Studies On Prepration Of Human Milk Fat Substitutes And Quality Evaluation From Palm Stearin

This study focuses on the synthesis of human milk fat substitutes(HMFS)from the triglycerides rich in sn-2 palmitic acid obtained from palm stearin in different methods.Moreover,the reaction conditions were optimized by the univariate tests and response surface methodology(RSM).Finally,the quality of HMFS were evaluationed.The monoacylglycerol and diacylglycerol were not detected in raw palm stearin;the palm stearin was rich in C16:0(58.76%),C18:0(6.19%),C18:1(27.12%)and C18:2(5.37%).And,the composition of sn-2 fatty acid analysis showed that the main fatty acids were C16:0(37.25%)and C18:1(48.51%);the triglycerides were mainly composed of PPP(16.67%),POP(31.16%)and OPO(13.65%).Lipozyme TL IM and sodium methoxide were tested in the initial screening for the optimum catalyst of intramolecular rearrangement reaction.Compared with Lipozyme TL IM,the chemical catalyst sodium methoxide showed the higher activity and shorter reaction time.The sn-2 palmitic acid in palm stearin was enriched through the intramolecular rearrangement reactions catalyzed by sodium methoxide in solvent-free system.The optimum reaction conditions were investigated using RSM and the content of sn-2 palmitic acid was considered as objective functions.The experimental results showed that the optimum conditions of transesterification reaction were as follows,the temperature was 80 ?,reaction time was 33 min,and sodium methoxide dosage was 0.33%.Under this condition,the content of sn-2 palmitic acid was 60.71%,which can be satisfied as the intermediate for the preparation of HMFS.The HMFS was synthesized by the acidolysis of triglycerides containing sn-2 palmitic acid of 60.71% and oleic acid catalyzed by Lipozyme RM IM in solvent-free system.In addition,the optimum reaction conditions were investigated using RSM and the content of palmitic acid and sn-2 palmitic acid in products were considered as objective functions.Furthermore,the optimum conditions were the temperature was 69 ?,mass ratio of substrate was 1:3.17,enzyme dosage was 4.84%,water dosage was 8%,and the reaction time was 3.6 h.Besides,the content of palmitic acid and sn-2 palmitic acid were 27.23% and 50.45% under optimum conditions,respectively.What is more,the formulate optimization of mixed fatty acid(lauric acid,myristic acid,stearic acid,oleic acid,linoleic acid)were carried out under the optimum conditions.According to six model experiments,the fourth model was better of preparing HMFS.Correspondingly,the mass ratio was 1:0.75:0.75:10:1,the similarity of the fatty acid composition and position distribution of HMFS to the selecting human milk fat standard was the highest.Furthermore,molecular distillation was employed for the purification of HMFS.The acid value,peroxide value and solid fat content were low.But,the oxidation stability analysis of HMFS showed that the stability of products was decreased.