Research On Synthesis Of Diacylglycerol By Lipase

Diacylglycerol is a kind of structured lipid which some fatty acid of triglyceride is replaced by hydroxy, it is also called diglyceride. Diacylglycerol is the natural component of fats, but the content is usually less than 5%. In recent years, many researches have shown that diacylglycerol can suppress the increase of weight, and can prevent and treat hyperlipidemia and cardiovascular disease and other diseases about cerebrovascular. Using lipase as catalyst, the paper studied the process of synthesis of diacylglycerol by partial hydrolysis, and optimized the process of synthesis of diacylglycerol. Meanwhile, the paper also had a preliminary study about removing free fatty acids by molecular distillation, and analysis and identification of diacylglycerol.Firstly, using peanut oil as raw material, the study discussed the process of synthesis of diacylglycerol by partial hydrolysis, catalyzed by lipase. The content of diacylglycerol was confirmed by high performance liquid chromatography. The influence of factors on reaction, such as enzyme dosage, water content, reaction time, and reaction temperature were investigated. The orthogonal experiment was adopted to optimize the parameters of synthesis of diacylglycerol. The results showed that lipase had the best catalysis under reaction temperature 40-60 ℃. The orthogonal experimental results indicated the best technology of synthesis of diacylglycerol by partial hydrolysis as follows:enzyme dosage 20 U/g (base on oil), reaction time 2.5 h, water content 15%(base on oil), reaction temperature 40 ℃. In this condition, peanut oil diacylglycerol content was 36.58%. Compared with diacylglycerol content in peanut oil, it was increased by nearly twelve times.Secondly, free fatty acids produced in the enzymatic reaction, were removed by molecular distillation. A series of influence factors on reaction were investigated, such as distillation temperature, casting speed and the condensate water temperature. By the single-factor experiments, the best technology of removing free fatty acids have been identified as follows:distillation temperature 140 ℃, casting speed 200 r/min, the condensate water temperature 35℃.Under this condition, peanut oil enzymatic hydrolysate of acid value was from 68.8 mg/g to 2.14 mg/g. From the results, we saw that molecular distiaiiation could effectively remove the free fatty acids.Finally, using peanut oil and chick fat as raw materials, the study discussed crude oil, enzymatic hydrolysate and purified enzymatic hydrolyzate by thin-layer chromatography, high performance liquid chromatography and gas chromatography. From the TLC and HPLC experiments, molecular distillation indeed removed free fatty acids. Monoglycerides were also partially removed during the purification process. At the same time, it had diacylglycerol in the purified enzymatic hydrolysate of peanut oil and chicken fat, and the content of diacylglycerol was respectively 43.07% and 41.99%. From the GC experiments, the content of unsaturated fatty acids of purified enzymatic hydrolyzate of peanut oil was higher than chicken fat. Compared with the crude oil, in the purified enzymatic hydrolyzate of peanut oil and chicken fat, the content of unsaturated fatty acids (such as oleic acid and linoleic acid) were increased, the content of saturated fatty acids were decreased. The study also revealed that it had saturated fatty acids and unsaturated fatty acids in the enzymatic hydrolyzate. And the content of unsaturated fatty acids was larger than saturated fatty acids. In the enzymatic hydrolyzate, it had 1,2-diacylglycerol and 1,3-diacylglycerol. The content of 1,3-diacylglycerol was higher than 1,2-diacylglycerol.