Study On Enzymatic Synthesis Technology Of Medium/Long Chain Fatty Acids Triglycides

Oils and fats can provide heat energy and essential fatty acids for human.It can effectively promote the absorption of fat-solibe vitamins.But with the improvement of the living standard,the intake of edible fat(high fat foods,animal food)is increasing in people's diet.Cooking oil causes a series of related disease such as hypertension,obesity,and arteriosclerosis is higher and higher.Develop low-calorie oils becomes one of the hot topics in oil research area.Medium and long chain fatty acid triglyceride(MLCT)is a low-calorie structural lipid formed by combining with specific medium chain fatty acids based on the original long chain fatty acids of edible oils.It has natural oils characteristics and physiological function,such as rapid energy supply,lowering serum cholesterol content,prevention and relief of obesity.Through single factor and orthogonal experiments,the synthes is process of medium and long-chain structured lipids was studied by high oleic peanut oil and caprylic acid in the present of immobilized lipases.The urea fatty acid was used to remove the free fatty acids in the product,and the purity of the product was improved.The main findings are as follows:(1)High oleic peanut oil was main composed of long chain unsaturated fatty acids such as oleic acid and linoleic acid,while oleic acid,linoleic acid and arachidonic acid content was respectively 64.33%,20.14% and 2.09%,saturated fatty acids account for only 12.81%.The Sn-2 fatty acid of high oleic peanut oil was detected by GC-TCL.It was found that the highest content of oleic acid was 61.63%,followed by linoleic acid 27.32%,palmitic acid 4.47%,stearic acid 2.02% and linolenic acid 1.17%.Oleic acid has physiological functions such as lowering blood lipids.Therefore,high oleic acid peanut oil is an ideal raw material for MLCT synthesis.(2)Medium and long chain fatty acid triglycerides were synthesized by enzymatic interesterification of two different lipases as catalyst in solvent-free system.The results showed that the immobilized lipase Lipozyme RM IM was the best catayst.Therefore,Lipozyme RM IM lipase was selected for subsequent experimental research.Single factor experiment and reponse surface methodology were used to study reaction time,substrate molar ratio,add water,reaction temperature and enzyme load on transesterification.It was found that the degree of influence of each factor on the caprylic acid insertion rate in descending order: substrate molar ratio > enzyme amount added > reaction temperature >water addition amount.The optimized conditions for lipase-catalyzed acidolysis of acidolysis of high oleic peanut oil with caprylic acid were molar ratio of high oleic peanut oil to caprylic acid 1:3.41,11.85% of the total weight of immobilized lipase,11.97% of the total weight of substrates for immobilized lipase,reaction 20 h at 45.8?,the caprylic acid incorporation reached 41.19%,which was close to the the model prediction 43.14%.(3)Urea adduction fractionation was used to refine the SLs.The product acid value reached a minimum of 2.37 when the weight ratio of oil to urea was 1:2.Under this condition,the TAG content of SLs was 68.36%.The obtained structural fat product is a light yellow liquid,transparent,and the product has good purity.In addition,the yield of the purified product was researched and found that the yield of the urea inclusion compound was 75.47%,and the structural lipid was less lost during the urea inclusion purification process.(4)The fatty acid composition of the raw oil and purified product was analyzed,and the results showed that the position of the triglyceride fatty acid of the product was significantly changed.At the Sn-1,3 position of the structural lipid triglyceride molecular skeleton,the original long-chain fatty acid of the raw oil was replaced by caprylic acid.The oleic acid was the main fatty acid at the Sn-2 position,which indicated that the synthesized structural lipid was MLCT.The physicochemical properties of the purified product included: acid value 2.37 mg KOH/g,iodine value 95.76g/100 g,saponification value is 220.54 mg KOH/g,and the peroxide value was 2.19mmol/Kg,which all met the national hygienic standard for edible vegetable oil GB2716-2018.