Study On The Method Of Detection And Enrichment Of Vaccenic Acid And Conjugated Linoleic Acids In Butter

Various researchers have highlighted the health benefits of some fatty acidsnaturally found in milk fat while searching for alternatives to add value to milk fat.Among these, conjugated linoleic acid (CLA) has been shown to have health benefits,such as reducing the risk of cancer and atherosclerosis, as well as weight control, andbone formation. Another important fatty acid with health-promoting anddisease-prevention properties is vaccenic acid (VA, t11-C18:1), a metabolic precursorof CLA. Although trans fatty acids naturally found in milk fat are associated withthese positive health benefits, trans fatty acids formed during the hydrogenationprocess for margarine production have been shown to have negative effects,increasing the risk of heart disease. Based on this understanding, this paper attemptsto establish a method to achieve the enrichment of VA and CLA for further functionalstudies.For the purpose of determination of vaccenic acid in milk and butter, a capillaryelectrophoresis method was established. The optimized conditions for buffer solutionwere4%(w/v) β-CD,54mmol·L-1SDS,80mmol·L-1borate (pH9.0),8mol·L-1ureaand4%(v/v) methanol. The separation voltage was set at25kV, and the columntemperature was set at15°C. The calibration curve was linear between the peak areaand the concentration in the range of100~2500μg·mL-1for vaccenic acid with thecorrelation coefficient was0.9817. The detection limit and the average recovery were10μg·mL-1and95.6%, respectively. The content of vaccenic acid was11.25mg·g-1fatty acids in milk and7.54mg·g-1fatty acids in butter，and the content of CLA was9.86mg·g-1fatty acids in milk and9.92mg·g-1fatty acids in butter as detected bycapillary electrophoresis. Besides, this method can detect the main conjugated linoleicacids in milk and butter at the same time.The preparation of high purity conjugated linoleic acid and vaccenic acid is thepremise of research and development. To obtain concentrated natural CLA and VAfrom milk fat by urea complexation, milk fat was hydrolyzed to provide free fatty acids, followed by crystallization with different ratios of urea. Study was made on themain conditions, such as urea adduction process, reflux time, inclusion time, inclusiontemperature, ratio of urea and solvent, affected the purity and yield of CLA and VA. Itshowed that the ratio of urea and solvent are the main factors that influence the purityand yield of CLA and VA. When mixed fatty acid, urea and ethanol for1:3:9(W/W/V)at room temperature, the condition of enrichment of CLA and VA reach the optimum.At this point, the purity of CLA is10.12%, the yield is75.03%, while the purity ofvaccenic acid is3.02%, and the yield is36.11%.