80-85° C., keep warm in a water bath for 40-60 min, then cool to 50-55° C., adjust the pH to 7-8, add papain, and hydrolyze at 50-55° C. for 10-12 h to obtain soybean meal hydrolyzate for later use;

[0009] (2) preparing a culture medium: preparing a seed culture medium and a fermentation culture medium for Schizochytrium, wherein the nitrogen source in the seed culture medium and the fermentation culture medium is the soybean meal hydrolyzate prepared in step (1);

[0010] (3) Seed culture: The seed solution of Schizochytrium schizochytrium was transferred to a seed tank containing seed culture medium through a sterile inoculation port at an inoculation rate of 1 to 10% by volume and cultured for 3 to 5 days. During the seed culture, the pH of the culture medium was controlled at 4.0 to 6.0, the stirring speed was 100 to 120 rpm, and the ventilation volume was 0.3 to 0.5 m 3 / h, the culture temperature is 26-28℃;

[0011] (4) Fermentation culture: The inoculum was transferred at a volume ratio of 10 to 15%, and the inoculum was transferred to a fermentation tank containing a fermentation medium through a sterile inoculation port and cultured for 4 to 6 days. During the fermentation culture, the pH of the medium was controlled at 6.0 to 7.5, the stirring speed was 200 to 300 rpm, and the ventilation volume was 0.5 to 1.0 m 3 / h, the culture temperature is 26-28℃.

[0012] It should be noted that the key to the present invention is that chemical synthetic additives and vitamin substances that do not meet regulatory requirements are not used, and conventional non-organic nitrogen sources are replaced by organic soybean meal hydrolysate. In addition, the utilization rate of the organic nitrogen source (soybean meal hydrolysate) provided by the method completely exceeds the utilization rate of non-organic nitrogen sources.

[0013] Further preferably, in the industrial production method of organic DHA oil as described above, in step (1), the particle size of the organic soybean meal raw material after pulverization is less than 20 mesh.

[0014] Further preferably, in the industrial production method of organic DHA oil as described above, the dispersion in step (1) is prepared by mixing the organic soybean meal raw material and water in a mass ratio of 1:(4-6).

[0015] Further preferably, in the above-mentioned industrial production method of organic DHA oil, the mass fraction of the citric acid solution in step (1) is 5-15%.

[0016] Further preferably, in the industrial production method of organic DHA oil as described above, the dosage of papain in step (1) is: 800,000 to 900,000 U of papain is added per kilogram of organic soybean meal raw material.

[0017] Further preferably, in the industrial production method of organic DHA oil as described above, the formula of the seed culture medium in step (2) is: 85-95 g / L organic glucose, 3.5-4.5 g / L soybean meal hydrolyzate (dry weight of amino nitrogen), 9-12 g / L sodium sulfate, 0.9-1.1 g / L potassium chloride, 2.8-3.2 g / L magnesium sulfate, pH = 4.0-6.0.

[0018] Further preferably, in the industrial production method of organic DHA oil as described above, the formula of the fermentation medium in step (2) is: 85-95 g / L of organic glucose, 3.5-4.5 g / L of soybean meal hydrolyzate (dry weight of amino nitrogen), 9-12 g / L of sodium sulfate, 0.9-1.1 g / L of potassium chloride, 2.8-3.2 g / L of magnesium sulfate, pH = 6.0-7.5.

[0019] Further preferably, in the industrial production method of organic DHA oil as described above, in step (3) and step (4), sugar supplementation is performed when the glucose concentration in the fermentation broth is 2-3 g / L, and the glucose concentration in the fermentation broth after each sugar supplementation is between 6-7 g / L, and sugar supplementation is no longer required after the fermentation reaches 100 hours.

[0020] Compared with the prior art, the organic DHA oil production method provided by the present invention has the following advantages and significant improvements:

[0021] (1) The raw materials used in the present invention are all organic raw materials, or non-organic raw materials permitted by organic production and processing regulations, so that the DHA product meets the organic certification standards, filling the gap in domestic organic DHA oil products.

[0022] (2) The present invention replaces the expensive organic nitrogen source with the organic soybean meal hydrolysate, while also avoiding the bottleneck problem of not being able to obtain the organic nitrogen source, thereby realizing the fermentation process of organic DHA oil; in addition, the soybean meal is pretreated by adding citric acid before hydrolysis, which not only makes the hydrolysis more complete, but also shortens the hydrolysis time by at least 12 hours, and the energy consumption of industrial production is lower, which greatly reduces the production cost.

