1. Naturally occurring Conjugated Linoleic Acid Deutsch mainly exists in the milk fat and meat products of rumen animals, such as cattle and sheep, and each gram of milk fat contains 2-25 mg, and the content of CLA increases with the age of the cow. The formation of Conjugated Linoleic Acid Deutsch is due to the anaerobic Vibrio cellolyticum linoleic acid isomerase in the gut of ruminants that can convert linoleic acid into CLA, and mainly into biologically active cis-9, trans-11 isomer. CLA is also present in small amounts in the tissues, blood and body fluids of other animals. CLA is also found in human milk.
2. Synthesis Conjugated Linoleic Acid Deutsch can be synthesized by alkali-catalyzed isomerization with linoleic acid or vegetable oil rich in linoleic acid as substrate. The initial synthetic CLA is a mixture of various isomers, mainly containing cis-trans, trans-cis isomers and a small amount of cis-cis, trans-trans isomers. The improved synthesis process can make CLA more purified, the content of cis-9, trans-11 and trnas-10, cis-12 isomers exceeds 50%, and the non-Conjugated Linoleic Acid Deutsch composition is less than 1%. At present, there are mainly the following synthetic methods for artificial synthesis.
(1) Alkaline isomerization of linoleic acid: Using natural vegetable oil as raw material, KOH as catalyst and propylene glycol as solvent, mixing and refluxing in the presence of nitrogen protection and heating, adding aqueous solution after refluxing, and adjusting pH value with hydrochloric acid , extracted with n-hexane, the extract was washed with brine, dried with magnesium sulfate, and finally concentrated under reduced pressure to obtain a mixture of conjugated linoleic acid. This basic isomerization method has simple process, and the obtained product is non-toxic and easy to handle, so it is widely used and suitable for producing conjugated linoleic acid from vegetable oil rich in linoleic acid, such as soybean oil, red Flower oil, cottonseed oil, corn oil, etc., its products can be widely used in food processing.
(2) Dehydration of oleic acid allyl alcohol Allyl oleic acid is oleic acid allyl alcohol which is produced by oleic acid by light to generate peroxide, and is reduced to obtain 8-hydroxyl or 11-hydroxyl oleic acid allyl alcohol. Allyl oleate is a secondary product of oleic acid, which exists in natural foods and can be dehydrated and converted to conjugated linoleic acid under acid-catalyzed (BF3, HCl) conditions. The specificity of G. candidum lipase was used to methylate conjugated linoleic acid. Because of the specificity of this lipase to cis-9, trans-11-octadecadienoic acid, it could be Methyl esterification has no effect on trans-10,cis-12-octadecadienoic acid. Molecular distillation technology can be used to obtain cis-9,trans-11-octadecadienoic acid with higher purity.
(3) Esterification method Castor oil is dissolved in dichloromethane and methanol solution, and esterification occurs under the conditions of sodium and reflux to generate methyl ricinoleate. The separated and purified methyl ricinoleate can react with 12-methylsulfonyl chloride to generate methyl 12-methanesulfonyl oleate, and the toluene solution of methyl 12-methanesulfonyl oleate in DBU (1,8 -diazabicyclo[5.4.0]undecan-7-ene) under the catalysis of reflux, the obtained complete digestion product is mainly cis-9,trans-11-octadecadienoic acid methyl ester. Using urea for separation and purification can obtain a conjugated linoleic acid product with higher purity.
(4) Microbial fermentation method Microbial fermentation method uses linoleic acid isomerase in microorganisms to convert linoleic acid into conjugated linoleic acid. From the research results obtained so far, lactic acid bacteria are ideal strains, especially acidophilic lactic acid bacteria can effectively convert linoleic acid or glycerol linoleate into conjugated linoleic acid. Lactic acid bacteria contain linoleic acid isomerase, and its action site is the C12 double bond of the fatty acid instead of the C9 double bond, so that it can convert linoleic acid into cis-9, trans-11-octadecadienoic acid , instead of other isomers, the obtained Conjugated Linoleic Acid Deutsch can be directly extracted from the cell culture medium.