Preparation, Characterization Of Diacylglycerols And Application Research On Water-in-Oil Emulsions

The molecular structure of the diacylglycerols（DAG）gives its properties of emulsification,lubrication and safety,and also has the advantages of good nutrition and good workability.DAG can regulate blood lipid,lose weight,relieve diabetes,prevent arteriosclerosis,decrease the burden of the intestine etc..Therefore,it can be used as a functional oil substitute.Novozyme 435 lipase as catalyst,crude DAG were prepared via the enzymatic esterification（Novozyme 435）from caprilic/capric acid and glycerol followed by purified by molecular distillation at different temperatures（100℃,120℃and140℃）,then collected the components of light phase（fatty acid and monoglyceride）and heavy phase（diacylglycerols and triglycerides）.The molecular distillation products were purified by silica gel column chromatography to obtain the high purity DAG.The obtained the high purity DAGs were characterized by differential scanning calorimeter（DSC）,polarized light microscope（PLM）and so on.The results showed that the contents of C₈ DAG and C₁₀0 DAG in the crude products were 41.8±0.2%and44.5±0.1%,respectively.By comparison,the optimum temperature of separation was120℃,and the content of C₈ DAG and C₁₀0 DAG were 80.72±0.2%and 83.79±0.1%,respectively.The eluant of petroleum ether/ethyl acetate（volume rate of 4:1）has a best separation effect during the operation process of silica gel column chromatography,and both of two DAG content were up to 99%.The crystallization point and melting point of high purity C₈ DAG was less than high purity of C₁₀0 DAG and possibly showedβform crystal.The crystal particles of high purity C₈DAG are tiny and uniform whereas the high purity C₁₀0 DAG is larger flocculent crystal.Diacylglycerols（DAG）which abounds in medium chain diacylglycerols（MCD）and medium-and long-chain diacylglycerols（MLCD）were prepared via the enzymaticesterification（Novozyme435）frommoleculardistillated monoacylglycerols（MAG,53%palmitic acid MAG and 42%stearic acid MAG）and capric acid.The obtained DAG were characterized by DSC,PLM et al.The selected conditions were determined to be:the molar ratio of capric acid to MAG was 1:1,the enzyme loading amount was 5 wt.%,the reaction temperature was 65℃and the reaction time was 35 min.Under these conditions,the content of DAG was37.3±0.1%（consists of 7.28±0.1%of MCD and 30.02±0.1%of MLCD）with a mass ratio of DAG to TAG of 9.8:1 in the crude products.Solid fat content（SFC）profiles of the products demonstrated the potential value in plastic fats after purification.XRD reflected that the dominant crystal form in final system wasβformThe fat-crystallized W/O emulsions consisted of 20%water,80%canola oil,hydrogenated soybean oil（1%,3%,5%,7%,9%of the total mass oil phase）,high purity caprilic/capric DAG（5%of the total mass oil phase）.This experiment explored the performance and application of DAG in stabilizing emulsion.The result showed that high purity medium DAG can promote the interfacial crystallization of TAG（mainly composition of HSF）in the oil-water interface.Meanwhile,the addition of HSF in the emulsion system has a significant effect on the particle size distribution.