[0023] (3) The process of the present invention is simple and suitable for industrial-scale production. At the same time, the prepared DHA oil meets the production and processing requirements of organic products in Europe, the United States, Japan, etc., so that the DHA oil can be used to prepare organic infant formula milk powder and other organic foods that comply with relevant laws and regulations. DETAILED DESCRIPTION

[0024] The present invention is further described in detail below through specific embodiments. If no specific technical operation steps or conditions are specified in the examples, they are all carried out according to the techniques or conditions described in the literature in the art or according to the product instructions. If no manufacturer is specified for the reagents or instruments used, they are all conventional products that can be obtained commercially.

[0025] Example 1: Preparation of nitrogen source

[0026] 1 kg of organic soybean meal was crushed to ensure that 100% of the organic soybean meal passed through a 20-mesh sieve; water was added to the organic soybean meal powder in a mass ratio of 1:5 to prepare an organic soybean meal powder dispersion, and then the pH of the dispersion was adjusted to 3.0 with a 10% citric acid solution, the temperature was raised to 80°C for 1 hour in a water bath, and then the temperature was lowered to 55°C; the pH was adjusted to 7.5 with a sodium hydroxide solution, and then 2 g of papain (enzyme activity of 400,000 U / g, purchased from Nanning Pangbo Bioengineering Co., Ltd.) was added, the material temperature was controlled at 55°C, enzymatic hydrolysis was performed for 12 hours, and the supernatant was taken for use by centrifugation (centrifugal speed 4000 r / min), and the hydrolysis condition was tested.

[0027] Example 2: Preparation of nitrogen source

[0028] 5 kg of organic soybean meal was crushed to ensure that 100% of the organic soybean meal passed through a 20-mesh sieve; water was added to the organic soybean meal powder in a mass ratio of 1:10 to prepare an organic soybean meal powder dispersion, and then the pH of the dispersion was adjusted to 3.0 with a 10% citric acid solution, the temperature was raised to 80° C. in a water bath for 1 hour, and then the temperature was lowered to 55° C.; the pH was adjusted to 7.5 with a NaOH solution, and then 10 g of papain (enzyme activity of 400,000 U / g, purchased from Nanning Pangbo Bioengineering Co., Ltd.) was added, the material temperature was controlled at 55° C., enzymolysis was performed for 12 hours, and the supernatant was taken for use by centrifugation (centrifugal speed 4000 r / min), and the hydrolysis condition was tested.

[0029] Example 3: Preparation of nitrogen source

[0030] 20 kg of organic soybean meal was crushed to ensure that 100% of the organic soybean meal passed through a 20-mesh sieve; water was added to the organic soybean meal powder in a mass ratio of 1:5 to prepare an organic soybean meal powder dispersion, and then the pH of the dispersion was adjusted to 3.0 with a 10% citric acid solution, the temperature was raised to 85° C. in a water bath for 1 hour, and then the temperature was lowered to 55° C.; the pH was adjusted to 7.5 with a NaOH solution, and then 40 g of papain (enzyme activity of 400,000 U / g, purchased from Nanning Pangbo Bioengineering Co., Ltd.) was added, the material temperature was controlled at 55° C., enzymolysis was performed for 12 hours, and the supernatant was taken for use by centrifugation (centrifugal speed 4000 r / min), and the hydrolysis condition was tested.

[0031] Comparative Example 1: Preparation of nitrogen source (the acid used for pretreatment is phosphoric acid, and the rest is the same as in Example 1)

[0032] 1 kg of organic soybean meal was crushed to ensure that 100% of the organic soybean meal passed through a 20-mesh sieve; water was added to the organic soybean meal powder in a mass ratio of 1:5 to prepare an organic soybean meal powder dispersion, and then the pH of the dispersion was adjusted to 3.0 with a 10% phosphoric acid solution, the temperature was raised to 80°C for 1 hour in a water bath, and then the temperature was lowered to 55°C; the pH was adjusted to 7.5 with a NaOH solution, and then 2 g of papain (enzyme activity of 400,000 U / g, purchased from Nanning Pangbo Bioengineering Co., Ltd.) was added, the material temperature was controlled at 55°C, enzymatic hydrolysis was performed for 12 hours, and the supernatant was taken for use by centrifugation (centrifugal speed 4000 r / min), and the degree of hydrolysis was detected.

