Novel Preparation Process Of Conjugated Linoleic Acids

Conjugated linoleic acids(CLAs) have various bioactivities such as anticarcinogenic activity, body fat reduction, lowering atherosclerosis, which have been widely applied in food, pharmaceutical, health care and cosmetic fields. However, amounts of natural CLAs are too little to satisfy the demands of people. Therefore, preparation of CLAs with high purity using safflower oil with high content of linoleic acid(LA) as starting material has been investigated. Namely, safflower oil was firstly saponified and isomerized into mixed fatty acids including CLAs, oleic acid, stearic acid and palmitic acid, and subsequently CLAs were purified by liquid-liquid extraction.Firstly, we studied the synthesis of CLAs using low boiling point alcohols as solvents and inorganic alkali as catalyst. The results showed that sodium hydroxide, potassium hydroxide and sodium methoxide had good catalytic activity and high conversion and yield were obtained when using methanol, ethanol, n-propanol, and i-propanol as solvents, which the separation of products has been greatly simplified. Methanol and sodium hydroxide were selected as reaction solvent and catalyst , respectively, considering the low price and high efficiency. The optimum reaction conditions obtained from the results of single factor experiment and Uniform Design were reaction temperature 177℃, reaction time 1 h, the NaOH concentration 5.6% and the safflower oil concentration 5.0%. Under above conditions, the reaction conversion and the yield of total CLAs reached 98.2% and 88.9%, respectively.Subsequently, liquid-liquid extraction was employed to separate CLAs from mixed fatty acids obtained by alkaline isomerization for the first time, which has advantages of high throughput, high yield and simple operation compared to conventional separation methods such as urea complexation and adsorption chromatography. Firstly, based on the structural characteristics of separation objects, a series of biphasic systems were established. Comprehensively considering many factors such as separation selectivity coefficient, distribution coefficient and emulsification , furfural was selected as extractant ultimately. Then , a series of liquid-liquid equilibrium data were determined. Through calculation and design, fractional extraction was employed for a multistage countercurrent extraction process. The experimental results showed that the purity and recovery of CLAs were 97.2% and 62.5% when extraction section and washing section were with a number of theoretical stages of two and four, respectively, which were in accordance with the results of theoretical calculation. Furfural was recycled by vacuum distillation and the product was washed by water. Finally, bright yellow CLAs product with the purity of 97.4% was obtained.