Dehydroacetic Acid CAS 520-45-6

Preparation of crude fish oil Take the fresh fish liver that has removed the gallbladder, washed and chopped, put it in a pot, add water, pass steam to 80 ° C, flow out the oil, filter, cool the filtrate to 0 ° C, precipitate solid fat, and filter under pressure , the filtrate is crude fish oil. Fish oil[water]→[80℃]oil quality[filtration]→crude fish oil or minced fish as raw material, minced and mixed with starch at 7-10℃, extracted with hexane for 15min, filtered to obtain filtrate. The filtrate was washed with sodium chloride solution, dehydrated by adding anhydrous sodium sulfate, and hexane was recovered to obtain crude fish oil. Minced fish [starch, hexane]→[7-10℃, 15min] filtrate [NaCl]→[anhydrous sodium sulfate] crude fish oil Preparation of refined fish oil Take crude fish oil, add sodium hydroxide ethanol solution to saponify, filter, The filtrate was acidified with acid, extracted with an organic solvent insoluble in water, the extract was washed with water, and the organic layer was removed. The aqueous layer was a light red or reddish-brown clear liquid, which was placed at 10°C for 30 minutes without solid precipitation to obtain refined fish oil. Crude fish oil [alkaline ethanol solution] → filtrate [organic solvent] → [HCl] extract [water washing] → refined fish oil pre-concentration, alcoholysis and ethyl esterification of refined fish oil, and urea inclusion crystallization method to saturate the fish oil The fatty acid with less degree is removed to obtain fish oil fatty acid ethyl ester. Refined fish oil [ethanol, urea inclusion crystal] → preparation of fish oil fatty acid ethyl ester DHA Put the fish oil fatty acid ethyl ester into the extraction tank, open the steel cylinder, after the CO2 is condensed, pressurize it to the set pressure by the high-pressure metering pump, and then preheat it. After heating to the working temperature, enter the extraction tank. SC-CO2 carries fish oil fatty acid ethyl ester into the rectification column, the components come out from the top of the column according to the solubility, and enter the separator to receive after decompression. Experimental conditions: the extraction pressure is 11-15MPa, and the extraction temperature is 35°C; the rectification pressure is 11-15MPa, and the rectification temperature is 40-85°C. Collect the EPA-rich fraction of 12-13.5MPa and the DHA-rich fraction of 14-15MPa, and measure by gas chromatography, EPA+DHA is purified to 90%. The EPA-rich fraction and the DHA-rich fraction are subjected to secondary extraction at 11.5-13MPa and 13.5-15MPa respectively, EPA is purified to 67%, and DHA is purified to more than 90%. Fish oil fatty acid ethyl ester [supercritical CO2 extraction] → [separation] DHA

Extraction of fish oil Mince herring leftovers, add half the amount of water, adjust pH to 8.5-9.0, keep warm for 45 minutes, add 5% salt, stir to dissolve, continue to keep warm for 15 minutes, filter, press filter residue, combine filtrate and pressing liquid , Centrifuge while hot to obtain herring oil. The total content of EPA and DHA in herring oil was 8.9%. Herring scraps [H2O, 5%NaCl] → [pH8.5-9] [filtration, centrifugation] → preparation of herring oil polyunsaturated fatty acid (PUFA) Herring oil was added with sodium hydroxide ethanol (95%) solution, Nitrogen-filled reflux saponification, the saponification liquid is cooled to 15-20 ° C, a large amount of fatty acid sodium salts are precipitated, squeezed and filtered, the filtrate is cooled to -20 ° C, and then pressure filtered. Add an equal volume of water to the filtrate, adjust pH to 3-4, and centrifuge for 10 min to obtain PUFA-I. Dissolve PUFA-I in ethanolic sodium hydroxide solution, cool at -20°C, filter under pressure, add a small amount of water to the filtrate, cool at -10°C, and filter Chemicalbook to remove cholesterol crystals. A small amount of water was added to the filtrate, cooled at -20°C, centrifuged for 5 minutes, the upper layer was poured out, and the lower layer of gelatin (PUFA sodium salt) was acidified and centrifuged for 10 minutes to obtain PUFA-II. The total content of EPA and DHA in PUFA-II was 64.8%. Herring oil [NaOH ethanol] → [nitrogen] saponification solution [cooling] filtrate [pH3-4] → [centrifugation] PUFA-I [NaOH ethanol] → PUFA-II

Using arachidonic acid as raw material, after desaturation, EPA is obtained. EPA is extended by C2 chain to obtain docosapentaenoic acid. Docosapentaenoic acid is desaturated to give DHA. Arachidonic acid [desaturation]→EPAEPA[C2 chain extension]→docosapentaenoic acid [desaturation]→DHA

At present, the high-vacuum distillation method, molecular distillation method, silver nitrate complex method, simple supercritical CO2 extraction and industrial chromatographic preparation process commonly used at home and abroad all have many drawbacks and deficiencies, and are not suitable for high-purity EPA and DHA. Industrial development. The supercritical multi-fluid precision rectification technology is used to directly separate high-purity EPA and DHA. It is operated under normal temperature conditions. The product is not easy to be oxidized and degraded. production.

The process of extracting fish oil is to use light lye to decompose the protein tissue of fish liver and destroy the binding relationship between protein and liver oil, so as to separate fish oil more fully. This method of liver oil is of good quality and low price, and many fish oil factories in my country use this method to produce fish oil.

The light alkali used in the traditional light alkali hydrolysis method to extract fish oil is a dilute solution of sodium hydroxide, and the salt is a sodium chloride solution, and the process is very mature. However, the waste liquid produced by the extraction process has a high content of sodium salt and cannot be further utilized, thus forming a new waste. According to the extraction principle of the light alkaline hydrolysis process, Yang Guane et al. replaced the sodium hydroxide and sodium chloride in the light alkaline hydrolysis process with potassium hydroxide and potassium nitrate, and the extraction rate and quality of fish oil remained stable; the waste residue and waste liquid after extraction of fish oil It contains a large amount of amino acids and proteins, which can be further utilized as raw materials of high-efficiency green fertilizers, and no new wastes are generated. The extraction method is as follows: after a certain amount of cod liver is homogenized in a homogenizer, add it to a three-necked flask, add half to one and a half volumes of water, stir and heat the water bath to 45-50°C, add 40% potassium hydroxide in two times Aqueous solution, adjust pH to 8-9, continue stirring to heat up to 80-90 ℃, keep warm for 30 minutes, add 4% potassium nitrate by weight of fish liver, continue stirring, salt out for 15 minutes, centrifuge while hot, and separate crude fish oil. Cod liver[water]→[45-50℃][4%KOH]→[pH8-9][80-90℃]→[30min][4%KNO3]→[15min][centrifugation]→crude fish oil

Product determination method: peroxide value-sodium thiosulfate back-dropping method; acid value-base titration method; iodine value-sodium thiosulfate titration method; saponification value-hydrochloric acid back-dropping method; DHA, EPA content determination-gas chromatography . Results (n=3): fish oil extraction rate was 24.4%; acid value was 2.58; iodine value was 309; saponification value was 178.7; peroxide value was 0.070%; DHA content was 19.60%.