[0033] Comparative Example 2: Preparation of nitrogen source (the acid used for pretreatment is phosphoric acid, the enzyme used for enzymolysis is alkaline protease, and the rest is the same as in Example 1)

[0034] 1 kg of organic soybean meal was crushed to ensure that 100% of the 20-mesh sieve passed; water was added to the organic soybean meal powder in a mass ratio of 1:5 to prepare an organic soybean meal powder dispersion, and the pH of the dispersion was adjusted to 3.0 by adding 10% phosphoric acid solution, and the temperature was raised to 85°C in a water bath for 1 hour; then the temperature was lowered to 55°C; the pH of the phosphoric acid pretreatment liquid was adjusted to 8.0 with NaOH solution, and then 2 g of alkaline protease (enzyme activity of 400,000 U / g, purchased from Novozymes Co., Ltd.) was added, the material temperature was controlled at 55°C, enzymatic hydrolysis was carried out for 12 hours, centrifuged (centrifugal speed 4000 r / min), the supernatant was taken for use, and the hydrolysis condition was tested.

[0035] Comparative Example 3: Preparation of nitrogen source (the acid used for pretreatment is hydrochloric acid, and the rest is the same as in Example 1)

[0036] 1 kg of organic soybean meal was crushed to ensure that 100% of the 20-mesh sieve passed; water was added to the organic soybean meal powder in a mass ratio of 1:5 to prepare an organic soybean meal powder dispersion, and then the pH of the dispersion was adjusted to 3.0 with a 10% hydrochloric acid solution, the temperature was raised to 80°C for 1 hour in a water bath, and then the temperature was lowered to 55°C; when the temperature of the dispersion dropped to a suitable temperature, the pH was adjusted to 7.5, and then 2 g of papain (enzyme activity of 400,000 U / g, purchased from Nanning Pangbo Bioengineering Co., Ltd.) was added, the material temperature was controlled at 55°C, enzymatic hydrolysis was carried out for 12 hours, centrifuged (centrifugal speed 4000 r / min), the supernatant was taken for use, and the hydrolysis condition was tested.

[0037] Determination method of amino nitrogen:

[0038] Pipette 5.0ml of the sample into a 100ml volumetric flask, add water to the mark, mix well and pipette 20.0ml, record as V 0 , put it in a 200ml beaker, add 60ml water, turn on the magnetic stirrer, and titrate with 0.05mol / L sodium hydroxide standard solution until the pH meter indicates PH = 8.2, record the volume of sodium hydroxide standard solution consumed, and calculate the total acid content. Add 10.0ml formaldehyde solution and mix well. Continue to titrate with sodium hydroxide standard solution until PH = 9.2, and record the volume of sodium hydroxide standard solution consumed V 1 ; At the same time, absorb 80ml of water, first adjust the pH to 8.2 with sodium hydroxide standard solution, then add 10.0ml of formaldehyde solution, titrate with sodium hydroxide standard solution to pH = 9.2, and record the volume of sodium hydroxide standard solution consumed, recorded as V 2 , as a blank test.

[0039] The content of amino nitrogen in the sample is calculated as follows:

[0040]

[0041] The conversion rate is calculated as follows:

[0042]

[0043] Table 1: Comparison of amino nitrogen content and conversion rate of soybean meal hydrolysate prepared by different methods

[0044]

[0045] It can be seen from the data in Table 1 that the hydrolysis degree of Example 1 is the best, the amino nitrogen content in the hydrolyzate is 17.78%, and the conversion rate is as high as 95.51%, which can provide a good nitrogen source for the fermentation process and ensure the nitrogen source required for the normal growth of microorganisms.

[0046] Example 4: Preparation of organic DHA oil

[0047] The formula ratio of organic DHA oil fermentation medium is: organic glucose 90g / L, organic nitrogen source content 3g / L (prepared according to the method of implementation 1), sodium sulfate 10g / L, potassium chloride 1g / L, magnesium sulfate 3g / L; the actual addition amount is converted into the feed amount according to the actual amount required for production.

[0048] The seed solution of the shake flask was transferred to the seed tank through the sterile inoculation port at a 10% (V / V) inoculation rate for cultivation. The pH of the fermentation medium was controlled at 5.5, the stirring speed was controlled at 120 rpm, and the ventilation volume was controlled at 0.4 m 3 / h, and the culture temperature was controlled at 28°C for 5 days; then the inoculation was transferred to the expansion tank according to the inoculum amount of 10% (V / V), the pH of the fermentation medium was controlled at 7.0, the stirring speed was controlled at 300rpm, and the ventilation volume was controlled at 1.0m 3 / h, and the culture temperature was controlled at 28°C for 6 days. The biomass, total oil, and DHA content of the fermentation broth were tested by sampling.

