Study On The Preparation Of Emulsions With Medium- And Long-chain Triacylglycerols And Its Anti-obesity Efficiency

In this study,the medium and long chain triglycerides(MLCT)were prepared from Camellia oil(CO)and camphor tree seed oil(CCSO).It was expected to provide scientific data for the synthesis and application of functional structural lipids.The main results of the present study were as follows:1.The medium and long chain triglycerides(MLCT)were synthesized by CO and CCSO using immobilized lipase as a catalyst.The purity of interesterified product was conducted by molecular distillation.Results showed that 95.57% of purified MLCT was obtained under the optimal conditions as follows: feed rate 1mL/min,scraper speed 250r/min,heating temperature of 170℃.Fatty acid profiles and physiochemical characteristics of the interesterified product were investigated.Results showed that the MCFA(from CCSO)were higher at Sn-2 position of TAG,reaching 43.13%(total 35.66%).Meanwhile,LCFA(from CO)were also higher at Sn-2 positions,reaching 10.33%(6.35%).Namely,SFA were mainly distributed at the Sn-2 position,reaching 53.96%(total 42.46%),while the content of oleic acid was 41.49%(total 52.10%).LCFA distributed at Sn-2 positions can be quickly digested and absorbed,which could be beneficial for the use of fat in human body.2.Ultrasonic emulsification technology was used to prepare the medium-and long-chain triacylglycerol nanoemulsions and the changes of different nanoemulsion and structural fat in digestion process were discussed.The parameters in the ultrasonic emulsification process were optimized.The results showed that the optimal parameters of the preparation of medium and long-chain triacylglycerol nanoemulsions were: ultrasound power 400 W,ultrasound time 15 min,emulsifier 3 %,and medium-and long-chain structure ester 6 %.The average particle size of the nanoemulsions was 85 ± 1.43 nm,and the nanoemulsions were stable during the one month storage experiment.The medium and long-chain triacylglycerol nanoemulsions also had good pH stability.Different emulsifiers have a great influence on the particle size and digestion properties of the prepared nanoemulsions.The particle size of nanoemulsion preparated by sucrose ester was the smallest,while span 80 was largest.However,the sucrose ester stabilized nanoemulsion was unstable to flocculate in the stomach stage,following a decrease in particle after in intestine.Conversely,the nanoemulsions with Tween 80 and Span 80 behaved fairly similar trend at simulated digestion model: the gatric fluid had no remarkable effect on the diameter and charge of emulsions.There was an appreciable increase in average size and negative charge of droplets after intestine incubation.The initial sizes of nonoemulsions were 3651,244.20,125.70 nm.The rate and extent of structured lipid digestion strongly depend on the initial droplet size,increasing with decreasing particle diameter.After intestinal digestion,the release of fatty acids was 34.13%,70.58% and 79.33%,respectively.3.The effects of tea oil,camphor seed oil and medium and long chain ester ester on digestion and absorption were compared by acute animal experiment.Fatty acids in the blood and liver were determinated.SD male rats were randomly divided into 4 groups(K,CO,CCSO,MLCT)according to the fasting weight,and were orally administered distilled water,CO,CCSO and MLCT.After 1 hour,3 hours,5 hours,respectively,rats of each group were sacrificed,then,blood dsampling were taken from the abdominal aortic ateroia and serum TG,TC and fatty acid composition were measured.Slice of liver tissue was made into homogenates,and fatty acid composition was determined.The results of acute gavage experiment showed that rats fed MLCT or CCSO after one hour,the concentration of serum TG reached a peak,and then began to decline.Finally,it maintained in a relatively stable state which indicated that the synthesis of MLCT and MCT digestion as fast.But serum TG in tea oil group reached a peak at 3 h and maintained a high state.MLCT and MCT had little effect on serum cholesterol,but tea oil increased TC at 3 h.It was interesting to note that the medium-chain fatty acids in the liver phospholipids of the MLCT group and the CCSO group were significantly increased,while the oleic acid in the tea oil group was significantly increased,indicating that MLCT and MCT mainly affected the phospholipid fatty acid composition in the liver,whie LCFA mainly affected the fatty acid composition of triglycerides in the liver.These differences may reflect the difference between the absorption mechanism of MCT and LCT and its functional role in vivo.4.The effects of camphor seed oil and medium-and long-chain ester on lipid metabolism were studied by long-term animal experiment.50 C57BL/6J mice were randomly divided into five groups(control group,cholesterol group,Lard group,CCSO group and MLCT group)(n=10)according to the fasting weight,and were given corresponding feed.After 6 weeks,body weight,liver,epididymal pads,perirenal fat pads were weighed,and the body length,hepatic and fecal lipids,enzymes related to lipid metabolism in adipose tissue were measured.Serum TG,TC and HDL-C and LDL-C,HDL-C/LDL-C ratio were measured and calculate,Another slice of liver tissue was made into homogenates,and concentration of protein,TG,TC,ApoA1 and ApoB were determined and ApoA1/ApoB ratio was calculated.At the same time,the epididymal adipose tissue was kept for HE staining.Results showed that a dietary intake of MLCT and CCSO were found to have beneficial effects on helping prevent obesity,reducing body fat,and decreasing blood triglyceride,cholesterol and LDL-C levels in C57BL/6J mice.MLCT and CCSO could also reduce the concentrations of TC,ApoA1,ApoB of liver homogenates.MLCT and CCSO decreased the deposition of lipid in the liver by reducing the levels of C16: 0,C18: 0 and LA in TG and phospholipids.The mechanism appears to be explained by that MLCT might be useful for controlling lipid metabolism in hepatic and fat absorption in the intestine.Another potential mechanim was that MLCT increased steatolysis by improving the level of enzyme related to adipose lipid mobilization in adipose tissue.