[0049] Example 5: Preparation of organic DHA oil

[0050] The formula ratio of organic DHA oil fermentation medium is: organic glucose 90g / L, organic nitrogen source content 3g / L (prepared according to the method of Implementation 2), sodium sulfate 10g / L, potassium chloride 1g / L, magnesium sulfate 3g / L; the actual addition amount is converted into the feed amount according to the actual amount required for production.

[0051] The seed solution of the shake flask was transferred to the seed tank through the sterile inoculation port at a 10% (V / V) inoculation rate for cultivation. The pH of the fermentation medium was controlled at 5.5, the stirring speed was controlled at 120 rpm, and the ventilation volume was controlled at 0.4 m 3 / h, and the culture temperature was controlled at 28°C for 5 days; then the inoculation was transferred to the expansion tank according to the inoculum amount of 10% (V / V), the pH of the fermentation medium was controlled at 7.0, the stirring speed was controlled at 300rpm, and the ventilation volume was controlled at 1.0m 3 / h, and the culture temperature was controlled at 28°C for 6 days. The biomass, total oil, and DHA content of the fermentation broth were tested by sampling.

[0052] Example 6: Preparation of organic DHA oil

[0053] The formula ratio of organic DHA oil fermentation medium is: organic glucose 90g / L, organic nitrogen source content 3g / L (prepared according to the method of Implementation 3), sodium sulfate 10g / L, potassium chloride 1g / L, magnesium sulfate 3g / L; the actual addition amount is converted into the feed amount according to the actual amount required for production.

[0054] The seed solution of the shake flask was transferred to the seed tank through the sterile inoculation port at a 10% (V / V) inoculation rate for cultivation. The pH of the fermentation medium was controlled at 5.5, the stirring speed was controlled at 120 rpm, and the ventilation volume was controlled at 0.4 m 3 / h, and the culture temperature was controlled at 28°C for 5 days; then the inoculation was transferred to the expansion tank according to the inoculum amount of 10% (V / V), the pH of the fermentation medium was controlled at 7.0, the stirring speed was controlled at 300rpm, and the ventilation volume was controlled at 1.0m 3 / h, and the culture temperature was controlled at 28°C for 6 days. The biomass, total oil, and DHA content of the fermentation broth were tested by sampling.

[0055] 1. Biomass determination method

[0056] Measure 100 ml of fermentation liquid, centrifuge to remove the supernatant, transfer the lower layer of bacteria to a dry plate, place it in a 105°C oven to dry to constant weight, take it out, cool it, weigh it, and then divide it by the unit volume to get the biomass per unit volume in the fermentation liquid.

[0057] 2. Determination method of total oil

[0058] 1) Take 100mL of fermentation liquid and centrifuge at 4000r / min for 5min, remove the supernatant, transfer the lower layer residue into a 500mL conical flask with 100mL of pure water, add 2g of alkaline protease, and place in a 60℃ water bath for 50-60min, maintaining stirring at an appropriate rate during the period. Observe the cell wall breaking under a microscope every 30min, and take out if the cell wall is completely broken. (Note: After adding 2g of alkaline protease, the pH can be adjusted to 8.0-8.5 with NaOH solution if necessary).

[0059] 2) Add 100mL of anhydrous ethanol, then add an appropriate amount (generally 100-200mL) of n-hexane, heat and stir on a magnetic stirrer until slightly boiling, remove, and let stand for stratification. If the emulsification is severe and it is difficult to stratify, add saturated salt water or NaCl to stratify. If the effect is not ideal, continue to add an appropriate amount of anhydrous ethanol, shake well, and let stand for stratification. Transfer the organic layer to a 500mL flask with constant weight, and remove the solvent in the flask by rotary evaporation. Second extraction: Add an appropriate amount (generally 100-200mL) of n-hexane, and operate as before. If necessary, continue to add an appropriate amount of anhydrous ethanol. Third extraction: Repeat the previous step to extract. Until the oil is extracted cleanly, remove the solvent in the flask by rotary evaporation, dry at 60℃ and vacuum for 2-4h, weigh, and calculate the weight of oil per unit volume by the mass difference.

[0060] 3. DHA content determination method

[0061] Take 50mg of DHA oil in a 10ml centrifuge tube, add 2ml of n-hexane (HPLC) to dissolve the oil, add 4mL of potassium hydroxide-methanol solution (0.4mol / L), place in a 35℃ water bath for 30min, shake on a vortex shaker for more than 10s every 5min, then add 2ml of saturated salt water and shake well. Centrifuge at 8000r / min for 5min, take the supernatant (filter with a needle filter membrane if necessary) and use GC for component analysis, and calculate the DHA content by the peak area ratio of DHA to the peak area ratio of all fatty acids.

[0062] The test results are shown in Table 2 below:

[0063] Table 2: Biomass, total oil and DHA content in fermentation broth

[0064] Biomass, g / 100ml Total oil, g / 100ml DHA content, g / 100g Example 4 9.3 5.8 50.9 Example 5 8.0 4.5 45.6 Example 6 7.7 3.8 43.6

[0065] It can be seen from the experimental results in Table 2 that the biomass, total oil, and DHA content of the fermentation broth of each embodiment of the present invention are maintained at a relatively high level. The main reason is that during the hydrolysis of soybean meal, the present invention uses citric acid for pretreatment, thereby protecting the protein from being destroyed during the hydrolysis process, so that the amino nitrogen content in the enzymatic hydrolyzate is relatively high, which better provides a nitrogen source for the production of DHA strains, and is utilized by microorganisms to obtain a higher yield of DHA oil and pure DHA. The hydrolyzate of soybean meal contains a small amount of residue, and the residue contains trace elements, which are conducive to the growth of microorganisms.

[0066] The above is only a preferred specific implementation method of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent substitutions or changes within the technical scope disclosed by the present invention according to the technical scheme and inventive concept of the invention, which should be covered by the protection scope of the present invention.

Claims

1. An industrial production method of organic DHA oil, characterized in that: The method comprises the following steps: (1) Preparation of nitrogen source: grind the organic soybean meal raw material and add water to make a dispersion, adjust the pH to 2.9-3.1 with citric acid solution, raise the temperature to 80-85°C, keep the temperature in a water bath for 40-60 min, then cool to 50-55°C, adjust the pH to 7-8, add papain, and hydrolyze at 50-55°C for 10-12 h to obtain soybean meal hydrolyzate for later use; (2) preparing a culture medium: preparing a seed culture medium and a fermentation culture medium for Schizochytrium, wherein the nitrogen source in the seed culture medium and the fermentation culture medium is the soybean meal hydrolyzate prepared in step (1); (3) Seed culture: The seed solution of Schizochytrium schizochytrium was transferred to a seed tank containing seed culture medium through a sterile inoculation port at a volume ratio of 1-10% and cultured for 3-5 days. During the seed culture, the pH of the culture medium was controlled at 4.0-6.0, the stirring speed was 100-120 rpm, and the ventilation volume was 0.3-0.5 m 3 / h, the culture temperature is 26~28℃; (4) Fermentation culture: The inoculation volume is 10-15% and the inoculation volume is transferred to a fermentation tank containing fermentation medium through a sterile inoculation port for 4-6 days. During the fermentation process, the pH of the medium is controlled at 6.0-7.5, the stirring speed is 200-300 rpm, and the ventilation volume is 0.5-1.0 m 3 / h, the culture temperature is 26~28℃; The dispersion in step (1) is prepared by mixing the organic soybean meal raw material and water in a mass ratio of 1:(4-6); The mass fraction of the citric acid solution in step (1) is 5-15%; The dosage of papain in step (1) is: adding 800,000 U to 900,000 U of papain per kilogram of organic soybean meal raw material; The formula of the seed culture medium in step (2) is: 85-95 g / L organic glucose, 3.5-4.5 g / L soybean meal enzymatic hydrolysate, 9-12 g / L sodium sulfate, 0.9-1.1 g / L potassium chloride, 2.8-3.2 g / L magnesium sulfate, pH=4.0-6.0, wherein the soybean meal enzymatic hydrolysate is calculated based on the dry amount of amino nitrogen; The formula of the fermentation medium in step (2) is: 85-95 g / L organic glucose, 3.5-4.5 g / L soybean meal hydrolysate, 9-12 g / L sodium sulfate, 0.9-1.1 g / L potassium chloride, 2.8-3.2 g / L magnesium sulfate, pH=6.0-7.5, wherein the soybean meal hydrolysate is calculated based on the dry amount of amino nitrogen.

2. The industrial production method of organic DHA oil according to claim 1, characterized in that: The particle size of the organic soybean meal raw material after crushing in step (1) is less than 20 mesh.

3. The industrial production method of organic DHA oil according to claim 1, characterized in that: In step (3) and step (4), the glucose supplementation operation is performed when the glucose concentration in the fermentation broth is 2-3 g / L, and the glucose concentration in the fermentation broth is between 6-7 g / L after each glucose supplementation.

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